diff options
Diffstat (limited to 'kernel/timer.c')
| -rw-r--r-- | kernel/timer.c | 367 |
1 files changed, 124 insertions, 243 deletions
diff --git a/kernel/timer.c b/kernel/timer.c index 8c5e7b908c6..3bb01a323b2 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1,7 +1,7 @@ /* * linux/kernel/timer.c * - * Kernel internal timers, basic process system calls + * Kernel internal timers * * Copyright (C) 1991, 1992 Linus Torvalds * @@ -39,7 +39,9 @@ #include <linux/kallsyms.h> #include <linux/irq_work.h> #include <linux/sched.h> +#include <linux/sched/sysctl.h> #include <linux/slab.h> +#include <linux/compat.h> #include <asm/uaccess.h> #include <asm/unistd.h> @@ -50,7 +52,7 @@ #define CREATE_TRACE_POINTS #include <trace/events/timer.h> -u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES; +__visible u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES; EXPORT_SYMBOL(jiffies_64); @@ -63,6 +65,7 @@ EXPORT_SYMBOL(jiffies_64); #define TVR_SIZE (1 << TVR_BITS) #define TVN_MASK (TVN_SIZE - 1) #define TVR_MASK (TVR_SIZE - 1) +#define MAX_TVAL ((unsigned long)((1ULL << (TVR_BITS + 4*TVN_BITS)) - 1)) struct tvec { struct list_head vec[TVN_SIZE]; @@ -78,6 +81,7 @@ struct tvec_base { unsigned long timer_jiffies; unsigned long next_timer; unsigned long active_timers; + unsigned long all_timers; struct tvec_root tv1; struct tvec tv2; struct tvec tv3; @@ -92,24 +96,25 @@ static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases; /* Functions below help us manage 'deferrable' flag */ static inline unsigned int tbase_get_deferrable(struct tvec_base *base) { - return ((unsigned int)(unsigned long)base & TBASE_DEFERRABLE_FLAG); + return ((unsigned int)(unsigned long)base & TIMER_DEFERRABLE); } -static inline struct tvec_base *tbase_get_base(struct tvec_base *base) +static inline unsigned int tbase_get_irqsafe(struct tvec_base *base) { - return ((struct tvec_base *)((unsigned long)base & ~TBASE_DEFERRABLE_FLAG)); + return ((unsigned int)(unsigned long)base & TIMER_IRQSAFE); } -static inline void timer_set_deferrable(struct timer_list *timer) +static inline struct tvec_base *tbase_get_base(struct tvec_base *base) { - timer->base = TBASE_MAKE_DEFERRED(timer->base); + return ((struct tvec_base *)((unsigned long)base & ~TIMER_FLAG_MASK)); } static inline void timer_set_base(struct timer_list *timer, struct tvec_base *new_base) { - timer->base = (struct tvec_base *)((unsigned long)(new_base) | - tbase_get_deferrable(timer->base)); + unsigned long flags = (unsigned long)timer->base & TIMER_FLAG_MASK; + + timer->base = (struct tvec_base *)((unsigned long)(new_base) | flags); } static unsigned long round_jiffies_common(unsigned long j, int cpu, @@ -145,9 +150,11 @@ static unsigned long round_jiffies_common(unsigned long j, int cpu, /* now that we have rounded, subtract the extra skew again */ j -= cpu * 3; - if (j <= jiffies) /* rounding ate our timeout entirely; */ - return original; - return j; + /* + * Make sure j is still in the future. Otherwise return the + * unmodified value. + */ + return time_is_after_jiffies(j) ? j : original; } /** @@ -331,6 +338,20 @@ void set_timer_slack(struct timer_list *timer, int slack_hz) } EXPORT_SYMBOL_GPL(set_timer_slack); +/* + * If the list is empty, catch up ->timer_jiffies to the current time. + * The caller must hold the tvec_base lock. Returns true if the list + * was empty and therefore ->timer_jiffies was updated. + */ +static bool catchup_timer_jiffies(struct tvec_base *base) +{ + if (!base->all_timers) { + base->timer_jiffies = jiffies; + return true; + } + return false; +} + static void __internal_add_timer(struct tvec_base *base, struct timer_list *timer) { @@ -358,11 +379,12 @@ __internal_add_timer(struct tvec_base *base, struct timer_list *timer) vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK); } else { int i; - /* If the timeout is larger than 0xffffffff on 64-bit - * architectures then we use the maximum timeout: + /* If the timeout is larger than MAX_TVAL (on 64-bit + * architectures or with CONFIG_BASE_SMALL=1) then we + * use the maximum timeout. */ - if (idx > 0xffffffffUL) { - idx = 0xffffffffUL; + if (idx > MAX_TVAL) { + idx = MAX_TVAL; expires = idx + base->timer_jiffies; } i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK; @@ -376,15 +398,17 @@ __internal_add_timer(struct tvec_base *base, struct timer_list *timer) static void internal_add_timer(struct tvec_base *base, struct timer_list *timer) { + (void)catchup_timer_jiffies(base); __internal_add_timer(base, timer); /* * Update base->active_timers and base->next_timer */ if (!tbase_get_deferrable(timer->base)) { - if (time_before(timer->expires, base->next_timer)) + if (!base->active_timers++ || + time_before(timer->expires, base->next_timer)) base->next_timer = timer->expires; - base->active_timers++; } + base->all_timers++; } #ifdef CONFIG_TIMER_STATS @@ -563,16 +587,14 @@ static inline void debug_timer_assert_init(struct timer_list *timer) debug_object_assert_init(timer, &timer_debug_descr); } -static void __init_timer(struct timer_list *timer, - const char *name, - struct lock_class_key *key); +static void do_init_timer(struct timer_list *timer, unsigned int flags, + const char *name, struct lock_class_key *key); -void init_timer_on_stack_key(struct timer_list *timer, - const char *name, - struct lock_class_key *key) +void init_timer_on_stack_key(struct timer_list *timer, unsigned int flags, + const char *name, struct lock_class_key *key) { debug_object_init_on_stack(timer, &timer_debug_descr); - __init_timer(timer, name, key); + do_init_timer(timer, flags, name, key); } EXPORT_SYMBOL_GPL(init_timer_on_stack_key); @@ -613,12 +635,13 @@ static inline void debug_assert_init(struct timer_list *timer) debug_timer_assert_init(timer); } -static void __init_timer(struct timer_list *timer, - const char *name, - struct lock_class_key *key) +static void do_init_timer(struct timer_list *timer, unsigned int flags, + const char *name, struct lock_class_key *key) { + struct tvec_base *base = __raw_get_cpu_var(tvec_bases); + timer->entry.next = NULL; - timer->base = __raw_get_cpu_var(tvec_bases); + timer->base = (void *)((unsigned long)base | flags); timer->slack = -1; #ifdef CONFIG_TIMER_STATS timer->start_site = NULL; @@ -628,22 +651,10 @@ static void __init_timer(struct timer_list *timer, lockdep_init_map(&timer->lockdep_map, name, key, 0); } -void setup_deferrable_timer_on_stack_key(struct timer_list *timer, - const char *name, - struct lock_class_key *key, - void (*function)(unsigned long), - unsigned long data) -{ - timer->function = function; - timer->data = data; - init_timer_on_stack_key(timer, name, key); - timer_set_deferrable(timer); -} -EXPORT_SYMBOL_GPL(setup_deferrable_timer_on_stack_key); - /** * init_timer_key - initialize a timer * @timer: the timer to be initialized + * @flags: timer flags * @name: name of the timer * @key: lockdep class key of the fake lock used for tracking timer * sync lock dependencies @@ -651,24 +662,14 @@ EXPORT_SYMBOL_GPL(setup_deferrable_timer_on_stack_key); * init_timer_key() must be done to a timer prior calling *any* of the * other timer functions. */ -void init_timer_key(struct timer_list *timer, - const char *name, - struct lock_class_key *key) +void init_timer_key(struct timer_list *timer, unsigned int flags, + const char *name, struct lock_class_key *key) { debug_init(timer); - __init_timer(timer, name, key); + do_init_timer(timer, flags, name, key); } EXPORT_SYMBOL(init_timer_key); -void init_timer_deferrable_key(struct timer_list *timer, - const char *name, - struct lock_class_key *key) -{ - init_timer_key(timer, name, key); - timer_set_deferrable(timer); -} -EXPORT_SYMBOL(init_timer_deferrable_key); - static inline void detach_timer(struct timer_list *timer, bool clear_pending) { struct list_head *entry = &timer->entry; @@ -686,7 +687,9 @@ detach_expired_timer(struct timer_list *timer, struct tvec_base *base) { detach_timer(timer, true); if (!tbase_get_deferrable(timer->base)) - timer->base->active_timers--; + base->active_timers--; + base->all_timers--; + (void)catchup_timer_jiffies(base); } static int detach_if_pending(struct timer_list *timer, struct tvec_base *base, @@ -697,10 +700,12 @@ static int detach_if_pending(struct timer_list *timer, struct tvec_base *base, detach_timer(timer, clear_pending); if (!tbase_get_deferrable(timer->base)) { - timer->base->active_timers--; + base->active_timers--; if (timer->expires == base->next_timer) base->next_timer = base->timer_jiffies; } + base->all_timers--; + (void)catchup_timer_jiffies(base); return 1; } @@ -755,12 +760,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, debug_activate(timer, expires); - cpu = smp_processor_id(); - -#if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP) - if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu)) - cpu = get_nohz_timer_target(); -#endif + cpu = get_nohz_timer_target(pinned); new_base = per_cpu(tvec_bases, cpu); if (base != new_base) { @@ -838,7 +838,7 @@ unsigned long apply_slack(struct timer_list *timer, unsigned long expires) bit = find_last_bit(&mask, BITS_PER_LONG); - mask = (1 << bit) - 1; + mask = (1UL << bit) - 1; expires_limit = expires_limit & ~(mask); @@ -949,14 +949,21 @@ void add_timer_on(struct timer_list *timer, int cpu) debug_activate(timer, timer->expires); internal_add_timer(base, timer); /* - * Check whether the other CPU is idle and needs to be - * triggered to reevaluate the timer wheel when nohz is - * active. We are protected against the other CPU fiddling + * Check whether the other CPU is in dynticks mode and needs + * to be triggered to reevaluate the timer wheel. + * We are protected against the other CPU fiddling * with the timer by holding the timer base lock. This also - * makes sure that a CPU on the way to idle can not evaluate - * the timer wheel. + * makes sure that a CPU on the way to stop its tick can not + * evaluate the timer wheel. + * + * Spare the IPI for deferrable timers on idle targets though. + * The next busy ticks will take care of it. Except full dynticks + * require special care against races with idle_cpu(), lets deal + * with that later. */ - wake_up_idle_cpu(cpu); + if (!tbase_get_deferrable(timer->base) || tick_nohz_full_cpu(cpu)) + wake_up_nohz_cpu(cpu); + spin_unlock_irqrestore(&base->lock, flags); } EXPORT_SYMBOL_GPL(add_timer_on); @@ -1029,14 +1036,14 @@ EXPORT_SYMBOL(try_to_del_timer_sync); * * Synchronization rules: Callers must prevent restarting of the timer, * otherwise this function is meaningless. It must not be called from - * interrupt contexts. The caller must not hold locks which would prevent - * completion of the timer's handler. The timer's handler must not call - * add_timer_on(). Upon exit the timer is not queued and the handler is - * not running on any CPU. + * interrupt contexts unless the timer is an irqsafe one. The caller must + * not hold locks which would prevent completion of the timer's + * handler. The timer's handler must not call add_timer_on(). Upon exit the + * timer is not queued and the handler is not running on any CPU. * - * Note: You must not hold locks that are held in interrupt context - * while calling this function. Even if the lock has nothing to do - * with the timer in question. Here's why: + * Note: For !irqsafe timers, you must not hold locks that are held in + * interrupt context while calling this function. Even if the lock has + * nothing to do with the timer in question. Here's why: * * CPU0 CPU1 * ---- ---- @@ -1073,7 +1080,7 @@ int del_timer_sync(struct timer_list *timer) * don't use it in hardirq context, because it * could lead to deadlock. */ - WARN_ON(in_irq()); + WARN_ON(in_irq() && !tbase_get_irqsafe(timer->base)); for (;;) { int ret = try_to_del_timer_sync(timer); if (ret >= 0) @@ -1108,7 +1115,7 @@ static int cascade(struct tvec_base *base, struct tvec *tv, int index) static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long), unsigned long data) { - int preempt_count = preempt_count(); + int count = preempt_count(); #ifdef CONFIG_LOCKDEP /* @@ -1135,16 +1142,16 @@ static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long), lock_map_release(&lockdep_map); - if (preempt_count != preempt_count()) { + if (count != preempt_count()) { WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n", - fn, preempt_count, preempt_count()); + fn, count, preempt_count()); /* * Restore the preempt count. That gives us a decent * chance to survive and extract information. If the * callback kept a lock held, bad luck, but not worse * than the BUG() we had. */ - preempt_count() = preempt_count; + preempt_count_set(count); } } @@ -1162,6 +1169,10 @@ static inline void __run_timers(struct tvec_base *base) struct timer_list *timer; spin_lock_irq(&base->lock); + if (catchup_timer_jiffies(base)) { + spin_unlock_irq(&base->lock); + return; + } while (time_after_eq(jiffies, base->timer_jiffies)) { struct list_head work_list; struct list_head *head = &work_list; @@ -1176,30 +1187,38 @@ static inline void __run_timers(struct tvec_base *base) !cascade(base, &base->tv4, INDEX(2))) cascade(base, &base->tv5, INDEX(3)); ++base->timer_jiffies; - list_replace_init(base->tv1.vec + index, &work_list); + list_replace_init(base->tv1.vec + index, head); while (!list_empty(head)) { void (*fn)(unsigned long); unsigned long data; + bool irqsafe; timer = list_first_entry(head, struct timer_list,entry); fn = timer->function; data = timer->data; + irqsafe = tbase_get_irqsafe(timer->base); timer_stats_account_timer(timer); base->running_timer = timer; detach_expired_timer(timer, base); - spin_unlock_irq(&base->lock); - call_timer_fn(timer, fn, data); - spin_lock_irq(&base->lock); + if (irqsafe) { + spin_unlock(&base->lock); + call_timer_fn(timer, fn, data); + spin_lock(&base->lock); + } else { + spin_unlock_irq(&base->lock); + call_timer_fn(timer, fn, data); + spin_lock_irq(&base->lock); + } } } base->running_timer = NULL; spin_unlock_irq(&base->lock); } -#ifdef CONFIG_NO_HZ +#ifdef CONFIG_NO_HZ_COMMON /* * Find out when the next timer event is due to happen. This * is used on S/390 to stop all activity when a CPU is idle. @@ -1363,7 +1382,6 @@ void update_process_times(int user_tick) account_process_tick(p, user_tick); run_local_timers(); rcu_check_callbacks(cpu, user_tick); - printk_tick(); #ifdef CONFIG_IRQ_WORK if (in_irq()) irq_work_run(); @@ -1407,61 +1425,6 @@ SYSCALL_DEFINE1(alarm, unsigned int, seconds) #endif -/** - * sys_getpid - return the thread group id of the current process - * - * Note, despite the name, this returns the tgid not the pid. The tgid and - * the pid are identical unless CLONE_THREAD was specified on clone() in - * which case the tgid is the same in all threads of the same group. - * - * This is SMP safe as current->tgid does not change. - */ -SYSCALL_DEFINE0(getpid) -{ - return task_tgid_vnr(current); -} - -/* - * Accessing ->real_parent is not SMP-safe, it could - * change from under us. However, we can use a stale - * value of ->real_parent under rcu_read_lock(), see - * release_task()->call_rcu(delayed_put_task_struct). - */ -SYSCALL_DEFINE0(getppid) -{ - int pid; - - rcu_read_lock(); - pid = task_tgid_vnr(rcu_dereference(current->real_parent)); - rcu_read_unlock(); - - return pid; -} - -SYSCALL_DEFINE0(getuid) -{ - /* Only we change this so SMP safe */ - return from_kuid_munged(current_user_ns(), current_uid()); -} - -SYSCALL_DEFINE0(geteuid) -{ - /* Only we change this so SMP safe */ - return from_kuid_munged(current_user_ns(), current_euid()); -} - -SYSCALL_DEFINE0(getgid) -{ - /* Only we change this so SMP safe */ - return from_kgid_munged(current_user_ns(), current_gid()); -} - -SYSCALL_DEFINE0(getegid) -{ - /* Only we change this so SMP safe */ - return from_kgid_munged(current_user_ns(), current_egid()); -} - static void process_timeout(unsigned long __data) { wake_up_process((struct task_struct *)__data); @@ -1569,96 +1532,11 @@ signed long __sched schedule_timeout_uninterruptible(signed long timeout) } EXPORT_SYMBOL(schedule_timeout_uninterruptible); -/* Thread ID - the internal kernel "pid" */ -SYSCALL_DEFINE0(gettid) -{ - return task_pid_vnr(current); -} - -/** - * do_sysinfo - fill in sysinfo struct - * @info: pointer to buffer to fill - */ -int do_sysinfo(struct sysinfo *info) -{ - unsigned long mem_total, sav_total; - unsigned int mem_unit, bitcount; - struct timespec tp; - - memset(info, 0, sizeof(struct sysinfo)); - - ktime_get_ts(&tp); - monotonic_to_bootbased(&tp); - info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0); - - get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT); - - info->procs = nr_threads; - - si_meminfo(info); - si_swapinfo(info); - - /* - * If the sum of all the available memory (i.e. ram + swap) - * is less than can be stored in a 32 bit unsigned long then - * we can be binary compatible with 2.2.x kernels. If not, - * well, in that case 2.2.x was broken anyways... - * - * -Erik Andersen <andersee@debian.org> - */ - - mem_total = info->totalram + info->totalswap; - if (mem_total < info->totalram || mem_total < info->totalswap) - goto out; - bitcount = 0; - mem_unit = info->mem_unit; - while (mem_unit > 1) { - bitcount++; - mem_unit >>= 1; - sav_total = mem_total; - mem_total <<= 1; - if (mem_total < sav_total) - goto out; - } - - /* - * If mem_total did not overflow, multiply all memory values by - * info->mem_unit and set it to 1. This leaves things compatible - * with 2.2.x, and also retains compatibility with earlier 2.4.x - * kernels... - */ - - info->mem_unit = 1; - info->totalram <<= bitcount; - info->freeram <<= bitcount; - info->sharedram <<= bitcount; - info->bufferram <<= bitcount; - info->totalswap <<= bitcount; - info->freeswap <<= bitcount; - info->totalhigh <<= bitcount; - info->freehigh <<= bitcount; - -out: - return 0; -} - -SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info) -{ - struct sysinfo val; - - do_sysinfo(&val); - - if (copy_to_user(info, &val, sizeof(struct sysinfo))) - return -EFAULT; - - return 0; -} - -static int __cpuinit init_timers_cpu(int cpu) +static int init_timers_cpu(int cpu) { int j; struct tvec_base *base; - static char __cpuinitdata tvec_base_done[NR_CPUS]; + static char tvec_base_done[NR_CPUS]; if (!tvec_base_done[cpu]) { static char boot_done; @@ -1667,15 +1545,13 @@ static int __cpuinit init_timers_cpu(int cpu) /* * The APs use this path later in boot */ - base = kmalloc_node(sizeof(*base), - GFP_KERNEL | __GFP_ZERO, - cpu_to_node(cpu)); + base = kzalloc_node(sizeof(*base), GFP_KERNEL, + cpu_to_node(cpu)); if (!base) return -ENOMEM; - /* Make sure that tvec_base is 2 byte aligned */ - if (tbase_get_deferrable(base)) { - WARN_ON(1); + /* Make sure tvec_base has TIMER_FLAG_MASK bits free */ + if (WARN_ON(base != tbase_get_base(base))) { kfree(base); return -ENOMEM; } @@ -1690,12 +1566,12 @@ static int __cpuinit init_timers_cpu(int cpu) boot_done = 1; base = &boot_tvec_bases; } + spin_lock_init(&base->lock); tvec_base_done[cpu] = 1; } else { base = per_cpu(tvec_bases, cpu); } - spin_lock_init(&base->lock); for (j = 0; j < TVN_SIZE; j++) { INIT_LIST_HEAD(base->tv5.vec + j); @@ -1709,6 +1585,7 @@ static int __cpuinit init_timers_cpu(int cpu) base->timer_jiffies = jiffies; base->next_timer = base->timer_jiffies; base->active_timers = 0; + base->all_timers = 0; return 0; } @@ -1726,7 +1603,7 @@ static void migrate_timer_list(struct tvec_base *new_base, struct list_head *hea } } -static void __cpuinit migrate_timers(int cpu) +static void migrate_timers(int cpu) { struct tvec_base *old_base; struct tvec_base *new_base; @@ -1759,7 +1636,7 @@ static void __cpuinit migrate_timers(int cpu) } #endif /* CONFIG_HOTPLUG_CPU */ -static int __cpuinit timer_cpu_notify(struct notifier_block *self, +static int timer_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { long cpu = (long)hcpu; @@ -1784,19 +1661,23 @@ static int __cpuinit timer_cpu_notify(struct notifier_block *self, return NOTIFY_OK; } -static struct notifier_block __cpuinitdata timers_nb = { +static struct notifier_block timers_nb = { .notifier_call = timer_cpu_notify, }; void __init init_timers(void) { - int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE, - (void *)(long)smp_processor_id()); + int err; - init_timer_stats(); + /* ensure there are enough low bits for flags in timer->base pointer */ + BUILD_BUG_ON(__alignof__(struct tvec_base) & TIMER_FLAG_MASK); + err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE, + (void *)(long)smp_processor_id()); BUG_ON(err != NOTIFY_OK); + + init_timer_stats(); register_cpu_notifier(&timers_nb); open_softirq(TIMER_SOFTIRQ, run_timer_softirq); } |
