diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2013-11-20 12:22:37 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-01-13 17:38:55 +0100 |
| commit | 8cb75e0c4ec9786b81439761eac1d18d4a931af3 (patch) | |
| tree | 9d13e6c3580a36cd76d1b3a96827795949519409 /kernel | |
| parent | c9c8986847d2f4fc474c10ee08afa57e7474096d (diff) | |
sched/preempt: Fix up missed PREEMPT_NEED_RESCHED folding
With various drivers wanting to inject idle time; we get people
calling idle routines outside of the idle loop proper.
Therefore we need to be extra careful about not missing
TIF_NEED_RESCHED -> PREEMPT_NEED_RESCHED propagations.
While looking at this, I also realized there's a small window in the
existing idle loop where we can miss TIF_NEED_RESCHED; when it hits
right after the tif_need_resched() test at the end of the loop but
right before the need_resched() test at the start of the loop.
So move preempt_fold_need_resched() out of the loop where we're
guaranteed to have TIF_NEED_RESCHED set.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-x9jgh45oeayzajz2mjt0y7d6@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cpu/idle.c | 17 | ||||
| -rw-r--r-- | kernel/sched/core.c | 3 |
2 files changed, 11 insertions, 9 deletions
diff --git a/kernel/cpu/idle.c b/kernel/cpu/idle.c index 988573a9a38..277f494c2a9 100644 --- a/kernel/cpu/idle.c +++ b/kernel/cpu/idle.c @@ -105,14 +105,17 @@ static void cpu_idle_loop(void) __current_set_polling(); } arch_cpu_idle_exit(); - /* - * We need to test and propagate the TIF_NEED_RESCHED - * bit here because we might not have send the - * reschedule IPI to idle tasks. - */ - if (tif_need_resched()) - set_preempt_need_resched(); } + + /* + * Since we fell out of the loop above, we know + * TIF_NEED_RESCHED must be set, propagate it into + * PREEMPT_NEED_RESCHED. + * + * This is required because for polling idle loops we will + * not have had an IPI to fold the state for us. + */ + preempt_set_need_resched(); tick_nohz_idle_exit(); schedule_preempt_disabled(); } diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 392c6f87906..0326c06953e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1510,8 +1510,7 @@ void scheduler_ipi(void) * TIF_NEED_RESCHED remotely (for the first time) will also send * this IPI. */ - if (tif_need_resched()) - set_preempt_need_resched(); + preempt_fold_need_resched(); if (llist_empty(&this_rq()->wake_list) && !tick_nohz_full_cpu(smp_processor_id()) |