Re: [PATCH v3 2/4] perf: Enqueue SIGTRAP always via task_work.

[Frederic Weisbecker]

Le Wed, Apr 10, 2024 at 03:47:02PM +0200, Sebastian Andrzej Siewior a écrit :
> On 2024-04-10 13:37:05 [+0200], Frederic Weisbecker wrote:
> > > Couldn't we either flush _or_ remove the task_work in perf_release()?
> > 
> > Right so the problem in perf_release() is that we may be dealing with task works
> > of other tasks than current. In that case, task_work_cancel() is fine if it
> > successes. But if it fails, you don't have the guarantee that the task work
> > isn't concurrently running or about to run. And you have no way to know about
> > that. So then you need some sort of flushing indeed.
> 
> Since perf_release() preemptible, a wait/sleep for completion would be
> best (instead of flushing).

Like this then?

https://lore.kernel.org/all/202403310406.TPrIela8-lkp@xxxxxxxxx/T/#m63c28147d8ac06b21c64d7784d49f892e06c0e50

> > Thanks.
> > 
> > > > Thanks.
> 
> Sebastian