diff options
| -rw-r--r-- | kernel/time/timer.c | 51 |
1 files changed, 35 insertions, 16 deletions
diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 8d7c23e55c85..8f29abeb8c4d 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -960,28 +960,36 @@ static inline int __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only) { struct timer_base *base, *new_base; - unsigned long flags; + unsigned int idx = UINT_MAX; + unsigned long clk = 0, flags; int ret = 0; /* - * TODO: Calculate the array bucket of the timer right here w/o - * holding the base lock. This allows to check not only - * timer->expires == expires below, but also whether the timer - * ends up in the same bucket. If we really need to requeue - * the timer then we check whether base->clk have - * advanced between here and locking the timer base. If - * jiffies advanced we have to recalc the array bucket with the - * lock held. - */ - - /* - * This is a common optimization triggered by the - * networking code - if the timer is re-modified - * to be the same thing then just return: + * This is a common optimization triggered by the networking code - if + * the timer is re-modified to have the same timeout or ends up in the + * same array bucket then just return: */ if (timer_pending(timer)) { if (timer->expires == expires) return 1; + /* + * Take the current timer_jiffies of base, but without holding + * the lock! + */ + base = get_timer_base(timer->flags); + clk = base->clk; + + idx = calc_wheel_index(expires, clk); + + /* + * Retrieve and compare the array index of the pending + * timer. If it matches set the expiry to the new value so a + * subsequent call will exit in the expires check above. + */ + if (idx == timer_get_idx(timer)) { + timer->expires = expires; + return 1; + } } timer_stats_timer_set_start_info(timer); @@ -1018,7 +1026,18 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only) } timer->expires = expires; - internal_add_timer(base, timer); + /* + * If 'idx' was calculated above and the base time did not advance + * between calculating 'idx' and taking the lock, only enqueue_timer() + * and trigger_dyntick_cpu() is required. Otherwise we need to + * (re)calculate the wheel index via internal_add_timer(). + */ + if (idx != UINT_MAX && clk == base->clk) { + enqueue_timer(base, timer, idx); + trigger_dyntick_cpu(base, timer); + } else { + internal_add_timer(base, timer); + } out_unlock: spin_unlock_irqrestore(&base->lock, flags); |