Re: [PATCH 2/4] perf: Fix irq work dereferencing garbage

[Frederic Weisbecker]

Le Fri, May 02, 2025 at 01:30:02PM +0200, Peter Zijlstra a écrit :
> On Fri, May 02, 2025 at 12:29:18PM +0200, Peter Zijlstra wrote:
> 
> > > @@ -13951,18 +13943,25 @@ perf_event_exit_event(struct perf_event *event,
> > >  	/*
> > >  	 * Child events can be freed.
> > >  	 */
> > > -	if (is_child) {
> > > -		if (parent_event) {
> > > -			mutex_unlock(&parent_event->child_mutex);
> > > -			/*
> > > -			 * Kick perf_poll() for is_event_hup();
> > > -			 */
> > > -			perf_event_wakeup(parent_event);
> > > +	if (parent_event) {
> > > +		mutex_unlock(&parent_event->child_mutex);
> > > +		/*
> > > +		 * Kick perf_poll() for is_event_hup();
> > > +		 */
> > > +		perf_event_wakeup(parent_event);
> > 
> > Should not this perf_event_wakeup() be inside the next if() as well?
> > doing anything on parent_event when !ATTACH_CHILD seems dodgy.
> 
> I made this change, and munged the original changelog on top and stuffed
> the patches into queue/perf/core.

Looks good, but it looks like you trimmed the changelog with the
race windows part. Though I must confess, who wants to read that anyway? ;-)

-- 
Frederic Weisbecker
SUSE Labs