On Wed, Nov 20, 2013 at 01:33:33AM +0100, Nicholas Mc Guire wrote:
> From a7259c360b6c8b873f5fcf6d5eed0ae78534a6c5 Mon Sep 17 00:00:00 2001
> From: Nicholas Mc Guire <der.herr@xxxxxxx>
> Date: Wed, 20 Nov 2013 07:22:09 +0800
> Subject: [PATCH] allow preemption in recursive migrate_disable call
>
> Minor cleanup in migrate_disable/migrate_enable. The recursive case
> does not need to disable preemption as it is "pinned" to the current
> cpu any way so it is safe to preempt it.
>
> No functional change to migrate_disable/enable
>
> Signed-off-by: Nicholas Mc Guire <der.herr@xxxxxxx>
> ---
> kernel/sched/core.c | 6 ++----
> 1 files changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index a7fafc28..22fa2e2 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -2418,13 +2418,12 @@ void migrate_disable(void)
> }
> #endif
>
> - preempt_disable();
> if (p->migrate_disable) {
> p->migrate_disable++;
> - preempt_enable();
> return;
> }
>
> + preempt_disable();
> preempt_lazy_disable();
> pin_current_cpu();
> p->migrate_disable = 1;
> @@ -2454,13 +2453,12 @@ void migrate_enable(void)
> #endif
> WARN_ON_ONCE(p->migrate_disable <= 0);
>
> - preempt_disable();
> if (migrate_disable_count(p) > 1) {
> p->migrate_disable--;
> - preempt_enable();
> return;
> }
>
> + preempt_disable();
> if (unlikely(migrate_disabled_updated(p))) {
> /*
> * Undo whatever update_migrate_disable() did, also see there
Is there a reason one uses p->migrate_disable and the other uses
migrate_disable_count(p) ?
Other than that,
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
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