diff options
Diffstat (limited to 'kernel/time/timer.c')
-rw-r--r-- | kernel/time/timer.c | 100 |
1 files changed, 77 insertions, 23 deletions
diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 7d63b7347066..4a243860097a 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -43,6 +43,7 @@ #include <linux/sched/debug.h> #include <linux/slab.h> #include <linux/compat.h> +#include <linux/random.h> #include <linux/uaccess.h> #include <asm/unistd.h> @@ -196,6 +197,7 @@ EXPORT_SYMBOL(jiffies_64); struct timer_base { raw_spinlock_t lock; struct timer_list *running_timer; + spinlock_t expiry_lock; unsigned long clk; unsigned long next_expiry; unsigned int cpu; @@ -518,8 +520,8 @@ static int calc_wheel_index(unsigned long expires, unsigned long clk) * Force expire obscene large timeouts to expire at the * capacity limit of the wheel. */ - if (expires >= WHEEL_TIMEOUT_CUTOFF) - expires = WHEEL_TIMEOUT_MAX; + if (delta >= WHEEL_TIMEOUT_CUTOFF) + expires = clk + WHEEL_TIMEOUT_MAX; idx = calc_index(expires, LVL_DEPTH - 1); } @@ -581,7 +583,15 @@ trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer) * Set the next expiry time and kick the CPU so it can reevaluate the * wheel: */ - base->next_expiry = timer->expires; + if (time_before(timer->expires, base->clk)) { + /* + * Prevent from forward_timer_base() moving the base->clk + * backward + */ + base->next_expiry = base->clk; + } else { + base->next_expiry = timer->expires; + } wake_up_nohz_cpu(base->cpu); } @@ -893,10 +903,13 @@ static inline void forward_timer_base(struct timer_base *base) * If the next expiry value is > jiffies, then we fast forward to * jiffies otherwise we forward to the next expiry value. */ - if (time_after(base->next_expiry, jnow)) + if (time_after(base->next_expiry, jnow)) { base->clk = jnow; - else + } else { + if (WARN_ON_ONCE(time_before(base->next_expiry, base->clk))) + return; base->clk = base->next_expiry; + } #endif } @@ -1201,14 +1214,8 @@ int del_timer(struct timer_list *timer) } EXPORT_SYMBOL(del_timer); -/** - * try_to_del_timer_sync - Try to deactivate a timer - * @timer: timer to delete - * - * This function tries to deactivate a timer. Upon successful (ret >= 0) - * exit the timer is not queued and the handler is not running on any CPU. - */ -int try_to_del_timer_sync(struct timer_list *timer) +static int __try_to_del_timer_sync(struct timer_list *timer, + struct timer_base **basep) { struct timer_base *base; unsigned long flags; @@ -1216,7 +1223,7 @@ int try_to_del_timer_sync(struct timer_list *timer) debug_assert_init(timer); - base = lock_timer_base(timer, &flags); + *basep = base = lock_timer_base(timer, &flags); if (base->running_timer != timer) ret = detach_if_pending(timer, base, true); @@ -1225,9 +1232,42 @@ int try_to_del_timer_sync(struct timer_list *timer) return ret; } + +/** + * try_to_del_timer_sync - Try to deactivate a timer + * @timer: timer to delete + * + * This function tries to deactivate a timer. Upon successful (ret >= 0) + * exit the timer is not queued and the handler is not running on any CPU. + */ +int try_to_del_timer_sync(struct timer_list *timer) +{ + struct timer_base *base; + + return __try_to_del_timer_sync(timer, &base); +} EXPORT_SYMBOL(try_to_del_timer_sync); -#ifdef CONFIG_SMP +#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT_FULL) +static int __del_timer_sync(struct timer_list *timer) +{ + struct timer_base *base; + int ret; + + for (;;) { + ret = __try_to_del_timer_sync(timer, &base); + if (ret >= 0) + return ret; + + /* + * When accessing the lock, timers of base are no longer expired + * and so timer is no longer running. + */ + spin_lock(&base->expiry_lock); + spin_unlock(&base->expiry_lock); + } +} + /** * del_timer_sync - deactivate a timer and wait for the handler to finish. * @timer: the timer to be deactivated @@ -1283,12 +1323,8 @@ int del_timer_sync(struct timer_list *timer) * could lead to deadlock. */ WARN_ON(in_irq() && !(timer->flags & TIMER_IRQSAFE)); - for (;;) { - int ret = try_to_del_timer_sync(timer); - if (ret >= 0) - return ret; - cpu_relax(); - } + + return __del_timer_sync(timer); } EXPORT_SYMBOL(del_timer_sync); #endif @@ -1357,13 +1393,20 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head) fn = timer->function; - if (timer->flags & TIMER_IRQSAFE) { + if (!IS_ENABLED(CONFIG_PREEMPT_RT_FULL) && + timer->flags & TIMER_IRQSAFE) { raw_spin_unlock(&base->lock); call_timer_fn(timer, fn, baseclk); + base->running_timer = NULL; + spin_unlock(&base->expiry_lock); + spin_lock(&base->expiry_lock); raw_spin_lock(&base->lock); } else { raw_spin_unlock_irq(&base->lock); call_timer_fn(timer, fn, baseclk); + base->running_timer = NULL; + spin_unlock(&base->expiry_lock); + spin_lock(&base->expiry_lock); raw_spin_lock_irq(&base->lock); } } @@ -1646,6 +1689,13 @@ void update_process_times(int user_tick) scheduler_tick(); if (IS_ENABLED(CONFIG_POSIX_TIMERS)) run_posix_cpu_timers(p); + + /* The current CPU might make use of net randoms without receiving IRQs + * to renew them often enough. Let's update the net_rand_state from a + * non-constant value that's not affine to the number of calls to make + * sure it's updated when there's some activity (we don't care in idle). + */ + this_cpu_add(net_rand_state.s1, rol32(jiffies, 24) + user_tick); } /** @@ -1660,6 +1710,7 @@ static inline void __run_timers(struct timer_base *base) if (!time_after_eq(jiffies, base->clk)) return; + spin_lock(&base->expiry_lock); raw_spin_lock_irq(&base->lock); /* @@ -1686,8 +1737,8 @@ static inline void __run_timers(struct timer_base *base) while (levels--) expire_timers(base, heads + levels); } - base->running_timer = NULL; raw_spin_unlock_irq(&base->lock); + spin_unlock(&base->expiry_lock); } /* @@ -1697,6 +1748,8 @@ static __latent_entropy void run_timer_softirq(struct softirq_action *h) { struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); + irq_work_tick_soft(); + __run_timers(base); if (IS_ENABLED(CONFIG_NO_HZ_COMMON)) __run_timers(this_cpu_ptr(&timer_bases[BASE_DEF])); @@ -1932,6 +1985,7 @@ static void __init init_timer_cpu(int cpu) base->cpu = cpu; raw_spin_lock_init(&base->lock); base->clk = jiffies; + spin_lock_init(&base->expiry_lock); } } |