On Tue, Oct 06, 2015 at 09:29:37AM -0700, Paul E. McKenney wrote:
> void rcu_sched_qs(void)
> {
> + unsigned long flags;
> +
> if (__this_cpu_read(rcu_sched_data.cpu_no_qs.s)) {
> trace_rcu_grace_period(TPS("rcu_sched"),
> __this_cpu_read(rcu_sched_data.gpnum),
> TPS("cpuqs"));
> __this_cpu_write(rcu_sched_data.cpu_no_qs.b.norm, false);
> + if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp))
> + return;
> + local_irq_save(flags);
> if (__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp)) {
> __this_cpu_write(rcu_sched_data.cpu_no_qs.b.exp, false);
> rcu_report_exp_rdp(&rcu_sched_state,
> this_cpu_ptr(&rcu_sched_data),
> true);
> }
> + local_irq_restore(flags);
> }
> }
*sigh*.. still rare I suppose, but should we look at doing something
like this?
---
kernel/sched/core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fe819298c220..3d830c3491c4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3050,7 +3050,6 @@ static void __sched __schedule(void)
cpu = smp_processor_id();
rq = cpu_rq(cpu);
- rcu_note_context_switch();
prev = rq->curr;
schedule_debug(prev);
@@ -3058,13 +3057,16 @@ static void __sched __schedule(void)
if (sched_feat(HRTICK))
hrtick_clear(rq);
+ local_irq_disable();
+ rcu_note_context_switch();
+
/*
* Make sure that signal_pending_state()->signal_pending() below
* can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
* done by the caller to avoid the race with signal_wake_up().
*/
smp_mb__before_spinlock();
- raw_spin_lock_irq(&rq->lock);
+ raw_spin_lock(&rq->lock);
lockdep_pin_lock(&rq->lock);
rq->clock_skip_update <<= 1; /* promote REQ to ACT */
--
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