diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-03-31 13:34:04 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-03-31 13:34:04 -0700 |
commit | f187e9fd68577cdd5f914659b6f7f11124e40485 (patch) | |
tree | ad0e7422359724f7c7ffaaaa80dd3a7281f02a83 | |
parent | adb3b1f3fc1c6edb501808ebf80a81e81c52eb73 (diff) | |
parent | 8ebfdf2babcda5a3b06cc67523bca1f9aed46009 (diff) |
Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates and fixes from Ingo Molnar:
"It's mostly fixes, but there's also two late items:
- preliminary GTK GUI support for perf report
- PMU raw event format descriptors in sysfs, to be parsed by tooling
The raw event format in sysfs is a new ABI. For example for the 'CPU'
PMU we have:
aldebaran:~> ll /sys/bus/event_source/devices/cpu/format/*
-r--r--r--. 1 root root 4096 Mar 31 10:29 /sys/bus/event_source/devices/cpu/format/any
-r--r--r--. 1 root root 4096 Mar 31 10:29 /sys/bus/event_source/devices/cpu/format/cmask
-r--r--r--. 1 root root 4096 Mar 31 10:29 /sys/bus/event_source/devices/cpu/format/edge
-r--r--r--. 1 root root 4096 Mar 31 10:29 /sys/bus/event_source/devices/cpu/format/event
-r--r--r--. 1 root root 4096 Mar 31 10:29 /sys/bus/event_source/devices/cpu/format/inv
-r--r--r--. 1 root root 4096 Mar 31 10:29 /sys/bus/event_source/devices/cpu/format/offcore_rsp
-r--r--r--. 1 root root 4096 Mar 31 10:29 /sys/bus/event_source/devices/cpu/format/pc
-r--r--r--. 1 root root 4096 Mar 31 10:29 /sys/bus/event_source/devices/cpu/format/umask
those lists of fields contain a specific format:
aldebaran:~> cat /sys/bus/event_source/devices/cpu/format/offcore_rsp
config1:0-63
So, those who wish to specify raw events can now use the following
event format:
-e cpu/cmask=1,event=2,umask=3
Most people will not want to specify any events (let alone raw
events), they'll just use whatever default event the tools use.
But for more obscure PMU events that have no cross-architecture
generic events the above syntax is more usable and a bit more
structured than specifying hex numbers."
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits)
perf tools: Remove auto-generated bison/flex files
perf annotate: Fix off by one symbol hist size allocation and hit accounting
perf tools: Add missing ref-cycles event back to event parser
perf annotate: addr2line wants addresses in same format as objdump
perf probe: Finder fails to resolve function name to address
tracing: Fix ent_size in trace output
perf symbols: Handle NULL dso in dso__name_len
perf symbols: Do not include libgen.h
perf tools: Fix bug in raw sample parsing
perf tools: Fix display of first level of callchains
perf tools: Switch module.h into export.h
perf: Move mmap page data_head offset assertion out of header
perf: Fix mmap_page capabilities and docs
perf diff: Fix to work with new hists design
perf tools: Fix modifier to be applied on correct events
perf tools: Fix various casting issues for 32 bits
perf tools: Simplify event_read_id exit path
tracing: Fix ftrace stack trace entries
tracing: Move the tracing_on/off() declarations into CONFIG_TRACING
perf report: Add a simple GTK2-based 'perf report' browser
...
52 files changed, 2531 insertions, 584 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-event_source-devices-format b/Documentation/ABI/testing/sysfs-bus-event_source-devices-format new file mode 100644 index 00000000000..079afc71363 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-event_source-devices-format @@ -0,0 +1,14 @@ +Where: /sys/bus/event_source/devices/<dev>/format +Date: January 2012 +Kernel Version: 3.3 +Contact: Jiri Olsa <jolsa@redhat.com> +Description: + Attribute group to describe the magic bits that go into + perf_event_attr::config[012] for a particular pmu. + Each attribute of this group defines the 'hardware' bitmask + we want to export, so that userspace can deal with sane + name/value pairs. + + Example: 'config1:1,6-10,44' + Defines contents of attribute that occupies bits 1,6-10,44 of + perf_event_attr::config1. diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 40883ffe2da..bb8e03407e1 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -1313,6 +1313,11 @@ static void __init pmu_check_apic(void) pr_info("no hardware sampling interrupt available.\n"); } +static struct attribute_group x86_pmu_format_group = { + .name = "format", + .attrs = NULL, +}; + static int __init init_hw_perf_events(void) { struct x86_pmu_quirk *quirk; @@ -1387,6 +1392,7 @@ static int __init init_hw_perf_events(void) } x86_pmu.attr_rdpmc = 1; /* enable userspace RDPMC usage by default */ + x86_pmu_format_group.attrs = x86_pmu.format_attrs; pr_info("... version: %d\n", x86_pmu.version); pr_info("... bit width: %d\n", x86_pmu.cntval_bits); @@ -1615,6 +1621,9 @@ static int x86_pmu_event_idx(struct perf_event *event) { int idx = event->hw.idx; + if (!x86_pmu.attr_rdpmc) + return 0; + if (x86_pmu.num_counters_fixed && idx >= X86_PMC_IDX_FIXED) { idx -= X86_PMC_IDX_FIXED; idx |= 1 << 30; @@ -1667,6 +1676,7 @@ static struct attribute_group x86_pmu_attr_group = { static const struct attribute_group *x86_pmu_attr_groups[] = { &x86_pmu_attr_group, + &x86_pmu_format_group, NULL, }; @@ -1698,14 +1708,19 @@ static struct pmu pmu = { .flush_branch_stack = x86_pmu_flush_branch_stack, }; -void perf_update_user_clock(struct perf_event_mmap_page *userpg, u64 now) +void arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now) { + userpg->cap_usr_time = 0; + userpg->cap_usr_rdpmc = x86_pmu.attr_rdpmc; + userpg->pmc_width = x86_pmu.cntval_bits; + if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) return; if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) return; + userpg->cap_usr_time = 1; userpg->time_mult = this_cpu_read(cyc2ns); userpg->time_shift = CYC2NS_SCALE_FACTOR; userpg->time_offset = this_cpu_read(cyc2ns_offset) - now; diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h index 8484e77c211..6638aaf5449 100644 --- a/arch/x86/kernel/cpu/perf_event.h +++ b/arch/x86/kernel/cpu/perf_event.h @@ -339,6 +339,7 @@ struct x86_pmu { * sysfs attrs */ int attr_rdpmc; + struct attribute **format_attrs; /* * CPU Hotplug hooks diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c index dd002faff7a..95e7fe1c5f0 100644 --- a/arch/x86/kernel/cpu/perf_event_amd.c +++ b/arch/x86/kernel/cpu/perf_event_amd.c @@ -404,6 +404,21 @@ static void amd_pmu_cpu_dead(int cpu) } } +PMU_FORMAT_ATTR(event, "config:0-7,32-35"); +PMU_FORMAT_ATTR(umask, "config:8-15" ); +PMU_FORMAT_ATTR(edge, "config:18" ); +PMU_FORMAT_ATTR(inv, "config:23" ); +PMU_FORMAT_ATTR(cmask, "config:24-31" ); + +static struct attribute *amd_format_attr[] = { + &format_attr_event.attr, + &format_attr_umask.attr, + &format_attr_edge.attr, + &format_attr_inv.attr, + &format_attr_cmask.attr, + NULL, +}; + static __initconst const struct x86_pmu amd_pmu = { .name = "AMD", .handle_irq = x86_pmu_handle_irq, @@ -426,6 +441,8 @@ static __initconst const struct x86_pmu amd_pmu = { .get_event_constraints = amd_get_event_constraints, .put_event_constraints = amd_put_event_constraints, + .format_attrs = amd_format_attr, + .cpu_prepare = amd_pmu_cpu_prepare, .cpu_starting = amd_pmu_cpu_starting, .cpu_dead = amd_pmu_cpu_dead, @@ -596,6 +613,7 @@ static __initconst const struct x86_pmu amd_pmu_f15h = { .cpu_dead = amd_pmu_cpu_dead, #endif .cpu_starting = amd_pmu_cpu_starting, + .format_attrs = amd_format_attr, }; __init int amd_pmu_init(void) diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index 6a84e7f28f0..26b3e2fef10 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1431,6 +1431,24 @@ static void core_pmu_enable_all(int added) } } +PMU_FORMAT_ATTR(event, "config:0-7" ); +PMU_FORMAT_ATTR(umask, "config:8-15" ); +PMU_FORMAT_ATTR(edge, "config:18" ); +PMU_FORMAT_ATTR(pc, "config:19" ); +PMU_FORMAT_ATTR(any, "config:21" ); /* v3 + */ +PMU_FORMAT_ATTR(inv, "config:23" ); +PMU_FORMAT_ATTR(cmask, "config:24-31" ); + +static struct attribute *intel_arch_formats_attr[] = { + &format_attr_event.attr, + &format_attr_umask.attr, + &format_attr_edge.attr, + &format_attr_pc.attr, + &format_attr_inv.attr, + &format_attr_cmask.attr, + NULL, +}; + static __initconst const struct x86_pmu core_pmu = { .name = "core", .handle_irq = x86_pmu_handle_irq, @@ -1455,6 +1473,7 @@ static __initconst const struct x86_pmu core_pmu = { .put_event_constraints = intel_put_event_constraints, .event_constraints = intel_core_event_constraints, .guest_get_msrs = core_guest_get_msrs, + .format_attrs = intel_arch_formats_attr, }; struct intel_shared_regs *allocate_shared_regs(int cpu) @@ -1553,6 +1572,21 @@ static void intel_pmu_flush_branch_stack(void) intel_pmu_lbr_reset(); } +PMU_FORMAT_ATTR(offcore_rsp, "config1:0-63"); + +static struct attribute *intel_arch3_formats_attr[] = { + &format_attr_event.attr, + &format_attr_umask.attr, + &format_attr_edge.attr, + &format_attr_pc.attr, + &format_attr_any.attr, + &format_attr_inv.attr, + &format_attr_cmask.attr, + + &format_attr_offcore_rsp.attr, /* XXX do NHM/WSM + SNB breakout */ + NULL, +}; + static __initconst const struct x86_pmu intel_pmu = { .name = "Intel", .handle_irq = intel_pmu_handle_irq, @@ -1576,6 +1610,8 @@ static __initconst const struct x86_pmu intel_pmu = { .get_event_constraints = intel_get_event_constraints, .put_event_constraints = intel_put_event_constraints, + .format_attrs = intel_arch3_formats_attr, + .cpu_prepare = intel_pmu_cpu_prepare, .cpu_starting = intel_pmu_cpu_starting, .cpu_dying = intel_pmu_cpu_dying, diff --git a/arch/x86/kernel/cpu/perf_event_p6.c b/arch/x86/kernel/cpu/perf_event_p6.c index c7181befecd..32bcfc7dd23 100644 --- a/arch/x86/kernel/cpu/perf_event_p6.c +++ b/arch/x86/kernel/cpu/perf_event_p6.c @@ -87,6 +87,23 @@ static void p6_pmu_enable_event(struct perf_event *event) (void)checking_wrmsrl(hwc->config_base, val); } +PMU_FORMAT_ATTR(event, "config:0-7" ); +PMU_FORMAT_ATTR(umask, "config:8-15" ); +PMU_FORMAT_ATTR(edge, "config:18" ); +PMU_FORMAT_ATTR(pc, "config:19" ); +PMU_FORMAT_ATTR(inv, "config:23" ); +PMU_FORMAT_ATTR(cmask, "config:24-31" ); + +static struct attribute *intel_p6_formats_attr[] = { + &format_attr_event.attr, + &format_attr_umask.attr, + &format_attr_edge.attr, + &format_attr_pc.attr, + &format_attr_inv.attr, + &format_attr_cmask.attr, + NULL, +}; + static __initconst const struct x86_pmu p6_pmu = { .name = "p6", .handle_irq = x86_pmu_handle_irq, @@ -115,6 +132,8 @@ static __initconst const struct x86_pmu p6_pmu = { .cntval_mask = (1ULL << 32) - 1, .get_event_constraints = x86_get_event_constraints, .event_constraints = p6_event_constraints, + + .format_attrs = intel_p6_formats_attr, }; __init int p6_pmu_init(void) diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index dd478fc8f9f..5f3f3be5af0 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -144,12 +144,14 @@ struct event_filter; enum trace_reg { TRACE_REG_REGISTER, TRACE_REG_UNREGISTER, +#ifdef CONFIG_PERF_EVENTS TRACE_REG_PERF_REGISTER, TRACE_REG_PERF_UNREGISTER, TRACE_REG_PERF_OPEN, TRACE_REG_PERF_CLOSE, TRACE_REG_PERF_ADD, TRACE_REG_PERF_DEL, +#endif }; struct ftrace_event_call; diff --git a/include/linux/kernel.h b/include/linux/kernel.h index a5375e7f3fe..645231c373c 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -430,16 +430,10 @@ extern int __must_check hex2bin(u8 *dst, const char *src, size_t count); * Most likely, you want to use tracing_on/tracing_off. */ #ifdef CONFIG_RING_BUFFER -void tracing_on(void); -void tracing_off(void); /* trace_off_permanent stops recording with no way to bring it back */ void tracing_off_permanent(void); -int tracing_is_on(void); #else -static inline void tracing_on(void) { } -static inline void tracing_off(void) { } static inline void tracing_off_permanent(void) { } -static inline int tracing_is_on(void) { return 0; } #endif enum ftrace_dump_mode { @@ -449,6 +443,10 @@ enum ftrace_dump_mode { }; #ifdef CONFIG_TRACING +void tracing_on(void); +void tracing_off(void); +int tracing_is_on(void); + extern void tracing_start(void); extern void tracing_stop(void); extern void ftrace_off_permanent(void); @@ -533,6 +531,11 @@ static inline void tracing_start(void) { } static inline void tracing_stop(void) { } static inline void ftrace_off_permanent(void) { } static inline void trace_dump_stack(void) { } + +static inline void tracing_on(void) { } +static inline void tracing_off(void) { } +static inline int tracing_is_on(void) { return 0; } + static inline int trace_printk(const char *fmt, ...) { diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index bd9f55a5958..ddbb6a901f6 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -299,18 +299,31 @@ struct perf_event_mmap_page { /* * Bits needed to read the hw events in user-space. * - * u32 seq; - * s64 count; + * u32 seq, time_mult, time_shift, idx, width; + * u64 count, enabled, running; + * u64 cyc, time_offset; + * s64 pmc = 0; * * do { * seq = pc->lock; - * * barrier() - * if (pc->index) { - * count = pmc_read(pc->index - 1); - * count += pc->offset; - * } else - * goto regular_read; + * + * enabled = pc->time_enabled; + * running = pc->time_running; + * + * if (pc->cap_usr_time && enabled != running) { + * cyc = rdtsc(); + * time_offset = pc->time_offset; + * time_mult = pc->time_mult; + * time_shift = pc->time_shift; + * } + * + * idx = pc->index; + * count = pc->offset; + * if (pc->cap_usr_rdpmc && idx) { + * width = pc->pmc_width; + * pmc = rdpmc(idx - 1); + * } * * barrier(); * } while (pc->lock != seq); @@ -323,14 +336,57 @@ struct perf_event_mmap_page { __s64 offset; /* add to hardware event value */ __u64 time_enabled; /* time event active */ __u64 time_running; /* time event on cpu */ - __u32 time_mult, time_shift; + union { + __u64 capabilities; + __u64 cap_usr_time : 1, + cap_usr_rdpmc : 1, + cap_____res : 62; + }; + + /* + * If cap_usr_rdpmc this field provides the bit-width of the value + * read using the rdpmc() or equivalent instruction. This can be used + * to sign extend the result like: + * + * pmc <<= 64 - width; + * pmc >>= 64 - width; // signed shift right + * count += pmc; + */ + __u16 pmc_width; + + /* + * If cap_usr_time the below fields can be used to compute the time + * delta since time_enabled (in ns) using rdtsc or similar. + * + * u64 quot, rem; + * u64 delta; + * + * quot = (cyc >> time_shift); + * rem = cyc & ((1 << time_shift) - 1); + * delta = time_offset + quot * time_mult + + * ((rem * time_mult) >> time_shift); + * + * Where time_offset,time_mult,time_shift and cyc are read in the + * seqcount loop described above. This delta can then be added to + * enabled and possible running (if idx), improving the scaling: + * + * enabled += delta; + * if (idx) + * running += delta; + * + * quot = count / running; + * rem = count % running; + * count = quot * enabled + (rem * enabled) / running; + */ + __u16 time_shift; + __u32 time_mult; __u64 time_offset; /* * Hole for extension of the self monitor capabilities */ - __u64 __reserved[121]; /* align to 1k */ + __u64 __reserved[120]; /* align to 1k */ /* * Control data for the mmap() data buffer. @@ -550,6 +606,7 @@ struct perf_guest_info_callbacks { #include <linux/irq_work.h> #include <linux/static_key.h> #include <linux/atomic.h> +#include <linux/sysfs.h> #include <asm/local.h> #define PERF_MAX_STACK_DEPTH 255 @@ -1291,5 +1348,18 @@ do { \ register_cpu_notifier(&fn##_nb); \ } while (0) + +#define PMU_FORMAT_ATTR(_name, _format) \ +static ssize_t \ +_name##_show(struct device *dev, \ + struct device_attribute *attr, \ + char *page) \ +{ \ + BUILD_BUG_ON(sizeof(_format) >= PAGE_SIZE); \ + return sprintf(page, _format "\n"); \ +} \ + \ +static struct device_attribute format_attr_##_name = __ATTR_RO(_name) + #endif /* __KERNEL__ */ #endif /* _LINUX_PERF_EVENT_H */ diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 67be0376d8e..7be2e88f23f 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -151,6 +151,9 @@ int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu); void ring_buffer_record_disable(struct ring_buffer *buffer); void ring_buffer_record_enable(struct ring_buffer *buffer); +void ring_buffer_record_off(struct ring_buffer *buffer); +void ring_buffer_record_on(struct ring_buffer *buffer); +int ring_buffer_record_is_on(struct ring_buffer *buffer); void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu); void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu); diff --git a/kernel/events/core.c b/kernel/events/core.c index 4b50357914f..a6a9ec4cd8f 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3348,7 +3348,7 @@ static void calc_timer_values(struct perf_event *event, *running = ctx_time - event->tstamp_running; } -void __weak perf_update_user_clock(struct perf_event_mmap_page *userpg, u64 now) +void __weak arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now) { } @@ -3398,7 +3398,7 @@ void perf_event_update_userpage(struct perf_event *event) userpg->time_running = running + atomic64_read(&event->child_total_time_running); - perf_update_user_clock(userpg, now); + arch_perf_update_userpage(userpg, now); barrier(); ++userpg->lock; @@ -7116,6 +7116,13 @@ void __init perf_event_init(void) /* do not patch jump label more than once per second */ jump_label_rate_limit(&perf_sched_events, HZ); + + /* + * Build time assertion that we keep the data_head at the intended + * location. IOW, validation we got the __reserved[] size right. + */ + BUILD_BUG_ON((offsetof(struct perf_event_mmap_page, data_head)) + != 1024); } static int __init perf_event_sysfs_init(void) diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index cd3134510f3..a1d2849f247 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -141,7 +141,7 @@ if FTRACE config FUNCTION_TRACER bool "Kernel Function Tracer" depends on HAVE_FUNCTION_TRACER - select FRAME_POINTER if !ARM_UNWIND && !S390 && !MICROBLAZE + select FRAME_POINTER if !ARM_UNWIND && !PPC && !S390 && !MICROBLAZE select KALLSYMS select GENERIC_TRACER select CONTEXT_SWITCH_TRACER diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 867bd1dd2dd..0fa92f677c9 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -249,7 +249,8 @@ static void update_ftrace_function(void) #else __ftrace_trace_function = func; #endif - ftrace_trace_function = ftrace_test_stop_func; + ftrace_trace_function = + (func == ftrace_stub) ? func : ftrace_test_stop_func; #endif } diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index f5b7b5c1195..cf8d11e91ef 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -154,33 +154,10 @@ enum { static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; -#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) - -/** - * 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); +/* Used for individual buffers (after the counter) */ +#define RB_BUFFER_OFF (1 << 20) -/** - * 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 @@ -193,15 +170,6 @@ 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) @@ -2619,6 +2587,63 @@ 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() verison + * 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; + } wh |