Re: [PATCH v3 06/11] perf: Add support for SIGTRAP on perf events

[Marco Elver]

On Wed, 31 Mar 2021 at 16:51, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Wed, Mar 31, 2021 at 02:32:58PM +0200, Marco Elver wrote:
> > On Mon, 29 Mar 2021 at 14:07, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> >
> > > (and we might already have a problem on some architectures where there
> > > can be significant time between these due to not having
> > > arch_irq_work_raise(), so ideally we ought to double check current in
> > > your case)
> >
> > I missed this bit -- just to verify: here we want to check that
> > event->ctx->task == current, in case the the irq_work runs when the
> > current task has already been replaced. Correct?
>
> Yeah, just not sure what a decent failure would be, silent ignore seems
> undesired, maybe WARN and archs that can trigger it get to fix it ?

I'll go with a WARN and add a comment.

This also revealed there should be a requirement that sigtrap events
must be associated with a task (syzkaller managed to trigger the
warning for cpu events).

Thanks,
-- Marco