diff options
| -rw-r--r-- | kernel/time/timer.c | 57 |
1 files changed, 52 insertions, 5 deletions
diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 2b5e8c26b697..e4fcf5643b6f 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1017,7 +1017,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, unsigned int option unsigned int idx = UINT_MAX; int ret = 0; - BUG_ON(!timer->function); + debug_assert_init(timer); /* * This is a common optimization triggered by the networking code - if @@ -1044,6 +1044,14 @@ __mod_timer(struct timer_list *timer, unsigned long expires, unsigned int option * dequeue/enqueue dance. */ base = lock_timer_base(timer, &flags); + /* + * Has @timer been shutdown? This needs to be evaluated + * while holding base lock to prevent a race against the + * shutdown code. + */ + if (!timer->function) + goto out_unlock; + forward_timer_base(base); if (timer_pending(timer) && (options & MOD_TIMER_REDUCE) && @@ -1070,6 +1078,14 @@ __mod_timer(struct timer_list *timer, unsigned long expires, unsigned int option } } else { base = lock_timer_base(timer, &flags); + /* + * Has @timer been shutdown? This needs to be evaluated + * while holding base lock to prevent a race against the + * shutdown code. + */ + if (!timer->function) + goto out_unlock; + forward_timer_base(base); } @@ -1128,8 +1144,12 @@ out_unlock: * mod_timer_pending() is the same for pending timers as mod_timer(), but * will not activate inactive timers. * + * If @timer->function == NULL then the start operation is silently + * discarded. + * * Return: - * * %0 - The timer was inactive and not modified + * * %0 - The timer was inactive and not modified or was in + * shutdown state and the operation was discarded * * %1 - The timer was active and requeued to expire at @expires */ int mod_timer_pending(struct timer_list *timer, unsigned long expires) @@ -1155,8 +1175,12 @@ EXPORT_SYMBOL(mod_timer_pending); * same timer, then mod_timer() is the only safe way to modify the timeout, * since add_timer() cannot modify an already running timer. * + * If @timer->function == NULL then the start operation is silently + * discarded. In this case the return value is 0 and meaningless. + * * Return: - * * %0 - The timer was inactive and started + * * %0 - The timer was inactive and started or was in shutdown + * state and the operation was discarded * * %1 - The timer was active and requeued to expire at @expires or * the timer was active and not modified because @expires did * not change the effective expiry time @@ -1176,8 +1200,12 @@ EXPORT_SYMBOL(mod_timer); * modify an enqueued timer if that would reduce the expiration time. If * @timer is not enqueued it starts the timer. * + * If @timer->function == NULL then the start operation is silently + * discarded. + * * Return: - * * %0 - The timer was inactive and started + * * %0 - The timer was inactive and started or was in shutdown + * state and the operation was discarded * * %1 - The timer was active and requeued to expire at @expires or * the timer was active and not modified because @expires * did not change the effective expiry time such that the @@ -1200,6 +1228,9 @@ EXPORT_SYMBOL(timer_reduce); * The @timer->expires and @timer->function fields must be set prior * to calling this function. * + * If @timer->function == NULL then the start operation is silently + * discarded. + * * If @timer->expires is already in the past @timer will be queued to * expire at the next timer tick. * @@ -1228,7 +1259,9 @@ void add_timer_on(struct timer_list *timer, int cpu) struct timer_base *new_base, *base; unsigned long flags; - if (WARN_ON_ONCE(timer_pending(timer) || !timer->function)) + debug_assert_init(timer); + + if (WARN_ON_ONCE(timer_pending(timer))) return; new_base = get_timer_cpu_base(timer->flags, cpu); @@ -1239,6 +1272,13 @@ void add_timer_on(struct timer_list *timer, int cpu) * wrong base locked. See lock_timer_base(). */ base = lock_timer_base(timer, &flags); + /* + * Has @timer been shutdown? This needs to be evaluated while + * holding base lock to prevent a race against the shutdown code. + */ + if (!timer->function) + goto out_unlock; + if (base != new_base) { timer->flags |= TIMER_MIGRATING; @@ -1252,6 +1292,7 @@ void add_timer_on(struct timer_list *timer, int cpu) debug_timer_activate(timer); internal_add_timer(base, timer); +out_unlock: raw_spin_unlock_irqrestore(&base->lock, flags); } EXPORT_SYMBOL_GPL(add_timer_on); @@ -1541,6 +1582,12 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head) fn = timer->function; + if (WARN_ON_ONCE(!fn)) { + /* Should never happen. Emphasis on should! */ + base->running_timer = NULL; + continue; + } + if (timer->flags & TIMER_IRQSAFE) { raw_spin_unlock(&base->lock); call_timer_fn(timer, fn, baseclk); |