Messages in this thread | | | Date | Tue, 9 Apr 2024 12:35:46 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH v3 3/4] perf: Remove perf_swevent_get_recursion_context() from perf_pending_task(). |
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Le Tue, Apr 09, 2024 at 08:25:01AM +0200, Sebastian Andrzej Siewior a écrit : > On 2024-04-09 00:06:00 [+0200], Frederic Weisbecker wrote: > > > diff --git a/kernel/events/core.c b/kernel/events/core.c > > > index e0b2da8de485f..5400f7ed2f98b 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(); > > > > Well, if a software event happens during perf_sigtrap(), the task work > > may be requeued endlessly and the task may get stuck in task_work_run()... > > The last time I checked it had no users in the task context. How would > that happen?
I guess many tracepoint events would do the trick. Such as trace_lock_acquire() for example.
Thanks.
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