diff options
Diffstat (limited to 'kernel/trace/ring_buffer.c')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 2261 |
1 files changed, 1681 insertions, 580 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 2326b04c95c..ff7027199a9 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -3,24 +3,31 @@ * * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> */ +#include <linux/ftrace_event.h> #include <linux/ring_buffer.h> #include <linux/trace_clock.h> -#include <linux/ftrace_irq.h> +#include <linux/trace_seq.h> #include <linux/spinlock.h> +#include <linux/irq_work.h> #include <linux/debugfs.h> #include <linux/uaccess.h> #include <linux/hardirq.h> +#include <linux/kthread.h> /* for self test */ #include <linux/kmemcheck.h> #include <linux/module.h> #include <linux/percpu.h> #include <linux/mutex.h> +#include <linux/delay.h> +#include <linux/slab.h> #include <linux/init.h> #include <linux/hash.h> #include <linux/list.h> #include <linux/cpu.h> #include <linux/fs.h> -#include "trace.h" +#include <asm/local.h> + +static void update_pages_handler(struct work_struct *work); /* * The ring buffer header is special. We must manually up keep it. @@ -29,11 +36,11 @@ int ring_buffer_print_entry_header(struct trace_seq *s) { int ret; - ret = trace_seq_printf(s, "# compressed entry header\n"); - ret = trace_seq_printf(s, "\ttype_len : 5 bits\n"); - ret = trace_seq_printf(s, "\ttime_delta : 27 bits\n"); - ret = trace_seq_printf(s, "\tarray : 32 bits\n"); - ret = trace_seq_printf(s, "\n"); + ret = trace_seq_puts(s, "# compressed entry header\n"); + ret = trace_seq_puts(s, "\ttype_len : 5 bits\n"); + ret = trace_seq_puts(s, "\ttime_delta : 27 bits\n"); + ret = trace_seq_puts(s, "\tarray : 32 bits\n"); + ret = trace_seq_putc(s, '\n'); ret = trace_seq_printf(s, "\tpadding : type == %d\n", RINGBUF_TYPE_PADDING); ret = trace_seq_printf(s, "\ttime_extend : type == %d\n", @@ -153,33 +160,10 @@ enum { static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; -#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) +/* Used for individual buffers (after the counter) */ +#define RB_BUFFER_OFF (1 << 20) -/** - * tracing_on - enable all tracing buffers - * - * This function enables all tracing buffers that may have been - * disabled with tracing_off. - */ -void tracing_on(void) -{ - set_bit(RB_BUFFERS_ON_BIT, &ring_buffer_flags); -} -EXPORT_SYMBOL_GPL(tracing_on); - -/** - * tracing_off - turn off all tracing buffers - * - * This function stops all tracing buffers from recording data. - * It does not disable any overhead the tracers themselves may - * be causing. This function simply causes all recording to - * the ring buffers to fail. - */ -void tracing_off(void) -{ - clear_bit(RB_BUFFERS_ON_BIT, &ring_buffer_flags); -} -EXPORT_SYMBOL_GPL(tracing_off); +#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) /** * tracing_off_permanent - permanently disable ring buffers @@ -192,20 +176,21 @@ void tracing_off_permanent(void) set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags); } -/** - * tracing_is_on - show state of ring buffers enabled - */ -int tracing_is_on(void) -{ - return ring_buffer_flags == RB_BUFFERS_ON; -} -EXPORT_SYMBOL_GPL(tracing_is_on); - #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) #define RB_ALIGNMENT 4U #define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) #define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ +#ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS +# define RB_FORCE_8BYTE_ALIGNMENT 0 +# define RB_ARCH_ALIGNMENT RB_ALIGNMENT +#else +# define RB_FORCE_8BYTE_ALIGNMENT 1 +# define RB_ARCH_ALIGNMENT 8U +#endif + +#define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) + /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX @@ -214,6 +199,9 @@ enum { RB_LEN_TIME_STAMP = 16, }; +#define skip_time_extend(event) \ + ((struct ring_buffer_event *)((char *)event + RB_LEN_TIME_EXTEND)) + static inline int rb_null_event(struct ring_buffer_event *event) { return event->type_len == RINGBUF_TYPE_PADDING && !event->time_delta; @@ -238,8 +226,12 @@ rb_event_data_length(struct ring_buffer_event *event) return length + RB_EVNT_HDR_SIZE; } -/* inline for ring buffer fast paths */ -static unsigned +/* + * Return the length of the given event. Will return + * the length of the time extend if the event is a + * time extend. + */ +static inline unsigned rb_event_length(struct ring_buffer_event *event) { switch (event->type_len) { @@ -264,13 +256,41 @@ rb_event_length(struct ring_buffer_event *event) return 0; } +/* + * Return total length of time extend and data, + * or just the event length for all other events. + */ +static inline unsigned +rb_event_ts_length(struct ring_buffer_event *event) +{ + unsigned len = 0; + + if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { + /* time extends include the data event after it */ + len = RB_LEN_TIME_EXTEND; + event = skip_time_extend(event); + } + return len + rb_event_length(event); +} + /** * ring_buffer_event_length - return the length of the event * @event: the event to get the length of + * + * Returns the size of the data load of a data event. + * If the event is something other than a data event, it + * returns the size of the event itself. With the exception + * of a TIME EXTEND, where it still returns the size of the + * data load of the data event after it. */ unsigned ring_buffer_event_length(struct ring_buffer_event *event) { - unsigned length = rb_event_length(event); + unsigned length; + + if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) + event = skip_time_extend(event); + + length = rb_event_length(event); if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX) return length; length -= RB_EVNT_HDR_SIZE; @@ -284,6 +304,8 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_length); static void * rb_event_data(struct ring_buffer_event *event) { + if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) + event = skip_time_extend(event); BUG_ON(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX); /* If length is in len field, then array[0] has the data */ if (event->type_len) @@ -309,10 +331,15 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data); #define TS_MASK ((1ULL << TS_SHIFT) - 1) #define TS_DELTA_TEST (~TS_MASK) +/* Flag when events were overwritten */ +#define RB_MISSED_EVENTS (1 << 31) +/* Missed count stored at end */ +#define RB_MISSED_STORED (1 << 30) + struct buffer_data_page { u64 time_stamp; /* page time stamp */ local_t commit; /* write committed index */ - unsigned char data[]; /* data of buffer page */ + unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ }; /* @@ -328,6 +355,7 @@ struct buffer_page { local_t write; /* index for next write */ unsigned read; /* index for next read */ local_t entries; /* entries on this page */ + unsigned long real_end; /* real end of data */ struct buffer_data_page *page; /* Actual data page */ }; @@ -388,9 +416,6 @@ static inline int test_time_stamp(u64 delta) /* Max payload is BUF_PAGE_SIZE - header (8bytes) */ #define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2)) -/* Max number of timestamps that can fit on a page */ -#define RB_TIMESTAMPS_PER_PAGE (BUF_PAGE_SIZE / RB_LEN_TIME_STAMP) - int ring_buffer_print_page_header(struct trace_seq *s) { struct buffer_data_page field; @@ -407,6 +432,12 @@ int ring_buffer_print_page_header(struct trace_seq *s) (unsigned int)sizeof(field.commit), (unsigned int)is_signed_type(long)); + ret = trace_seq_printf(s, "\tfield: int overwrite;\t" + "offset:%u;\tsize:%u;\tsigned:%u;\n", + (unsigned int)offsetof(typeof(field), commit), + 1, + (unsigned int)is_signed_type(long)); + ret = trace_seq_printf(s, "\tfield: char data;\t" "offset:%u;\tsize:%u;\tsigned:%u;\n", (unsigned int)offsetof(typeof(field), data), @@ -416,36 +447,55 @@ int ring_buffer_print_page_header(struct trace_seq *s) return ret; } +struct rb_irq_work { + struct irq_work work; + wait_queue_head_t waiters; + bool waiters_pending; +}; + /* * head_page == tail_page && head == tail then buffer is empty. */ struct ring_buffer_per_cpu { int cpu; + atomic_t record_disabled; struct ring_buffer *buffer; - spinlock_t reader_lock; /* serialize readers */ + raw_spinlock_t reader_lock; /* serialize readers */ arch_spinlock_t lock; struct lock_class_key lock_key; + unsigned int nr_pages; struct list_head *pages; struct buffer_page *head_page; /* read from head */ struct buffer_page *tail_page; /* write to tail */ struct buffer_page *commit_page; /* committed pages */ struct buffer_page *reader_page; - local_t commit_overrun; - local_t overrun; + unsigned long lost_events; + unsigned long last_overrun; + local_t entries_bytes; local_t entries; + local_t overrun; + local_t commit_overrun; + local_t dropped_events; local_t committing; local_t commits; unsigned long read; + unsigned long read_bytes; u64 write_stamp; u64 read_stamp; - atomic_t record_disabled; + /* ring buffer pages to update, > 0 to add, < 0 to remove */ + int nr_pages_to_update; + struct list_head new_pages; /* new pages to add */ + struct work_struct update_pages_work; + struct completion update_done; + + struct rb_irq_work irq_work; }; struct ring_buffer { - unsigned pages; unsigned flags; int cpus; atomic_t record_disabled; + atomic_t resize_disabled; cpumask_var_t cpumask; struct lock_class_key *reader_lock_key; @@ -458,15 +508,133 @@ struct ring_buffer { struct notifier_block cpu_notify; #endif u64 (*clock)(void); + + struct rb_irq_work irq_work; }; struct ring_buffer_iter { struct ring_buffer_per_cpu *cpu_buffer; unsigned long head; struct buffer_page *head_page; + struct buffer_page *cache_reader_page; + unsigned long cache_read; u64 read_stamp; }; +/* + * rb_wake_up_waiters - wake up tasks waiting for ring buffer input + * + * Schedules a delayed work to wake up any task that is blocked on the + * ring buffer waiters queue. + */ +static void rb_wake_up_waiters(struct irq_work *work) +{ + struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work); + + wake_up_all(&rbwork->waiters); +} + +/** + * ring_buffer_wait - wait for input to the ring buffer + * @buffer: buffer to wait on + * @cpu: the cpu buffer to wait on + * + * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon + * as data is added to any of the @buffer's cpu buffers. Otherwise + * it will wait for data to be added to a specific cpu buffer. + */ +int ring_buffer_wait(struct ring_buffer *buffer, int cpu) +{ + struct ring_buffer_per_cpu *cpu_buffer; + DEFINE_WAIT(wait); + struct rb_irq_work *work; + + /* + * Depending on what the caller is waiting for, either any + * data in any cpu buffer, or a specific buffer, put the + * caller on the appropriate wait queue. + */ + if (cpu == RING_BUFFER_ALL_CPUS) + work = &buffer->irq_work; + else { + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return -ENODEV; + cpu_buffer = buffer->buffers[cpu]; + work = &cpu_buffer->irq_work; + } + + + prepare_to_wait(&work->waiters, &wait, TASK_INTERRUPTIBLE); + + /* + * The events can happen in critical sections where + * checking a work queue can cause deadlocks. + * After adding a task to the queue, this flag is set + * only to notify events to try to wake up the queue + * using irq_work. + * + * We don't clear it even if the buffer is no longer + * empty. The flag only causes the next event to run + * irq_work to do the work queue wake up. The worse + * that can happen if we race with !trace_empty() is that + * an event will cause an irq_work to try to wake up + * an empty queue. + * + * There's no reason to protect this flag either, as + * the work queue and irq_work logic will do the necessary + * synchronization for the wake ups. The only thing + * that is necessary is that the wake up happens after + * a task has been queued. It's OK for spurious wake ups. + */ + work->waiters_pending = true; + + if ((cpu == RING_BUFFER_ALL_CPUS && ring_buffer_empty(buffer)) || + (cpu != RING_BUFFER_ALL_CPUS && ring_buffer_empty_cpu(buffer, cpu))) + schedule(); + + finish_wait(&work->waiters, &wait); + return 0; +} + +/** + * ring_buffer_poll_wait - poll on buffer input + * @buffer: buffer to wait on + * @cpu: the cpu buffer to wait on + * @filp: the file descriptor + * @poll_table: The poll descriptor + * + * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon + * as data is added to any of the @buffer's cpu buffers. Otherwise + * it will wait for data to be added to a specific cpu buffer. + * + * Returns POLLIN | POLLRDNORM if data exists in the buffers, + * zero otherwise. + */ +int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu, + struct file *filp, poll_table *poll_table) +{ + struct ring_buffer_per_cpu *cpu_buffer; + struct rb_irq_work *work; + + if (cpu == RING_BUFFER_ALL_CPUS) + work = &buffer->irq_work; + else { + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return -EINVAL; + + cpu_buffer = buffer->buffers[cpu]; + work = &cpu_buffer->irq_work; + } + + work->waiters_pending = true; + poll_wait(filp, &work->waiters, poll_table); + + if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) || + (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu))) + return POLLIN | POLLRDNORM; + return 0; +} + /* buffer may be either ring_buffer or ring_buffer_per_cpu */ #define RB_WARN_ON(b, cond) \ ({ \ @@ -609,7 +777,7 @@ static struct list_head *rb_list_head(struct list_head *list) * the reader page). But if the next page is a header page, * its flags will be non zero. */ -static int inline +static inline int rb_is_head_page(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *page, struct list_head *list) { @@ -897,7 +1065,7 @@ static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer, } /** - * check_pages - integrity check of buffer pages + * rb_check_pages - integrity check of buffer pages * @cpu_buffer: CPU buffer with pages to test * * As a safety measure we check to make sure the data pages have not @@ -908,6 +1076,10 @@ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) struct list_head *head = cpu_buffer->pages; struct buffer_page *bpage, *tmp; + /* Reset the head page if it exists */ + if (cpu_buffer->head_page) + rb_set_head_page(cpu_buffer); + rb_head_page_deactivate(cpu_buffer); if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) @@ -934,33 +1106,55 @@ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) return 0; } -static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, - unsigned nr_pages) +static int __rb_allocate_pages(int nr_pages, struct list_head *pages, int cpu) { + int i; struct buffer_page *bpage, *tmp; - unsigned long addr; - LIST_HEAD(pages); - unsigned i; - - WARN_ON(!nr_pages); for (i = 0; i < nr_pages; i++) { + struct page *page; + /* + * __GFP_NORETRY flag makes sure that the allocation fails + * gracefully without invoking oom-killer and the system is + * not destabilized. + */ bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), - GFP_KERNEL, cpu_to_node(cpu_buffer->cpu)); + GFP_KERNEL | __GFP_NORETRY, + cpu_to_node(cpu)); if (!bpage) goto free_pages; - rb_check_bpage(cpu_buffer, bpage); - - list_add(&bpage->list, &pages); + list_add(&bpage->list, pages); - addr = __get_free_page(GFP_KERNEL); - if (!addr) + page = alloc_pages_node(cpu_to_node(cpu), + GFP_KERNEL | __GFP_NORETRY, 0); + if (!page) goto free_pages; - bpage->page = (void *)addr; + bpage->page = page_address(page); rb_init_page(bpage->page); } + return 0; + +free_pages: + list_for_each_entry_safe(bpage, tmp, pages, list) { + list_del_init(&bpage->list); + free_buffer_page(bpage); + } + + return -ENOMEM; +} + +static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, + unsigned nr_pages) +{ + LIST_HEAD(pages); + + WARN_ON(!nr_pages); + + if (__rb_allocate_pages(nr_pages, &pages, cpu_buffer->cpu)) + return -ENOMEM; + /* * The ring buffer page list is a circular list that does not * start and end with a list head. All page list items point to @@ -969,24 +1163,19 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, cpu_buffer->pages = pages.next; list_del(&pages); + cpu_buffer->nr_pages = nr_pages; + rb_check_pages(cpu_buffer); return 0; - - free_pages: - list_for_each_entry_safe(bpage, tmp, &pages, list) { - list_del_init(&bpage->list); - free_buffer_page(bpage); - } - return -ENOMEM; } static struct ring_buffer_per_cpu * -rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) +rb_allocate_cpu_buffer(struct ring_buffer *buffer, int nr_pages, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; struct buffer_page *bpage; - unsigned long addr; + struct page *page; int ret; cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), @@ -996,9 +1185,13 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) cpu_buffer->cpu = cpu; cpu_buffer->buffer = buffer; - spin_lock_init(&cpu_buffer->reader_lock); + raw_spin_lock_init(&cpu_buffer->reader_lock); lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key); cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; + INIT_WORK(&cpu_buffer->update_pages_work, update_pages_handler); + init_completion(&cpu_buffer->update_done); + init_irq_work(&cpu_buffer->irq_work.work, rb_wake_up_waiters); + init_waitqueue_head(&cpu_buffer->irq_work.waiters); bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), GFP_KERNEL, cpu_to_node(cpu)); @@ -1008,15 +1201,16 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) rb_check_bpage(cpu_buffer, bpage); cpu_buffer->reader_page = bpage; - addr = __get_free_page(GFP_KERNEL); - if (!addr) + page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, 0); + if (!page) goto fail_free_reader; - bpage->page = (void *)addr; + bpage->page = page_address(page); rb_init_page(bpage->page); INIT_LIST_HEAD(&cpu_buffer->reader_page->list); + INIT_LIST_HEAD(&cpu_buffer->new_pages); - ret = rb_allocate_pages(cpu_buffer, buffer->pages); + ret = rb_allocate_pages(cpu_buffer, nr_pages); if (ret < 0) goto fail_free_reader; @@ -1063,7 +1257,7 @@ static int rb_cpu_notify(struct notifier_block *self, #endif /** - * ring_buffer_alloc - allocate a new ring_buffer + * __ring_buffer_alloc - allocate a new ring_buffer * @size: the size in bytes per cpu that is needed. * @flags: attributes to set for the ring buffer. * @@ -1077,7 +1271,7 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, { struct ring_buffer *buffer; int bsize; - int cpu; + int cpu, nr_pages; /* keep it in its own cache line */ buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), @@ -1088,14 +1282,17 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) goto fail_free_buffer; - buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); + nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); buffer->flags = flags; buffer->clock = trace_clock_local; buffer->reader_lock_key = key; + init_irq_work(&buffer->irq_work.work, rb_wake_up_waiters); + init_waitqueue_head(&buffer->irq_work.waiters); + /* need at least two pages */ - if (buffer->pages < 2) - buffer->pages = 2; + if (nr_pages < 2) + nr_pages = 2; /* * In case of non-hotplug cpu, if the ring-buffer is allocated @@ -1103,7 +1300,7 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, * In that off case, we need to allocate for all possible cpus. */ #ifdef CONFIG_HOTPLUG_CPU - get_online_cpus(); + cpu_notifier_register_begin(); cpumask_copy(buffer->cpumask, cpu_online_mask); #else cpumask_copy(buffer->cpumask, cpu_possible_mask); @@ -1118,7 +1315,7 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, for_each_buffer_cpu(buffer, cpu) { buffer->buffers[cpu] = - rb_allocate_cpu_buffer(buffer, cpu); + rb_allocate_cpu_buffer(buffer, nr_pages, cpu); if (!buffer->buffers[cpu]) goto fail_free_buffers; } @@ -1126,10 +1323,10 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, #ifdef CONFIG_HOTPLUG_CPU buffer->cpu_notify.notifier_call = rb_cpu_notify; buffer->cpu_notify.priority = 0; - register_cpu_notifier(&buffer->cpu_notify); + __register_cpu_notifier(&buffer->cpu_notify); + cpu_notifier_register_done(); #endif - put_online_cpus(); mutex_init(&buffer->mutex); return buffer; @@ -1143,7 +1340,9 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, fail_free_cpumask: free_cpumask_var(buffer->cpumask); - put_online_cpus(); +#ifdef CONFIG_HOTPLUG_CPU + cpu_notifier_register_done(); +#endif fail_free_buffer: kfree(buffer); @@ -1160,16 +1359,17 @@ ring_buffer_free(struct ring_buffer *buffer) { int cpu; - get_online_cpus(); - #ifdef CONFIG_HOTPLUG_CPU - unregister_cpu_notifier(&buffer->cpu_notify); + cpu_notifier_register_begin(); + __unregister_cpu_notifier(&buffer->cpu_notify); #endif for_each_buffer_cpu(buffer, cpu) rb_free_cpu_buffer(buffer->buffers[cpu]); - put_online_cpus(); +#ifdef CONFIG_HOTPLUG_CPU + cpu_notifier_register_done(); +#endif kfree(buffer->buffers); free_cpumask_var(buffer->cpumask); @@ -1186,76 +1386,241 @@ void ring_buffer_set_clock(struct ring_buffer *buffer, static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); -static void -rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) +static inline unsigned long rb_page_entries(struct buffer_page *bpage) { - struct buffer_page *bpage; - struct list_head *p; - unsigned i; + return local_read(&bpage->entries) & RB_WRITE_MASK; +} - spin_lock_irq(&cpu_buffer->reader_lock); - rb_head_page_deactivate(cpu_buffer); +static inline unsigned long rb_page_write(struct buffer_page *bpage) +{ + return local_read(&bpage->write) & RB_WRITE_MASK; +} - for (i = 0; i < nr_pages; i++) { - if (RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages))) - return; - p = cpu_buffer->pages->next; - bpage = list_entry(p, struct buffer_page, list); - list_del_init(&bpage->list); - free_buffer_page(bpage); +static int +rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned int nr_pages) +{ + struct list_head *tail_page, *to_remove, *next_page; + struct buffer_page *to_remove_page, *tmp_iter_page; + struct buffer_page *last_page, *first_page; + unsigned int nr_removed; + unsigned long head_bit; + int page_entries; + + head_bit = 0; + + raw_spin_lock_irq(&cpu_buffer->reader_lock); + atomic_inc(&cpu_buffer->record_disabled); + /* + * We don't race with the readers since we have acquired the reader + * lock. We also don't race with writers after disabling recording. + * This makes it easy to figure out the first and the last page to be + * removed from the list. We unlink all the pages in between including + * the first and last pages. This is done in a busy loop so that we + * lose the least number of traces. + * The pages are freed after we restart recording and unlock readers. + */ + tail_page = &cpu_buffer->tail_page->list; + + /* + * tail page might be on reader page, we remove the next page + * from the ring buffer + */ + if (cpu_buffer->tail_page == cpu_buffer->reader_page) + tail_page = rb_list_head(tail_page->next); + to_remove = tail_page; + + /* start of pages to remove */ + first_page = list_entry(rb_list_head(to_remove->next), + struct buffer_page, list); + + for (nr_removed = 0; nr_removed < nr_pages; nr_removed++) { + to_remove = rb_list_head(to_remove)->next; + head_bit |= (unsigned long)to_remove & RB_PAGE_HEAD; } - if (RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages))) - return; - rb_reset_cpu(cpu_buffer); - rb_check_pages(cpu_buffer); + next_page = rb_list_head(to_remove)->next; + + /* + * Now we remove all pages between tail_page and next_page. + * Make sure that we have head_bit value preserved for the + * next page + */ + tail_page->next = (struct list_head *)((unsigned long)next_page | + head_bit); + next_page = rb_list_head(next_page); + next_page->prev = tail_page; + + /* make sure pages points to a valid page in the ring buffer */ + cpu_buffer->pages = next_page; + + /* update head page */ + if (head_bit) + cpu_buffer->head_page = list_entry(next_page, + struct buffer_page, list); + + /* + * change read pointer to make sure any read iterators reset + * themselves + */ + cpu_buffer->read = 0; + + /* pages are removed, resume tracing and then free the pages */ + atomic_dec(&cpu_buffer->record_disabled); + raw_spin_unlock_irq(&cpu_buffer->reader_lock); + + RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages)); + + /* last buffer page to remove */ + last_page = list_entry(rb_list_head(to_remove), struct buffer_page, + list); + tmp_iter_page = first_page; + + do { + to_remove_page = tmp_iter_page; + rb_inc_page(cpu_buffer, &tmp_iter_page); + + /* update the counters */ + page_entries = rb_page_entries(to_remove_page); + if (page_entries) { + /* + * If something was added to this page, it was full + * since it is not the tail page. So we deduct the + * bytes consumed in ring buffer from here. + * Increment overrun to account for the lost events. + */ + local_add(page_entries, &cpu_buffer->overrun); + local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); + } + + /* + * We have already removed references to this list item, just + * free up the buffer_page and its page + */ + free_buffer_page(to_remove_page); + nr_removed--; + + } while (to_remove_page != last_page); - spin_unlock_irq(&cpu_buffer->reader_lock); + RB_WARN_ON(cpu_buffer, nr_removed); + + return nr_removed == 0; } -static void -rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, - struct list_head *pages, unsigned nr_pages) +static int +rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer) { - struct buffer_page *bpage; - struct list_head *p; - unsigned i; + struct list_head *pages = &cpu_buffer->new_pages; + int retries, success; - spin_lock_irq(&cpu_buffer->reader_lock); - rb_head_page_deactivate(cpu_buffer); + raw_spin_lock_irq(&cpu_buffer->reader_lock); + /* + * We are holding the reader lock, so the reader page won't be swapped + * in the ring buffer. Now we are racing with the writer trying to + * move head page and the tail page. + * We are going to adapt the reader page update process where: + * 1. We first splice the start and end of list of new pages between + * the head page and its previous page. + * 2. We cmpxchg the prev_page->next to point from head page to the + * start of new pages list. + * 3. Finally, we update the head->prev to the end of new list. + * + * We will try this process 10 times, to make sure that we don't keep + * spinning. + */ + retries = 10; + success = 0; + while (retries--) { + struct list_head *head_page, *prev_page, *r; + struct list_head *last_page, *first_page; + struct list_head *head_page_with_bit; - for (i = 0; i < nr_pages; i++) { - if (RB_WARN_ON(cpu_buffer, list_empty(pages))) - return; - p = pages->next; - bpage = list_entry(p, struct buffer_page, list); - list_del_init(&bpage->list); - list_add_tail(&bpage->list, cpu_buffer->pages); + head_page = &rb_set_head_page(cpu_buffer)->list; + if (!head_page) + break; + prev_page = head_page->prev; + + first_page = pages->next; + last_page = pages->prev; + + head_page_with_bit = (struct list_head *) + ((unsigned long)head_page | RB_PAGE_HEAD); + + last_page->next = head_page_with_bit; + first_page->prev = prev_page; + + r = cmpxchg(&prev_page->next, head_page_with_bit, first_page); + + if (r == head_page_with_bit) { + /* + * yay, we replaced the page pointer to our new list, + * now, we just have to update to head page's prev + * pointer to point to end of list + */ + head_page->prev = last_page; + success = 1; + break; + } } - rb_reset_cpu(cpu_buffer); - rb_check_pages(cpu_buffer); - spin_unlock_irq(&cpu_buffer->reader_lock); + if (success) + INIT_LIST_HEAD(pages); + /* + * If we weren't successful in adding in new pages, warn and stop + * tracing + */ + RB_WARN_ON(cpu_buffer, !success); + raw_spin_unlock_irq(&cpu_buffer->reader_lock); + + /* free pages if they weren't inserted */ + if (!success) { + struct buffer_page *bpage, *tmp; + list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, + list) { + list_del_init(&bpage->list); + free_buffer_page(bpage); + } + } + return success; +} + +static void rb_update_pages(struct ring_buffer_per_cpu *cpu_buffer) +{ + int success; + + if (cpu_buffer->nr_pages_to_update > 0) + success = rb_insert_pages(cpu_buffer); + else + success = rb_remove_pages(cpu_buffer, + -cpu_buffer->nr_pages_to_update); + + if (success) + cpu_buffer->nr_pages += cpu_buffer->nr_pages_to_update; +} + +static void update_pages_handler(struct work_struct *work) +{ + struct ring_buffer_per_cpu *cpu_buffer = container_of(work, + struct ring_buffer_per_cpu, update_pages_work); + rb_update_pages(cpu_buffer); + complete(&cpu_buffer->update_done); } /** * ring_buffer_resize - resize the ring buffer * @buffer: the buffer to resize. * @size: the new size. + * @cpu_id: the cpu buffer to resize * * Minimum size is 2 * BUF_PAGE_SIZE. * - * Returns -1 on failure. + * Returns 0 on success and < 0 on failure. */ -int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) +int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, + int cpu_id) { struct ring_buffer_per_cpu *cpu_buffer; - unsigned nr_pages, rm_pages, new_pages; - struct buffer_page *bpage, *tmp; - unsigned long buffer_size; - unsigned long addr; - LIST_HEAD(pages); - int i, cpu; + unsigned nr_pages; + int cpu, err = 0; /* * Always succeed at resizing a non-existent buffer: @@ -1263,109 +1628,199 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) if (!buffer) return size; + /* Make sure the requested buffer exists */ + if (cpu_id != RING_BUFFER_ALL_CPUS && + !cpumask_test_cpu(cpu_id, buffer->cpumask)) + return size; + size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); size *= BUF_PAGE_SIZE; - buffer_size = buffer->pages * BUF_PAGE_SIZE; /* we need a minimum of two pages */ if (size < BUF_PAGE_SIZE * 2) size = BUF_PAGE_SIZE * 2; - if (size == buffer_size) - return size; - - atomic_inc(&buffer->record_disabled); + nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); - /* Make sure all writers are done with this buffer. */ - synchronize_sched(); + /* + * Don't succeed if resizing is disabled, as a reader might be + * manipulating the ring buffer and is expecting a sane state while + * this is true. + */ + if (atomic_read(&buffer->resize_disabled)) + return -EBUSY; + /* prevent another thread from changing buffer sizes */ mutex_lock(&buffer->mutex); - get_online_cpus(); - nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); - - if (size < buffer_size) { + if (cpu_id == RING_BUFFER_ALL_CPUS) { + /* calculate the pages to update */ + for_each_buffer_cpu(buffer, cpu) { + cpu_buffer = buffer->buffers[cpu]; - /* easy case, just free pages */ - if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) - goto out_fail; + cpu_buffer->nr_pages_to_update = nr_pages - + cpu_buffer->nr_pages; + /* + * nothing more to do for removing pages or no update + */ + if (cpu_buffer->nr_pages_to_update <= 0) + continue; + /* + * to add pages, make sure all new pages can be + * allocated without receiving ENOMEM + */ + INIT_LIST_HEAD(&cpu_buffer->new_pages); + if (__rb_allocate_pages(cpu_buffer->nr_pages_to_update, + &cpu_buffer->new_pages, cpu)) { + /* not enough memory for new pages */ + err = -ENOMEM; + goto out_err; + } + } - rm_pages = buffer->pages - nr_pages; + get_online_cpus(); + /* + * Fire off all the required work handlers + * We can't schedule on offline CPUs, but it's not necessary + * since we can change their buffer sizes without any race. + */ + for_each_buffer_cpu(buffer, cpu) { + cpu_buffer = buffer->buffers[cpu]; + if (!cpu_buffer->nr_pages_to_update) + continue; + + /* The update must run on the CPU that is being updated. */ + preempt_disable(); + if (cpu == smp_processor_id() || !cpu_online(cpu)) { + rb_update_pages(cpu_buffer); + cpu_buffer->nr_pages_to_update = 0; + } else { + /* + * Can not disable preemption for schedule_work_on() + * on PREEMPT_RT. + */ + preempt_enable(); + schedule_work_on(cpu, + &cpu_buffer->update_pages_work); + preempt_disable(); + } + preempt_enable(); + } + /* wait for all the updates to complete */ for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; - rb_remove_pages(cpu_buffer, rm_pages); + if (!cpu_buffer->nr_pages_to_update) + continue; + + if (cpu_online(cpu)) + wait_for_completion(&cpu_buffer->update_done); + cpu_buffer->nr_pages_to_update = 0; } - goto out; - } - /* - * This is a bit more difficult. We only want to add pages - * when we can allocate enough for all CPUs. We do this - * by allocating all the pages and storing them on a local - * link list. If we succeed in our allocation, then we - * add these pages to the cpu_buffers. Otherwise we just free - * them all and return -ENOMEM; - */ - if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) - goto out_fail; + put_online_cpus(); + } else { + /* Make sure this CPU has been intitialized */ + if (!cpumask_test_cpu(cpu_id, buffer->cpumask)) + goto out; - new_pages = nr_pages - buffer->pages; + cpu_buffer = buffer->buffers[cpu_id]; - for_each_buffer_cpu(buffer, cpu) { - for (i = 0; i < new_pages; i++) { - bpage = kzalloc_node(ALIGN(sizeof(*bpage), - cache_line_size()), - GFP_KERNEL, cpu_to_node(cpu)); - if (!bpage) - goto free_pages; - list_add(&bpage->list, &pages); - addr = __get_free_page(GFP_KERNEL); - if (!addr) - goto free_pages; - bpage->page = (void *)addr; - rb_init_page(bpage->page); + if (nr_pages == cpu_buffer->nr_pages) + goto out; + + cpu_buffer->nr_pages_to_update = nr_pages - + cpu_buffer->nr_pages; + + INIT_LIST_HEAD(&cpu_buffer->new_pages); + if (cpu_buffer->nr_pages_to_update > 0 && + __rb_allocate_pages(cpu_buffer->nr_pages_to_update, + &cpu_buffer->new_pages, cpu_id)) { + err = -ENOMEM; + goto out_err; } - } - for_each_buffer_cpu(buffer, cpu) { - cpu_buffer = buffer->buffers[cpu]; - rb_insert_pages(cpu_buffer, &pages, new_pages); - } + get_online_cpus(); - if (RB_WARN_ON(buffer, !list_empty(&pages))) - goto out_fail; + preempt_disable(); + /* The update must run on the CPU that is being updated. */ + if (cpu_id == smp_processor_id() || !cpu_online(cpu_id)) + rb_update_pages(cpu_buffer); + else { + /* + * Can not disable preemption for schedule_work_on() + * on PREEMPT_RT. + */ + preempt_enable(); + schedule_work_on(cpu_id, + &cpu_buffer->update_pages_work); + wait_for_completion(&cpu_buffer->update_done); + preempt_disable(); + } + preempt_enable(); + + cpu_buffer->nr_pages_to_update = 0; + put_online_cpus(); + } out: - buffer->pages = nr_pages; - put_online_cpus(); + /* + * The ring buffer resize can happen with the ring buffer + * enabled, so that the update disturbs the tracing as little + * as possible. But if the buffer is disabled, we do not need + * to worry about that, and we can take the time to verify + * that the buffer is not corrupt. + */ + if (atomic_read(&buffer->record_disabled)) { + atomic_inc(&buffer->record_disabled); + /* + * Even though the buffer was disabled, we must make sure + * that it is truly disabled before calling rb_check_pages. + * There could have been a race between checking + * record_disable and incrementing it. + */ + synchronize_sched(); + for_each_buffer_cpu(buffer, cpu) { + cpu_buffer = buffer->buffers[cpu]; + rb_check_pages(cpu_buffer); + } + atomic_dec(&buffer->record_disabled); + } + mutex_unlock(&buffer->mutex); + return size; - atomic_dec(&buffer->record_disabled); + out_err: + for_each_buffer_cpu(buffer, cpu) { + struct buffer_page *bpage, *tmp; - return size; + cpu_buffer = buffer->buffers[cpu]; + cpu_buffer->nr_pages_to_update = 0; - free_pages: - list_for_each_entry_safe(bpage, tmp, &pages, list) { - list_del_init(&bpage->list); - free_buffer_page(bpage); + if (list_empty(&cpu_buffer->new_pages)) + continue; + + list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, + list) { + list_del_init(&bpage->list); + free_buffer_page(bpage); + } } - put_online_cpus(); mutex_unlock(&buffer->mutex); - atomic_dec(&buffer->record_disabled); - return -ENOMEM; + return err; +} +EXPORT_SYMBOL_GPL(ring_buffer_resize); - /* - * Something went totally wrong, and we are too paranoid - * to even clean up the mess. - */ - out_fail: - put_online_cpus(); +void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val) +{ + mutex_lock(&buffer->mutex); + if (val) + buffer->flags |= RB_FL_OVERWRITE; + else + buffer->flags &= ~RB_FL_OVERWRITE; mutex_unlock(&buffer->mutex); - atomic_dec(&buffer->record_disabled); - return -1; } -EXPORT_SYMBOL_GPL(ring_buffer_resize); +EXPORT_SYMBOL_GPL(ring_buffer_change_overwrite); static inline void * __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) @@ -1391,22 +1846,12 @@ rb_iter_head_event(struct ring_buffer_iter *iter) return __rb_page_index(iter->head_page, iter->head); } -static inline unsigned long rb_page_write(struct buffer_page *bpage) -{ - return local_read(&bpage->write) & RB_WRITE_MASK; -} - static inline unsigned rb_page_commit(struct buffer_page *bpage) { return local_read(&bpage->page->commit); } -static inline unsigned long rb_page_entries(struct buffer_page *bpage) -{ - return local_read(&bpage->entries) & RB_WRITE_MASK; -} - -/* Size is determined by what has been commited */ +/* Size is determined by what has been committed */ static inline unsigned rb_page_size(struct buffer_page *bpage) { return rb_page_commit(bpage); @@ -1454,7 +1899,7 @@ rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) * assign the commit to the tail. */ again: - max_count = cpu_buffer->buffer->pages * 100; + max_count = cpu_buffer->nr_pages * 100; while (cpu_buffer->commit_page != cpu_buffer->tail_page) { if (RB_WARN_ON(cpu_buffer, !(--max_count))) @@ -1518,8 +1963,27 @@ static void rb_inc_iter(struct ring_buffer_iter *iter) iter->head = 0; } +/* Slow path, do not inline */ +static noinline struct ring_buffer_event * +rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) +{ + event->type_len = RINGBUF_TYPE_TIME_EXTEND; + + /* Not the first event on the page? */ + if (rb_event_index(event)) { + event->time_delta = delta & TS_MASK; + event->array[0] = delta >> TS_SHIFT; + } else { + /* nope, just zero it */ + event->time_delta = 0; + event->array[0] = 0; + } + + return skip_time_extend(event); +} + /** - * ring_buffer_update_event - update event type and data + * rb_update_event - update event type and data * @event: the even to update * @type: the type of event * @length: the size of the event field in the ring buffer @@ -1530,28 +1994,31 @@ static void rb_inc_iter(struct ring_buffer_iter *iter) * data field. */ static void -rb_update_event(struct ring_buffer_event *event, - unsigned type, unsigned length) +rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, + struct ring_buffer_event *event, unsigned length, + int add_timestamp, u64 delta) { - event->type_len = type; - - switch (type) { - - case RINGBUF_TYPE_PADDING: - case RINGBUF_TYPE_TIME_EXTEND: - case RINGBUF_TYPE_TIME_STAMP: - break; + /* Only a commit updates the timestamp */ + if (unlikely(!rb_event_is_commit(cpu_buffer, event))) + delta = 0; - case 0: - length -= RB_EVNT_HDR_SIZE; - if (length > RB_MAX_SMALL_DATA) - event->array[0] = length; - else - event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); - break; - default: - BUG(); + /* + * If we need to add a timestamp, then we + * add it to the start of the resevered space. + */ + if (unlikely(add_timestamp)) { + event = rb_add_time_stamp(event, delta); + length -= RB_LEN_TIME_EXTEND; + delta = 0; } + + event->time_delta = delta; + length -= RB_EVNT_HDR_SIZE; + if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { + event->type_len = 0; + event->array[0] = length; + } else + event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); } /* @@ -1600,6 +2067,7 @@ rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, * the counters. */ local_add(entries, &cpu_buffer->overrun); + local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); /* * The entries will be zeroed out when we move the @@ -1719,11 +2187,11 @@ static unsigned rb_calculate_event_length(unsigned length) if (!length) length = 1; - if (length > RB_MAX_SMALL_DATA) + if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) length += sizeof(event.array[0]); length += RB_EVNT_HDR_SIZE; - length = ALIGN(length, RB_ALIGNMENT); + length = ALIGN(length, RB_ARCH_ALIGNMENT); return length; } @@ -1740,6 +2208,14 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, * must fill the old tail_page with padding. */ if (tail >= BUF_PAGE_SIZE) { + /* + * If the page was filled, then we still need + * to update the real_end. Reset it to zero + * and the reader will ignore it. + */ + if (tail == BUF_PAGE_SIZE) + tail_page->real_end = 0; + local_sub(length, &tail_page->write); return; } @@ -1747,6 +2223,16 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, event = __rb_page_index(tail_page, tail); kmemcheck_annotate_bitfield(event, bitfield); + /* account for padding bytes */ + local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes); + + /* + * Save the original length to the meta data. + * This will be used by the reader to add lost event + * counter. + */ + tail_page->real_end = tail; + /* * If this event is bigger than the minimum size, then * we need to be careful that we don't subtract the @@ -1780,10 +2266,13 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, local_sub(length, &tail_page->write); } -static struct ring_buffer_event * +/* + * This is the slow path, force gcc not to inline it. + */ +static noinline struct ring_buffer_event * rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, unsigned long length, unsigned long tail, - struct buffer_page *tail_page, u64 *ts) + struct buffer_page *tail_page, u64 ts) { struct buffer_page *commit_page = cpu_buffer->commit_page; struct ring_buffer *buffer = cpu_buffer->buffer; @@ -1829,8 +2318,10 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, * If we are not in overwrite mode, * this is easy, just stop here. */ - if (!(buffer->flags & RB_FL_OVERWRITE)) + if (!(buffer->flags & RB_FL_OVERWRITE)) { + local_inc(&cpu_buffer->dropped_events); goto out_reset; + } ret = rb_handle_head_page(cpu_buffer, tail_page, @@ -1866,8 +2357,8 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, * Nested commits always have zero deltas, so * just reread the time stamp */ - *ts = rb_time_stamp(buffer); - next_page->page->time_stamp = *ts; + ts = rb_time_stamp(buffer); + next_page->page->time_stamp = ts; } out_again: @@ -1886,12 +2377,21 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, static struct ring_buffer_event * __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, - unsigned type, unsigned long length, u64 *ts) + unsigned long length, u64 ts, + u64 delta, int add_timestamp) { struct buffer_page *tail_page; struct ring_buffer_event *event; unsigned long tail, write; + /* + * If the time delta since the last event is too big to + * hold in the time field of the event, then we append a + * TIME EXTEND event ahead of the data event. + */ + if (unlikely(add_timestamp)) + length += RB_LEN_TIME_EXTEND; + tail_page = cpu_buffer->tail_page; write = local_add_return(length, &tail_page->write); @@ -1899,8 +2399,15 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, write &= RB_WRITE_MASK; tail = write - length; + /* + * If this is the first commit on the page, then it has the same + * timestamp as the page itself. + */ + if (!tail) + delta = 0; + /* See if we shot pass the end of this buffer page */ - if (write > BUF_PAGE_SIZE) + if (unlikely(write > BUF_PAGE_SIZE)) return rb_move_tail(cpu_buffer, length, tail, tail_page, ts); @@ -1908,18 +2415,19 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, event = __rb_page_index(tail_page, tail); kmemcheck_annotate_bitfield(event, bitfield); - rb_update_event(event, type, length); + rb_update_event(cpu_buffer, event, length, add_timestamp, delta); - /* The passed in type is zero for DATA */ - if (likely(!type)) - local_inc(&tail_page->entries); + local_inc(&tail_page->entries); /* * If this is the first commit on the page, then update * its timestamp. */ if (!tail) - tail_page->page->time_stamp = *ts; + tail_page->page->time_stamp = ts; + + /* account for these added bytes */ + local_add(length, &cpu_buffer->entries_bytes); return event; } @@ -1934,7 +2442,7 @@ rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, unsigned long addr; new_index = rb_event_index(event); - old_index = new_index + rb_event_length(event); + old_index = new_index + rb_event_ts_length(event); addr = (unsigned long)event; addr &= PAGE_MASK; @@ -1943,6 +2451,7 @@ rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) { unsigned long write_mask = local_read(&bpage->write) & ~RB_WRITE_MASK; + unsigned long event_length = rb_event_length(event); /* * This is on the tail page. It is possible that * a write could come in and move the tail page @@ -1952,88 +2461,24 @@ rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, old_index += write_mask; new_index += write_mask; index = local_cmpxchg(&bpage->write, old_index, new_index); - if (index == old_index) + if (index == old_index) { + /* update counters */ + local_sub(event_length, &cpu_buffer->entries_bytes); return 1; + } } /* could not discard */ return 0; } -static int -rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, - u64 *ts, u64 *delta) -{ - struct ring_buffer_event *event; - static int once; - int ret; - - if (unlikely(*delta > (1ULL << 59) && !once++)) { - printk(KERN_WARNING "Delta way too big! %llu" - " ts=%llu write stamp = %llu\n", - (unsigned long long)*delta, - (unsigned long long)*ts, - (unsigned long long)cpu_buffer->write_stamp); - WARN_ON(1); - } - - /* - * The delta is too big, we to add a - * new timestamp. - */ - event = __rb_reserve_next(cpu_buffer, - RINGBUF_TYPE_TIME_EXTEND, - RB_LEN_TIME_EXTEND, - ts); - if (!event) - return -EBUSY; - - if (PTR_ERR(event) == -EAGAIN) - return -EAGAIN; - - /* Only a commited time event can update the write stamp */ - if (rb_event_is_commit(cpu_buffer, event)) { - /* - * If this is the first on the page, then it was - * updated with the page itself. Try to discard it - * and if we can't just make it zero. - */ - if (rb_event_index(event)) { - event->time_delta = *delta & TS_MASK; - event->array[0] = *delta >> TS_SHIFT; - } else { - /* try to discard, since we do not need this */ - if (!rb_try_to_discard(cpu_buffer, event)) { - /* nope, just zero it */ - event->time_delta = 0; - event->array[0] = 0; - } - } - cpu_buffer->write_stamp = *ts; - /* let the caller know this was the commit */ - ret = 1; - } else { - /* Try to discard the event */ - if (!rb_try_to_discard(cpu_buffer, event)) { - /* Darn, this is just wasted space */ - event->time_delta = 0; - event->array[0] = 0; - } - ret = 0; - } - - *delta = 0; - - return ret; -} - static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer) { local_inc(&cpu_buffer->committing); local_inc(&cpu_buffer->commits); } -static void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) +static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) { unsigned long commits; @@ -2071,9 +2516,10 @@ rb_reserve_next_event(struct ring_buffer *buffer, unsigned long length) { struct ring_buffer_event *event; - u64 ts, delta = 0; - int commit = 0; + u64 ts, delta; int nr_loops = 0; + int add_timestamp; + u64 diff; rb_start_commit(cpu_buffer); @@ -2094,6 +2540,9 @@ rb_reserve_next_event(struct ring_buffer *buffer, length = rb_calculate_event_length(length); again: + add_timestamp = 0; + delta = 0; + /* * We allow for interrupts to reenter here and do a trace. * If one does, it will cause this original code to loop @@ -2107,56 +2556,40 @@ rb_reserve_next_event(struct ring_buffer *buffer, goto out_fail; ts = rb_time_stamp(cpu_buffer->buffer); + diff = ts - cpu_buffer->write_stamp; - /* - * Only the first commit can update the timestamp. - * Yes there is a race here. If an interrupt comes in - * just after the conditional and it traces too, then it - * will also check the deltas. More than one timestamp may - * also be made. But only the entry that did the actual - * commit will be something other than zero. - */ - if (likely(cpu_buffer->tail_page == cpu_buffer->commit_page && - rb_page_write(cpu_buffer->tail_page) == - rb_commit_index(cpu_buffer))) { - u64 diff; - - diff = ts - cpu_buffer->write_stamp; - - /* make sure this diff is calculated here */ - barrier(); - - /* Did the write stamp get updated already? */ - if (unlikely(ts < cpu_buffer->write_stamp)) - goto get_event; + /* make sure this diff is calculated here */ + barrier(); + /* Did the write stamp get updated already? */ + if (likely(ts >= cpu_buffer->write_stamp)) { delta = diff; if (unlikely(test_time_stamp(delta))) { - - commit = rb_add_time_stamp(cpu_buffer, &ts, &delta); - if (commit == -EBUSY) - goto out_fail; - - if (commit == -EAGAIN) - goto again; - - RB_WARN_ON(cpu_buffer, commit < 0); + int local_clock_stable = 1; +#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK + local_clock_stable = sched_clock_stable(); +#endif + WARN_ONCE(delta > (1ULL << 59), + KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", + (unsigned long long)delta, + (unsigned long long)ts, + (unsigned long long)cpu_buffer->write_stamp, + local_clock_stable ? "" : + "If you just came from a suspend/resume,\n" + "please switch to the trace global clock:\n" + " echo global > /sys/kernel/debug/tracing/trace_clock\n"); + add_timestamp = 1; } } - get_event: - event = __rb_reserve_next(cpu_buffer, 0, length, &ts); + event = __rb_reserve_next(cpu_buffer, length, ts, + delta, add_timestamp); if (unlikely(PTR_ERR(event) == -EAGAIN)) goto again; if (!event) goto out_fail; - if (!rb_event_is_commit(cpu_buffer, event)) - delta = 0; - - event->time_delta = delta; - return event; out_fail: @@ -2166,34 +2599,76 @@ rb_reserve_next_event(struct ring_buffer *buffer, #ifdef CONFIG_TRACING -#define TRACE_RECURSIVE_DEPTH 16 +/* + * The lock and unlock are done within a preempt disable section. + * The current_context per_cpu variable can only be modified + * by the current task between lock and unlock. But it can + * be modified more than once via an interrupt. To pass this + * information from the lock to the unlock without having to + * access the 'in_interrupt()' functions again (which do show + * a bit of overhead in something as critical as function tracing, + * we use a bitmask trick. + * + * bit 0 = NMI context + * bit 1 = IRQ context + * bit 2 = SoftIRQ context + * bit 3 = normal context. + * + * This works because this is the order of contexts that can + * preempt other contexts. A SoftIRQ never preempts an IRQ + * context. + * + * When the context is determined, the corresponding bit is + * checked and set (if it was set, then a recursion of that context + * happened). + * + * On unlock, we need to clear this bit. To do so, just subtract + * 1 from the current_context and AND it to itself. + * + * (binary) + * 101 - 1 = 100 + * 101 & 100 = 100 (clearing bit zero) + * + * 1010 - 1 = 1001 + * 1010 & 1001 = 1000 (clearing bit 1) + * + * The least significant bit can be cleared this way, and it + * just so happens that it is the same bit corresponding to + * the current context. + */ +static DEFINE_PER_CPU(unsigned int, current_context); -static int trace_recursive_lock(void) +static __always_inline int trace_recursive_lock(void) { - current->trace_recursion++; - - if (likely(current->trace_recursion < TRACE_RECURSIVE_DEPTH)) - return 0; + unsigned int val = this_cpu_read(current_context); + int bit; + + if (in_interrupt()) { + if (in_nmi()) + bit = 0; + else if (in_irq()) + bit = 1; + else + bit = 2; + } else + bit = 3; - /* Disable all tracing before we do anything else */ - tracing_off_permanent(); + if (unlikely(val & (1 << bit))) + return 1; - printk_once(KERN_WARNING "Tracing recursion: depth[%ld]:" - "HC[%lu]:SC[%lu]:NMI[%lu]\n", - current->trace_recursion, - hardirq_count() >> HARDIRQ_SHIFT, - softirq_count() >> SOFTIRQ_SHIFT, - in_nmi()); + val |= (1 << bit); + this_cpu_write(current_context, val); - WARN_ON_ONCE(1); - return -1; + return 0; } -static void trace_recursive_unlock(void) +static __always_inline void trace_recursive_unlock(void) { - WARN_ON_ONCE(!current->trace_recursion); + unsigned int val = this_cpu_read(current_context); - current->trace_recursion--; + val--; + val &= this_cpu_read(current_context); + this_cpu_write(current_context, val); } #else @@ -2203,8 +2678,6 @@ static void trace_recursive_unlock(void) #endif -static DEFINE_PER_CPU(int, rb_need_resched); - /** * ring_buffer_lock_reserve - reserve a part of the buffer * @buffer: the ring buffer to reserve from @@ -2225,16 +2698,16 @@ ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_event *event; - int cpu, resched; + int cpu; if (ring_buffer_flags != RB_BUFFERS_ON) return NULL; - if (atomic_read(&buffer->record_disabled)) - return NULL; - /* If we are tracing schedule, we don't want to recurse */ - resched = ftrace_preempt_disable(); + preempt_disable_notrace(); + + if (atomic_read(&buffer->record_disabled)) + goto out_nocheck; if (trace_recursive_lock()) goto out_nocheck; @@ -2256,21 +2729,13 @@ ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) if (!event) goto out; - /* - * Need to store resched state on this cpu. - * Only the first needs to. - */ - - if (preempt_count() == 1) - per_cpu(rb_need_resched, cpu) = resched; - return event; out: trace_recursive_unlock(); out_nocheck: - ftrace_preempt_enable(resched); + preempt_enable_notrace(); return NULL; } EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); @@ -2279,12 +2744,28 @@ static void rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) { + u64 delta; + /* * The event first in the commit queue updates the * time stamp. */ - if (rb_event_is_commit(cpu_buffer, event)) - cpu_buffer->write_stamp += event->time_delta; + if (rb_event_is_commit(cpu_buffer, event)) { + /* + * A commit event that is first on a page + * updates the write timestamp with the page stamp + */ + if (!rb_event_index(event)) + cpu_buffer->write_stamp = + cpu_buffer->commit_page->page->time_stamp; + else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { + delta = event->array[0]; + delta <<= TS_SHIFT; + delta += event->time_delta; + cpu_buffer->write_stamp += delta; + } else + cpu_buffer->write_stamp += event->time_delta; + } } static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, @@ -2295,6 +2776,22 @@ static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, rb_end_commit(cpu_buffer); } +static __always_inline void +rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) +{ + if (buffer->irq_work.waiters_pending) { + buffer->irq_work.waiters_pending = false; + /* irq_work_queue() supplies it's own memory barriers */ + irq_work_queue(&buffer->irq_work.work); + } + + if (cpu_buffer->irq_work.waiters_pending) { + cpu_buffer->irq_work.waiters_pending = false; + /* irq_work_queue() supplies it's own memory barriers */ + irq_work_queue(&cpu_buffer->irq_work.work); + } +} + /** * ring_buffer_unlock_commit - commit a reserved * @buffer: The buffer to commit to @@ -2314,15 +2811,11 @@ int ring_buffer_unlock_commit(struct ring_buffer *buffer, rb_commit(cpu_buffer, event); + rb_wakeups(buffer, cpu_buffer); + trace_recursive_unlock(); - /* - * Only the last preempt count needs to restore preemption. - */ - if (preempt_count() == 1) - ftrace_preempt_enable(per_cpu(rb_need_resched, cpu)); - else - preempt_enable_no_resched_notrace(); + preempt_enable_notrace(); return 0; } @@ -2330,6 +2823,9 @@ EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); static inline void rb_event_discard(struct ring_buffer_event *event) { + if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) + event = skip_time_extend(event); + /* array[0] holds the actual length for the discarded event */ event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; event->type_len = RINGBUF_TYPE_PADDING; @@ -2430,13 +2926,7 @@ void ring_buffer_discard_commit(struct ring_buffer *buffer, trace_recursive_unlock(); - /* - * Only the last preempt count needs to restore preemption. - */ - if (preempt_count() == 1) - ftrace_preempt_enable(per_cpu(rb_need_resched, cpu)); - else - preempt_enable_no_resched_notrace(); + preempt_enable_notrace(); } EXPORT_SYMBOL_GPL(ring_buffer_discard_commit); @@ -2455,22 +2945,22 @@ EXPORT_SYMBOL_GPL(ring_buffer_discard_commit); * and not the length of the event which would hold the header. */ int ring_buffer_write(struct ring_buffer *buffer, - unsigned long length, - void *data) + unsigned long length, + void *data) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_event *event; void *body; int ret = -EBUSY; - int cpu, resched; + int cpu; if (ring_buffer_flags != RB_BUFFERS_ON) return -EBUSY; - if (atomic_read(&buffer->record_disabled)) - return -EBUSY; + preempt_disable_notrace(); - resched = ftrace_preempt_disable(); + if (atomic_read(&buffer->record_disabled)) + goto out; cpu = raw_smp_processor_id(); @@ -2495,9 +2985,11 @@ int ring_buffer_write(struct ring_buffer *buffer, rb_commit(cpu_buffer, event); + rb_wakeups(buffer, cpu_buffer); + ret = 0; out: - ftrace_preempt_enable(resched); + preempt_enable_notrace(); return ret; } @@ -2539,7 +3031,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_disable); * @buffer: The ring buffer to enable writes * * Note, multiple disables will need the same number of enables - * to truely enable the writing (much like preempt_disable). + * to truly enable the writing (much like preempt_disable). */ void ring_buffer_record_enable(struct ring_buffer *buffer) { @@ -2548,6 +3040,63 @@ void ring_buffer_record_enable(struct ring_buffer *buffer) EXPORT_SYMBOL_GPL(ring_buffer_record_enable); /** + * ring_buffer_record_off - stop all writes into the buffer + * @buffer: The ring buffer to stop writes to. + * + * This prevents all writes to the buffer. Any attempt to write + * to the buffer after this will fail and return NULL. + * + * This is different than ring_buffer_record_disable() as + * it works like an on/off switch, where as the disable() version + * must be paired with a enable(). + */ +void ring_buffer_record_off(struct ring_buffer *buffer) +{ + unsigned int rd; + unsigned int new_rd; + + do { + rd = atomic_read(&buffer->record_disabled); + new_rd = rd | RB_BUFFER_OFF; + } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); +} +EXPORT_SYMBOL_GPL(ring_buffer_record_off); + +/** + * ring_buffer_record_on - restart writes into the buffer + * @buffer: The ring buffer to start writes to. + * + * This enables all writes to the buffer that was disabled by + * ring_buffer_record_off(). + * + * This is different than ring_buffer_record_enable() as + * it works like an on/off switch, where as the enable() version + * must be paired with a disable(). + */ +void ring_buffer_record_on(struct ring_buffer *buffer) +{ + unsigned int rd; + unsigned int new_rd; + + do { + rd = atomic_read(&buffer->record_disabled); + new_rd = rd & ~RB_BUFFER_OFF; + } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); +} +EXPORT_SYMBOL_GPL(ring_buffer_record_on); + +/** + * ring_buffer_record_is_on - return true if the ring buffer can write + * @buffer: The ring buffer to see if write is enabled + * + * Returns true if the ring buffer is in a state that it accepts writes. + */ +int ring_buffer_record_is_on(struct ring_buffer *buffer) +{ + return !atomic_read(&buffer->record_disabled); +} + +/** * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer * @buffer: The ring buffer to stop writes to. * @cpu: The CPU buffer to stop @@ -2575,7 +3124,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); * @cpu: The CPU to enable. * * Note, multiple disables will need the same number of enables - * to truely enable the writing (much like preempt_disable). + * to truly enable the writing (much like preempt_disable). */ void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) { @@ -2589,6 +3138,72 @@ void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) } EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); +/* + * The total entries in the ring buffer is the running counter + * of entries entered into the ring buffer, minus the sum of + * the entries read from the ring buffer and the number of + * entries that were overwritten. + */ +static inline unsigned long +rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) +{ + return local_read(&cpu_buffer->entries) - + (local_read(&cpu_buffer->overrun) + cpu_buffer->read); +} + +/** + * ring_buffer_oldest_event_ts - get the oldest event timestamp from the buffer + * @buffer: The ring buffer + * @cpu: The per CPU buffer to read from. + */ +u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu) +{ + unsigned long flags; + struct ring_buffer_per_cpu *cpu_buffer; + struct buffer_page *bpage; + u64 ret = 0; + + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return 0; + + cpu_buffer = buffer->buffers[cpu]; + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + /* + * if the tail is on reader_page, oldest time stamp is on the reader + * page + */ + if (cpu_buffer->tail_page == cpu_buffer->reader_page) + bpage = cpu_buffer->reader_page; + else + bpage = rb_set_head_page(cpu_buffer); + if (bpage) + ret = bpage->page->time_stamp; + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + + return ret; +} +EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts); + +/** + * ring_buffer_bytes_cpu - get the number of bytes consumed in a cpu buffer + * @buffer: The ring buffer + * @cpu: The per CPU buffer to read from. + */ +unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu) +{ + struct ring_buffer_per_cpu *cpu_buffer; + unsigned long ret; + + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return 0; + + cpu_buffer = buffer->buffers[cpu]; + ret = local_read(&cpu_buffer->entries_bytes) - cpu_buffer->read_bytes; + + return ret; +} +EXPORT_SYMBOL_GPL(ring_buffer_bytes_cpu); + /** * ring_buffer_entries_cpu - get the number of entries in a cpu buffer * @buffer: The ring buffer @@ -2597,21 +3212,19 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; - unsigned long ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 0; cpu_buffer = buffer->buffers[cpu]; - ret = (local_read(&cpu_buffer->entries) - local_read(&cpu_buffer->overrun)) - - cpu_buffer->read; - return ret; + return rb_num_of_entries(cpu_buffer); } EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); /** - * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer + * ring_buffer_overrun_cpu - get the number of overruns caused by the ring + * buffer wrapping around (only if RB_FL_OVERWRITE is on). * @buffer: The ring buffer * @cpu: The per CPU buffer to get the number of overruns from */ @@ -2631,7 +3244,9 @@ unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); /** - * ring_buffer_commit_overrun_cpu - get the number of overruns caused by commits + * ring_buffer_commit_overrun_cpu - get the number of overruns caused by + * commits failing due to the buffer wrapping around while there are uncommitted + * events, such as during an interrupt storm. * @buffer: The ring buffer * @cpu: The per CPU buffer to get the number of overruns from */ @@ -2652,6 +3267,46 @@ ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu) EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu); /** + * ring_buffer_dropped_events_cpu - get the number of dropped events caused by + * the ring buffer filling up (only if RB_FL_OVERWRITE is off). + * @buffer: The ring buffer + * @cpu: The per CPU buffer to get the number of overruns from + */ +unsigned long +ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu) +{ + struct ring_buffer_per_cpu *cpu_buffer; + unsigned long ret; + + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return 0; + + cpu_buffer = buffer->buffers[cpu]; + ret = local_read(&cpu_buffer->dropped_events); + + return ret; +} +EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu); + +/** + * ring_buffer_read_events_cpu - get the number of events successfully read + * @buffer: The ring buffer + * @cpu: The per CPU buffer to get the number of events read + */ +unsigned long +ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu) +{ + struct ring_buffer_per_cpu *cpu_buffer; + + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return 0; + + cpu_buffer = buffer->buffers[cpu]; + return cpu_buffer->read; +} +EXPORT_SYMBOL_GPL(ring_buffer_read_events_cpu); + +/** * ring_buffer_entries - get the number of entries in a buffer * @buffer: The ring buffer * @@ -2667,8 +3322,7 @@ unsigned long ring_buffer_entries(struct ring_buffer *buffer) /* if you care about this being correct, lock the buffer */ for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; - entries += (local_read(&cpu_buffer->entries) - - local_read(&cpu_buffer->overrun)) - cpu_buffer->read; + entries += rb_num_of_entries(cpu_buffer); } return entries; @@ -2716,6 +3370,8 @@ static void rb_iter_reset(struct ring_buffer_iter *iter) iter->read_stamp = cpu_buffer->read_stamp; else iter->read_stamp = iter->head_page->page->time_stamp; + iter->cache_reader_page = cpu_buffer->reader_page; + iter->cache_read = cpu_buffer->read; } /** @@ -2735,9 +3391,9 @@ void ring_buffer_iter_reset(struct ring_buffer_iter *iter) cpu_buffer = iter->cpu_buffer; - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_iter_reset(iter); - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); @@ -2822,6 +3478,7 @@ static struct buffer_page * rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) { struct buffer_page *reader = NULL; + unsigned long overwrite; unsigned long flags; int nr_loops = 0; int ret; @@ -2857,25 +3514,32 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) if (cpu_buffer->commit_page == cpu_buffer->reader_page) goto out; + /* Don't bother swapping if the ring buffer is empty */ + if (rb_num_of_entries(cpu_buffer) == 0) + goto out; + /* * Reset the reader page to size zero. */ local_set(&cpu_buffer->reader_page->write, 0); local_set(&cpu_buffer->reader_page->entries, 0); local_set(&cpu_buffer->reader_page->page->commit, 0); + cpu_buffer->reader_page->real_end = 0; spin: /* * Splice the empty reader page into the list around the head. */ reader = rb_set_head_page(cpu_buffer); - cpu_buffer->reader_page->list.next = reader->list.next; + if (!reader) + goto out; + cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); cpu_buffer->reader_page->list.prev = reader->list.prev; /* * cpu_buffer->pages just needs to point to the buffer, it * has no specific buffer page to point to. Lets move it out - * of our way so we don't accidently swap it. + * of our way so we don't accidentally swap it. */ cpu_buffer->pages = reader->list.prev; @@ -2883,6 +3547,18 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) rb_set_list_to_head(cpu_buffer, &cpu_buffer->reader_page->list); /* + * We want to make sure we read the overruns after we set up our + * pointers to the next object. The writer side does a + * cmpxchg to cross pages which acts as the mb on the writer + * side. Note, the reader will constantly fail the swap + * while the writer is updating the pointers, so this + * guarantees that the overwrite recorded here is the one we + * want to compare with the last_overrun. + */ + smp_mb(); + overwrite = local_read(&(cpu_buffer->overrun)); + + /* * Here's the tricky part. * * We need to move the pointer past the header page. @@ -2906,13 +3582,18 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) * * Now make the new head point back to the reader page. */ - reader->list.next->prev = &cpu_buffer->reader_page->list; + rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list; rb_inc_page(cpu_buffer, &cpu_buffer->head_page); /* Finally update the reader page to the new head */ cpu_buffer->reader_page = reader; rb_reset_reader_page(cpu_buffer); + if (overwrite != cpu_buffer->last_overrun) { + cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun; + cpu_buffer->last_overrun = overwrite; + } + goto again; out: @@ -2947,13 +3628,11 @@ static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) static void rb_advance_iter(struct ring_buffer_iter *iter) { - struct ring_buffer *buffer; struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_event *event; unsigned length; cpu_buffer = iter->cpu_buffer; - buffer = cpu_buffer->buffer; /* * Check if we are at the end of the buffer. @@ -2986,11 +3665,17 @@ static void rb_advance_iter(struct ring_buffer_iter *iter) /* check for end of page padding */ if ((iter->head >= rb_page_size(iter->head_page)) && (iter->head_page != cpu_buffer->commit_page)) - rb_advance_iter(iter); + rb_inc_iter(iter); +} + +static int rb_lost_events(struct ring_buffer_per_cpu *cpu_buffer) +{ + return cpu_buffer->lost_events; } static struct ring_buffer_event * -rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts) +rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, + unsigned long *lost_events) { struct ring_buffer_event *event; struct buffer_page *reader; @@ -2998,12 +3683,12 @@ rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts) again: /* - * We repeat when a timestamp is encountered. It is possible - * to get multiple timestamps from an interrupt entering just - * as one timestamp is about to be written, or from discarded - * commits. The most that we can have is the number on a single page. + * We repeat when a time extend is encountered. + * Since the time extend is always attached to a data event, + * we should never loop more than once. + * (We never hit the following condition more than twice). */ - if (RB_WARN_ON(cpu_buffer, ++nr_loops > RB_TIMESTAMPS_PER_PAGE)) + if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) return NULL; reader = rb_get_reader_page(cpu_buffer); @@ -3042,6 +3727,8 @@ rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts) ring_buffer_normalize_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu, ts); } + if (lost_events) + *lost_events = rb_lost_events(cpu_buffer); return event; default: @@ -3060,27 +3747,39 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) struct ring_buffer_event *event; int nr_loops = 0; - if (ring_buffer_iter_empty(iter)) - return NULL; - cpu_buffer = iter->cpu_buffer; buffer = cpu_buffer->buffer; + /* + * Check if someone performed a consuming read to + * the buffer. A consuming read invalidates the iterator + * and we need to reset the iterator in this case. + */ + if (unlikely(iter->cache_read != cpu_buffer->read || + iter->cache_reader_page != cpu_buffer->reader_page)) + rb_iter_reset(iter); + again: + if (ring_buffer_iter_empty(iter)) + return NULL; + /* - * We repeat when a timestamp is encountered. - * We can get multiple timestamps by nested interrupts or also - * if filtering is on (discarding commits). Since discarding - * commits can be frequent we can get a lot of timestamps. - * But we limit them by not adding timestamps if they begin - * at the start of a page. + * We repeat when a time extend is encountered. + * Since the time extend is always attached to a data event, + * we should never loop more than once. + * (We never hit the following condition more than twice). */ - if (RB_WARN_ON(cpu_buffer, ++nr_loops > RB_TIMESTAMPS_PER_PAGE)) + if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) return NULL; if (rb_per_cpu_empty(cpu_buffer)) return NULL; + if (iter->head >= local_read(&iter->head_page->page->commit)) { + rb_inc_iter(iter); + goto again; + } + event = rb_iter_head_event(iter); switch (event->type_len) { @@ -3138,12 +3837,14 @@ static inline int rb_ok_to_lock(void) * @buffer: The ring buffer to read * @cpu: The cpu to peak at * @ts: The timestamp counter of this event. + * @lost_events: a variable to store if events were lost (may be NULL) * * This will return the event that will be read next, but does * not consume the data. */ struct ring_buffer_event * -ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) +ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts, + unsigned long *lost_events) { struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; struct ring_buffer_event *event; @@ -3157,12 +3858,12 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) again: local_irq_save(flags); if (dolock) - spin_lock(&cpu_buffer->reader_lock); - event = rb_buffer_peek(cpu_buffer, ts); + raw_spin_lock(&cpu_buffer->reader_lock); + event = rb_buffer_peek(cpu_buffer, ts, lost_events); if (event && event->type_len == RINGBUF_TYPE_PADDING) rb_advance_reader(cpu_buffer); if (dolock) - spin_unlock(&cpu_buffer->reader_lock); + raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); if (event && event->type_len == RINGBUF_TYPE_PADDING) @@ -3187,9 +3888,9 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) unsigned long flags; again: - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); event = rb_iter_peek(iter, ts); - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); if (event && event->type_len == RINGBUF_TYPE_PADDING) goto again; @@ -3200,13 +3901,17 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) /** * ring_buffer_consume - return an event and consume it * @buffer: The ring buffer to get the next event from + * @cpu: the cpu to read the buffer from + * @ts: a variable to store the timestamp (may be NULL) + * @lost_events: a variable to store if events were lost (may be NULL) * * Returns the next event in the ring buffer, and that event is consumed. * Meaning, that sequential reads will keep returning a different event, * and eventually empty the ring buffer if the producer is slower. */ struct ring_buffer_event * -ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) +ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts, + unsigned long *lost_events) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_event *event = NULL; @@ -3225,14 +3930,16 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) cpu_buffer = buffer->buffers[cpu]; local_irq_save(flags); if (dolock) - spin_lock(&cpu_buffer->reader_lock); + raw_spin_lock(&cpu_buffer->reader_lock); - event = rb_buffer_peek(cpu_buffer, ts); - if (event) + event = rb_buffer_peek(cpu_buffer, ts, lost_events); + if (event) { + cpu_buffer->lost_events = 0; rb_advance_reader(cpu_buffer); + } if (dolock) - spin_unlock(&cpu_buffer->reader_lock); + raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); out: @@ -3246,23 +3953,30 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) EXPORT_SYMBOL_GPL(ring_buffer_consume); /** - * ring_buffer_read_start - start a non consuming read of the buffer + * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer * @buffer: The ring buffer to read from * @cpu: The cpu buffer to iterate over * - * This starts up an iteration through the buffer. It also disables - * the recording to the buffer until the reading is finished. - * This prevents the reading from being corrupted. This is not - * a consuming read, so a producer is not expected. + * This performs the initial preparations necessary to iterate + * through the buffer. Memory is allocated, buffer recording + * is disabled, and the iterator pointer is returned to the caller. + * + * Disabling buffer recordng prevents the reading from being + * corrupted. This is not a consuming read, so a producer is not + * expected. * - * Must be paired with ring_buffer_finish. + * After a sequence of ring_buffer_read_prepare calls, the user is + * expected to make at least one call to ring_buffer_read_prepare_sync. + * Afterwards, ring_buffer_read_start is invoked to get things going + * for real. + * + * This overall must be paired with ring_buffer_read_finish. */ struct ring_buffer_iter * -ring_buffer_read_start(struct ring_buffer *buffer, int cpu) +ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_iter *iter; - unsigned long flags; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return NULL; @@ -3275,21 +3989,59 @@ ring_buffer_read_start(struct ring_buffer *buffer, int cpu) iter->cpu_buffer = cpu_buffer; + atomic_inc(&buffer->resize_disabled); atomic_inc(&cpu_buffer->record_disabled); + + return iter; +} +EXPORT_SYMBOL_GPL(ring_buffer_read_prepare); + +/** + * ring_buffer_read_prepare_sync - Synchronize a set of prepare calls + * + * All previously invoked ring_buffer_read_prepare calls to prepare + * iterators will be synchronized. Afterwards, read_buffer_read_start + * calls on those iterators are allowed. + */ +void +ring_buffer_read_prepare_sync(void) +{ synchronize_sched(); +} +EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync); + +/** + * ring_buffer_read_start - start a non consuming read of the buffer + * @iter: The iterator returned by ring_buffer_read_prepare + * + * This finalizes the startup of an iteration through the buffer. + * The iterator comes from a call to ring_buffer_read_prepare and + * an intervening ring_buffer_read_prepare_sync must have been + * performed. + * + * Must be paired with ring_buffer_read_finish. + */ +void +ring_buffer_read_start(struct ring_buffer_iter *iter) +{ + struct ring_buffer_per_cpu *cpu_buffer; + unsigned long flags; + + if (!iter) + return; - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + cpu_buffer = iter->cpu_buffer; + + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); arch_spin_lock(&cpu_buffer->lock); rb_iter_reset(iter); arch_spin_unlock(&cpu_buffer->lock); - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); - - return iter; + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } EXPORT_SYMBOL_GPL(ring_buffer_read_start); /** - * ring_buffer_finish - finish reading the iterator of the buffer + * ring_buffer_read_finish - finish reading the iterator of the buffer * @iter: The iterator retrieved by ring_buffer_start * * This re-enables the recording to the buffer, and frees the @@ -3299,8 +4051,20 @@ void ring_buffer_read_finish(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; + unsigned long flags; + + /* + * Ring buffer is disabled from recording, here's a good place + * to check the integrity of the ring buffer. + * Must prevent readers from trying to read, as the check + * clears the HEAD page and readers require it. + */ + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + rb_check_pages(cpu_buffer); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); atomic_dec(&cpu_buffer->record_disabled); + atomic_dec(&cpu_buffer->buffer->resize_disabled); kfree(iter); } EXPORT_SYMBOL_GPL(ring_buffer_read_finish); @@ -3319,7 +4083,7 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; unsigned long flags; - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); again: event = rb_iter_peek(iter, ts); if (!event) @@ -3330,7 +4094,7 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) rb_advance_iter(iter); out: - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); return event; } @@ -3340,9 +4104,18 @@ EXPORT_SYMBOL_GPL(ring_buffer_read); * ring_buffer_size - return the size of the ring buffer (in bytes) * @buffer: The ring buffer. */ -unsigned long ring_buffer_size(struct ring_buffer *buffer) +unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu) { - return BUF_PAGE_SIZE * buffer->pages; + /* + * Earlier, this method returned + * BUF_PAGE_SIZE * buffer->nr_pages + * Since the nr_pages field is now removed, we have converted this to + * return the per cpu buffer value. + */ + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return 0; + + return BUF_PAGE_SIZE * buffer->buffers[cpu]->nr_pages; } EXPORT_SYMBOL_GPL(ring_buffer_size); @@ -3363,21 +4136,28 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->commit_page = cpu_buffer->head_page; INIT_LIST_HEAD(&cpu_buffer->reader_page->list); + INIT_LIST_HEAD(&cpu_buffer->new_pages); local_set(&cpu_buffer->reader_page->write, 0); local_set(&cpu_buffer->reader_page->entries, 0); local_set(&cpu_buffer->reader_page->page->commit, 0); cpu_buffer->reader_page->read = 0; - local_set(&cpu_buffer->commit_overrun, 0); + local_set(&cpu_buffer->entries_bytes, 0); local_set(&cpu_buffer->overrun, 0); + local_set(&cpu_buffer->commit_overrun, 0); + local_set(&cpu_buffer->dropped_events, 0); local_set(&cpu_buffer->entries, 0); local_set(&cpu_buffer->committing, 0); local_set(&cpu_buffer->commits, 0); cpu_buffer->read = 0; + cpu_buffer->read_bytes = 0; cpu_buffer->write_stamp = 0; cpu_buffer->read_stamp = 0; + cpu_buffer->lost_events = 0; + cpu_buffer->last_overrun = 0; + rb_head_page_activate(cpu_buffer); } @@ -3394,9 +4174,13 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) if (!cpumask_test_cpu(cpu, buffer->cpumask)) return; + atomic_inc(&buffer->resize_disabled); atomic_inc(&cpu_buffer->record_disabled); - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + /* Make sure all commits have finished */ + synchronize_sched(); + + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) goto out; @@ -3408,9 +4192,10 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) arch_spin_unlock(&cpu_buffer->lock); out: - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); atomic_dec(&cpu_buffer->record_disabled); + atomic_dec(&buffer->resize_disabled); } EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); @@ -3446,10 +4231,10 @@ int ring_buffer_empty(struct ring_buffer *buffer) cpu_buffer = buffer->buffers[cpu]; local_irq_save(flags); if (dolock) - spin_lock(&cpu_buffer->reader_lock); + raw_spin_lock(&cpu_buffer->reader_lock); ret = rb_per_cpu_empty(cpu_buffer); if (dolock) - spin_unlock(&cpu_buffer->reader_lock); + raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); if (!ret) @@ -3480,10 +4265,10 @@ int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) cpu_buffer = buffer->buffers[cpu]; local_irq_save(flags); if (dolock) - spin_lock(&cpu_buffer->reader_lock); + raw_spin_lock(&cpu_buffer->reader_lock); ret = rb_per_cpu_empty(cpu_buffer); if (dolock) - spin_unlock(&cpu_buffer->reader_lock); + raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); return ret; @@ -3512,8 +4297,11 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, !cpumask_test_cpu(cpu, buffer_b->cpumask)) goto out; + cpu_buffer_a = buffer_a->buffers[cpu]; + cpu_buffer_b = buffer_b->buffers[cpu]; + /* At least make sure the two buffers are somewhat the same */ - if (buffer_a->pages != buffer_b->pages) + if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages) goto out; ret = -EAGAIN; @@ -3527,9 +4315,6 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, if (atomic_read(&buffer_b->record_disabled)) goto out; - cpu_buffer_a = buffer_a->buffers[cpu]; - cpu_buffer_b = buffer_b->buffers[cpu]; - if (atomic_read(&cpu_buffer_a->record_disabled)) goto out; @@ -3571,6 +4356,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); /** * ring_buffer_alloc_read_page - allocate a page to read from buffer * @buffer: the buffer to allocate for. + * @cpu: the cpu buffer to allocate. * * This function is used in conjunction with ring_buffer_read_page. * When reading a full page from the ring buffer, these functions @@ -3583,16 +4369,17 @@ EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); * Returns: * The page allocated, or NULL on error. */ -void *ring_buffer_alloc_read_page(struct ring_buffer *buffer) +void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu) { struct buffer_data_page *bpage; - unsigned long addr; + struct page *page; - addr = __get_free_page(GFP_KERNEL); - if (!addr) + page = alloc_pages_node(cpu_to_node(cpu), + GFP_KERNEL | __GFP_NORETRY, 0); + if (!page) return NULL; - bpage = (void *)addr; + bpage = page_address(page); rb_init_page(bpage); @@ -3627,7 +4414,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); * to swap with a page in the ring buffer. * * for example: - * rpage = ring_buffer_alloc_read_page(buffer); + * rpage = ring_buffer_alloc_read_page(buffer, cpu); * if (!rpage) * return error; * ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0); @@ -3653,6 +4440,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer, struct ring_buffer_event *event; struct buffer_data_page *bpage; struct buffer_page *reader; + unsigned long missed_events; unsigned long flags; unsigned int commit; unsigned int read; @@ -3678,7 +4466,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer, if (!bpage) goto out; - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); reader = rb_get_reader_page(cpu_buffer); if (!reader) @@ -3689,6 +4477,9 @@ int ring_buffer_read_page(struct ring_buffer *buffer, read = reader->read; commit = rb_page_commit(reader); + /* Check if any events were dropped */ + missed_events = cpu_buffer->lost_events; + /* * If this page has been partially read or * if len is not big enough to read the rest of the page or @@ -3709,7 +4500,8 @@ int ring_buffer_read_page(struct ring_buffer *buffer, if (len > (commit - read)) len = (commit - read); - size = rb_event_length(event); + /* Always keep the time extend and data together */ + size = rb_event_ts_length(event); if (len < size) goto out_unlock; @@ -3719,6 +4511,13 @@ int ring_buffer_read_page(struct ring_buffer *buffer, /* Need to copy one event at a time */ do { + /* We need the size of one event, because + * rb_advance_reader only advances by one event, + * whereas rb_event_ts_length may include the size of + * one or two events. + * We have already ensured there's enough space if this + * is a time extend. */ + size = rb_event_length(event); memcpy(bpage->data + pos, rpage->data + rpos, size); len -= size; @@ -3727,9 +4526,13 @@ int ring_buffer_read_page(struct ring_buffer *buffer, rpos = reader->read; pos += size; + if (rpos >= commit) + break; + event = rb_reader_event(cpu_buffer); - size = rb_event_length(event); - } while (len > size); + /* Always keep the time extend and data together */ + size = rb_event_ts_length(event); + } while (len >= size); /* update bpage */ local_set(&bpage->commit, pos); @@ -3740,6 +4543,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer, } else { /* update the entry counter */ cpu_buffer->read += rb_page_entries(reader); + cpu_buffer->read_bytes += BUF_PAGE_SIZE; /* swap the pages */ rb_init_page(bpage); @@ -3749,87 +4553,50 @@ int ring_buffer_read_page(struct ring_buffer *buffer, local_set(&reader->entries, 0); reader->read = 0; *data_page = bpage; + + /* + * Use the real_end for the data size, + * This gives us a chance to store the lost events + * on the page. + */ + if (reader->real_end) + local_set(&bpage->commit, reader->real_end); } ret = read; + cpu_buffer->lost_events = 0; + + commit = local_read(&bpage->commit); + /* + * Set a flag in the commit field if we lost events + */ + if (missed_events) { + /* If there is room at the end of the page to save the + * missed events, then record it there. + */ + if (BUF_PAGE_SIZE - commit >= sizeof(missed_events)) { + memcpy(&bpage->data[commit], &missed_events, + sizeof(missed_events)); + local_add(RB_MISSED_STORED, &bpage->commit); + commit += sizeof(missed_events); + } + local_add(RB_MISSED_EVENTS, &bpage->commit); + } + + /* + * This page may be off to user land. Zero it out here. + */ + if (commit < BUF_PAGE_SIZE) + memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit); + out_unlock: - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); out: return ret; } EXPORT_SYMBOL_GPL(ring_buffer_read_page); -#ifdef CONFIG_TRACING -static ssize_t -rb_simple_read(struct file *filp, char __user *ubuf, - size_t cnt, loff_t *ppos) -{ - unsigned long *p = filp->private_data; - char buf[64]; - int r; - - if (test_bit(RB_BUFFERS_DISABLED_BIT, p)) - r = sprintf(buf, "permanently disabled\n"); - else - r = sprintf(buf, "%d\n", test_bit(RB_BUFFERS_ON_BIT, p)); - - return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); -} - -static ssize_t -rb_simple_write(struct file *filp, const char __user *ubuf, - size_t cnt, loff_t *ppos) -{ - unsigned long *p = filp->private_data; - char buf[64]; - unsigned long val; - int ret; - - if (cnt >= sizeof(buf)) - return -EINVAL; - - if (copy_from_user(&buf, ubuf, cnt)) - return -EFAULT; - - buf[cnt] = 0; - - ret = strict_strtoul(buf, 10, &val); - if (ret < 0) - return ret; - - if (val) - set_bit(RB_BUFFERS_ON_BIT, p); - else - clear_bit(RB_BUFFERS_ON_BIT, p); - - (*ppos)++; - - return cnt; -} - -static const struct file_operations rb_simple_fops = { - .open = tracing_open_generic, - .read = rb_simple_read, - .write = rb_simple_write, -}; - - -static __init int rb_init_debugfs(void) -{ - struct dentry *d_tracer; - - d_tracer = tracing_init_dentry(); - - trace_create_file("tracing_on", 0644, d_tracer, - &ring_buffer_flags, &rb_simple_fops); - - return 0; -} - -fs_initcall(rb_init_debugfs); -#endif - #ifdef CONFIG_HOTPLUG_CPU static int rb_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) @@ -3837,6 +4604,8 @@ static int rb_cpu_notify(struct notifier_block *self, struct ring_buffer *buffer = container_of(self, struct ring_buffer, cpu_notify); long cpu = (long)hcpu; + int cpu_i, nr_pages_same; + unsigned int nr_pages; switch (action) { case CPU_UP_PREPARE: @@ -3844,8 +4613,23 @@ static int rb_cpu_notify(struct notifier_block *self, if (cpumask_test_cpu(cpu, buffer->cpumask)) return NOTIFY_OK; + nr_pages = 0; + nr_pages_same = 1; + /* check if all cpu sizes are same */ + for_each_buffer_cpu(buffer, cpu_i) { + /* fill in the size from first enabled cpu */ + if (nr_pages == 0) + nr_pages = buffer->buffers[cpu_i]->nr_pages; + if (nr_pages != buffer->buffers[cpu_i]->nr_pages) { + nr_pages_same = 0; + break; + } + } + /* allocate minimum pages, user can later expand it */ + if (!nr_pages_same) + nr_pages = 2; buffer->buffers[cpu] = - rb_allocate_cpu_buffer(buffer, cpu); + rb_allocate_cpu_buffer(buffer, nr_pages, cpu); if (!buffer->buffers[cpu]) { WARN(1, "failed to allocate ring buffer on CPU %ld\n", cpu); @@ -3868,3 +4652,320 @@ static int rb_cpu_notify(struct notifier_block *self, return NOTIFY_OK; } #endif + +#ifdef CONFIG_RING_BUFFER_STARTUP_TEST +/* + * This is a basic integrity check of the ring buffer. + * Late in the boot cycle this test will run when configured in. + * It will kick off a thread per CPU that will go into a loop + * writing to the per cpu ring buffer various sizes of data. + * Some of the data will be large items, some small. + * + * Another thread is created that goes into a spin, sending out + * IPIs to the other CPUs to also write into the ring buffer. + * this is to test the nesting ability of the buffer. + * + * Basic stats are recorded and reported. If something in the + * ring buffer should happen that's not expected, a big warning + * is displayed and all ring buffers are disabled. + */ +static struct task_struct *rb_threads[NR_CPUS] __initdata; + +struct rb_test_data { + struct ring_buffer *buffer; + unsigned long events; + unsigned long bytes_written; + unsigned long bytes_alloc; + unsigned long bytes_dropped; + unsigned long events_nested; + unsigned long bytes_written_nested; + unsigned long bytes_alloc_nested; + unsigned long bytes_dropped_nested; + int min_size_nested; + int max_size_nested; + int max_size; + int min_size; + int cpu; + int cnt; +}; + +static struct rb_test_data rb_data[NR_CPUS] __initdata; + +/* 1 meg per cpu */ +#define RB_TEST_BUFFER_SIZE 1048576 + +static char rb_string[] __initdata = + "abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()?+\\" + "?+|:';\",.<>/?abcdefghijklmnopqrstuvwxyz1234567890" + "!@#$%^&*()?+\\?+|:';\",.<>/?abcdefghijklmnopqrstuv"; + +static bool rb_test_started __initdata; + +struct rb_item { + int size; + char str[]; +}; + +static __init int rb_write_something(struct rb_test_data *data, bool nested) +{ + struct ring_buffer_event *event; + struct rb_item *item; + bool started; + int event_len; + int size; + int len; + int cnt; + + /* Have nested writes different that what is written */ + cnt = data->cnt + (nested ? 27 : 0); + + /* Multiply cnt by ~e, to make some unique increment */ + size = (data->cnt * 68 / 25) % (sizeof(rb_string) - 1); + + len = size + sizeof(struct rb_item); + + started = rb_test_started; + /* read rb_test_started before checking buffer enabled */ + smp_rmb(); + + event = ring_buffer_lock_reserve(data->buffer, len); + if (!event) { + /* Ignore dropped events before test starts. */ + if (started) { + if (nested) + data->bytes_dropped += len; + else + data->bytes_dropped_nested += len; + } + return len; + } + + event_len = ring_buffer_event_length(event); + + if (RB_WARN_ON(data->buffer, event_len < len)) + goto out; + + item = ring_buffer_event_data(event); + item->size = size; + memcpy(item->str, rb_string, size); + + if (nested) { + data->bytes_alloc_nested += event_len; + data->bytes_written_nested += len; + data->events_nested++; + if (!data->min_size_nested || len < data->min_size_nested) + data->min_size_nested = len; + if (len > data->max_size_nested) + data->max_size_nested = len; + } else { + data->bytes_alloc += event_len; + data->bytes_written += len; + data->events++; + if (!data->min_size || len < data->min_size) + data->max_size = len; + if (len > data->max_size) + data->max_size = len; + } + + out: + ring_buffer_unlock_commit(data->buffer, event); + + return 0; +} + +static __init int rb_test(void *arg) +{ + struct rb_test_data *data = arg; + + while (!kthread_should_stop()) { + rb_write_something(data, false); + data->cnt++; + + set_current_state(TASK_INTERRUPTIBLE); + /* Now sleep between a min of 100-300us and a max of 1ms */ + usleep_range(((data->cnt % 3) + 1) * 100, 1000); + } + + return 0; +} + +static __init void rb_ipi(void *ignore) +{ + struct rb_test_data *data; + int cpu = smp_processor_id(); + + data = &rb_data[cpu]; + rb_write_something(data, true); +} + +static __init int rb_hammer_test(void *arg) +{ + while (!kthread_should_stop()) { + + /* Send an IPI to all cpus to write data! */ + smp_call_function(rb_ipi, NULL, 1); + /* No sleep, but for non preempt, let others run */ + schedule(); + } + + return 0; +} + +static __init int test_ringbuffer(void) +{ + struct task_struct *rb_hammer; + struct ring_buffer *buffer; + int cpu; + int ret = 0; + + pr_info("Running ring buffer tests...\n"); + + buffer = ring_buffer_alloc(RB_TEST_BUFFER_SIZE, RB_FL_OVERWRITE); + if (WARN_ON(!buffer)) + return 0; + + /* Disable buffer so that threads can't write to it yet */ + ring_buffer_record_off(buffer); + + for_each_online_cpu(cpu) { + rb_data[cpu].buffer = buffer; + rb_data[cpu].cpu = cpu; + rb_data[cpu].cnt = cpu; + rb_threads[cpu] = kthread_create(rb_test, &rb_data[cpu], + "rbtester/%d", cpu); + if (WARN_ON(!rb_threads[cpu])) { + pr_cont("FAILED\n"); + ret = -1; + goto out_free; + } + + kthread_bind(rb_threads[cpu], cpu); + wake_up_process(rb_threads[cpu]); + } + + /* Now create the rb hammer! */ + rb_hammer = kthread_run(rb_hammer_test, NULL, "rbhammer"); + if (WARN_ON(!rb_hammer)) { + pr_cont("FAILED\n"); + ret = -1; + goto out_free; + } + + ring_buffer_record_on(buffer); + /* + * Show buffer is enabled before setting rb_test_started. + * Yes there's a small race window where events could be + * dropped and the thread wont catch it. But when a ring + * buffer gets enabled, there will always be some kind of + * delay before other CPUs see it. Thus, we don't care about + * those dropped events. We care about events dropped after + * the threads see that the buffer is active. + */ + smp_wmb(); + rb_test_started = true; + + set_current_state(TASK_INTERRUPTIBLE); + /* Just run for 10 seconds */; + schedule_timeout(10 * HZ); + + kthread_stop(rb_hammer); + + out_free: + for_each_online_cpu(cpu) { + if (!rb_threads[cpu]) + break; + kthread_stop(rb_threads[cpu]); + } + if (ret) { + ring_buffer_free(buffer); + return ret; + } + + /* Report! */ + pr_info("finished\n"); + for_each_online_cpu(cpu) { + struct ring_buffer_event *event; + struct rb_test_data *data = &rb_data[cpu]; + struct rb_item *item; + unsigned long total_events; + unsigned long total_dropped; + unsigned long total_written; + unsigned long total_alloc; + unsigned long total_read = 0; + unsigned long total_size = 0; + unsigned long total_len = 0; + unsigned long total_lost = 0; + unsigned long lost; + int big_event_size; + int small_event_size; + + ret = -1; + + total_events = data->events + data->events_nested; + total_written = data->bytes_written + data->bytes_written_nested; + total_alloc = data->bytes_alloc + data->bytes_alloc_nested; + total_dropped = data->bytes_dropped + data->bytes_dropped_nested; + + big_event_size = data->max_size + data->max_size_nested; + small_event_size = data->min_size + data->min_size_nested; + + pr_info("CPU %d:\n", cpu); + pr_info(" events: %ld\n", total_events); + pr_info(" dropped bytes: %ld\n", total_dropped); + pr_info(" alloced bytes: %ld\n", total_alloc); + pr_info(" written bytes: %ld\n", total_written); + pr_info(" biggest event: %d\n", big_event_size); + pr_info(" smallest event: %d\n", small_event_size); + + if (RB_WARN_ON(buffer, total_dropped)) + break; + + ret = 0; + + while ((event = ring_buffer_consume(buffer, cpu, NULL, &lost))) { + total_lost += lost; + item = ring_buffer_event_data(event); + total_len += ring_buffer_event_length(event); + total_size += item->size + sizeof(struct rb_item); + if (memcmp(&item->str[0], rb_string, item->size) != 0) { + pr_info("FAILED!\n"); + pr_info("buffer had: %.*s\n", item->size, item->str); + pr_info("expected: %.*s\n", item->size, rb_string); + RB_WARN_ON(buffer, 1); + ret = -1; + break; + } + total_read++; + } + if (ret) + break; + + ret = -1; + + pr_info(" read events: %ld\n", total_read); + pr_info(" lost events: %ld\n", total_lost); + pr_info(" total events: %ld\n", total_lost + total_read); + pr_info(" recorded len bytes: %ld\n", total_len); + pr_info(" recorded size bytes: %ld\n", total_size); + if (total_lost) + pr_info(" With dropped events, record len and size may not match\n" + " alloced and written from above\n"); + if (!total_lost) { + if (RB_WARN_ON(buffer, total_len != total_alloc || + total_size != total_written)) + break; + } + if (RB_WARN_ON(buffer, total_lost + total_read != total_events)) + break; + + ret = 0; + } + if (!ret) + pr_info("Ring buffer PASSED!\n"); + + ring_buffer_free(buffer); + return 0; +} + +late_initcall(test_ringbuffer); +#endif /* CONFIG_RING_BUFFER_STARTUP_TEST */ |