Messages in this thread Patch in this message | | | From | Sebastian Andrzej Siewior <> | Subject | [PATCH v2 3/4] perf: Remove perf_swevent_get_recursion_context() from perf_pending_task(). | Date | Tue, 12 Mar 2024 19:01:51 +0100 |
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perf_swevent_get_recursion_context() is supposed to avoid recursion. This requires to remain on the same CPU in order to decrement/ increment the same counter. This is done by using preempt_disable(). Having preemption disabled while sending a signal leads to locking problems on PREEMPT_RT because sighand, a spinlock_t, becomes a sleeping lock.
This callback runs in task context and currently delivers only a signal to "itself". Any kind of recusrion protection in this context is not required.
Remove recursion protection in perf_pending_task().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- kernel/events/core.c | 12 ------------ 1 file changed, 12 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index e9926baaa1587..806514d76d8dc 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6785,14 +6785,6 @@ static void perf_pending_irq(struct irq_work *entry) static void perf_pending_task(struct callback_head *head) { struct perf_event *event = container_of(head, struct perf_event, pending_task); - int rctx; - - /* - * If we 'fail' here, that's OK, it means recursion is already disabled - * and we won't recurse 'further'. - */ - preempt_disable_notrace(); - rctx = perf_swevent_get_recursion_context(); if (event->pending_work) { event->pending_work = 0; @@ -6800,10 +6792,6 @@ static void perf_pending_task(struct callback_head *head) local_dec(&event->ctx->nr_pending); } - if (rctx >= 0) - perf_swevent_put_recursion_context(rctx); - preempt_enable_notrace(); - put_event(event); } -- 2.43.0
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