Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 9 Apr 2024 15:47:29 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH v3 2/4] perf: Enqueue SIGTRAP always via task_work. |
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On 2024-04-09 14:36:51 [+0200], Frederic Weisbecker wrote: > > That wake_up() within preempt_disable() section breaks on RT. > > Ah, but the wake-up still wants to go inside recursion protection somehow or > it could generate task_work loop again due to tracepoint events...
okay.
> Although... the wake up occurs only when the event is dead after all...
corner case or not, it has to work, right?
> > How do we go on from here? > > I'd tend to think you need my patchset first because the problems it > fixes were not easily visible as long as there was an irq work to take > care of things most of the time. But once you rely on task_work only then > these become a real problem. Especially the sync against perf_release().
I don't mind rebasing on top of your series. But defaulting to task_work is not an option then?
RT wise the irq_work is not handled in hardirq because of locks it acquires and is handled instead in a thread. Depending on the priority the task (receiving the event) it may run before the irq_work-thread. Therefore the task_work looked neat because the event would be handled _before_ the task returned to userland.
Couldn't we either flush _or_ remove the task_work in perf_release()?
> Thanks. Sebastian
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