From 2d44ae4d7135b9aee26439b3523b43473381bc5f Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 25 Jan 2008 21:08:31 +0100 Subject: hrtimer: clean up cpu->base locking tricks In order to more easily allow for the scheduler to use timers, clean up the locking a bit. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/hrtimer.c | 20 +++++++++++++++++++- kernel/time/tick-sched.c | 8 -------- 2 files changed, 19 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index f994bb8065e6..9f850ca032b6 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1063,7 +1063,9 @@ void hrtimer_interrupt(struct clock_event_device *dev) basenow = ktime_add(now, base->offset); while ((node = base->first)) { + enum hrtimer_restart (*fn)(struct hrtimer *); struct hrtimer *timer; + int restart; timer = rb_entry(node, struct hrtimer, node); @@ -1091,13 +1093,29 @@ void hrtimer_interrupt(struct clock_event_device *dev) HRTIMER_STATE_CALLBACK, 0); timer_stats_account_hrtimer(timer); + fn = timer->function; + if (timer->cb_mode == HRTIMER_CB_IRQSAFE_NO_SOFTIRQ) { + /* + * Used for scheduler timers, avoid lock + * inversion with rq->lock and tasklist_lock. + * + * These timers are required to deal with + * enqueue expiry themselves and are not + * allowed to migrate. + */ + spin_unlock(&cpu_base->lock); + restart = fn(timer); + spin_lock(&cpu_base->lock); + } else + restart = fn(timer); + /* * Note: We clear the CALLBACK bit after * enqueue_hrtimer to avoid reprogramming of * the event hardware. This happens at the end * of this function anyway. */ - if (timer->function(timer) != HRTIMER_NORESTART) { + if (restart != HRTIMER_NORESTART) { BUG_ON(timer->state != HRTIMER_STATE_CALLBACK); enqueue_hrtimer(timer, base, 0); } diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 5f9fb645b725..1a21b6fdb674 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -514,7 +514,6 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) { struct tick_sched *ts = container_of(timer, struct tick_sched, sched_timer); - struct hrtimer_cpu_base *base = timer->base->cpu_base; struct pt_regs *regs = get_irq_regs(); ktime_t now = ktime_get(); int cpu = smp_processor_id(); @@ -552,15 +551,8 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) touch_softlockup_watchdog(); ts->idle_jiffies++; } - /* - * update_process_times() might take tasklist_lock, hence - * drop the base lock. sched-tick hrtimers are per-CPU and - * never accessible by userspace APIs, so this is safe to do. - */ - spin_unlock(&base->lock); update_process_times(user_mode(regs)); profile_tick(CPU_PROFILING); - spin_lock(&base->lock); } /* Do not restart, when we are in the idle loop */ -- cgit v1.2.3-59-g8ed1b