Re: [PATCH v2] perf: Synchronously cleanup child events

From: Alexei Starovoitov
Date: Fri Jan 22 2016 - 14:44:12 EST


On Fri, Jan 22, 2016 at 01:38:47PM +0100, Peter Zijlstra wrote:
> On Fri, Jan 22, 2016 at 01:35:40PM +0200, Alexander Shishkin wrote:
> > Peter Zijlstra <peterz@xxxxxxxxxxxxx> writes:
> >
> > > So I think there's a number of problems still :-(

I've been looking at how perf_event->owner is handled and couldn't
figure out how you deal with the case of passing perf_event_fd via scm_rights.
It seems one process can open an event, pass it to another process,
but when current process exists owner will still point to dead task,
since refcount > 0.
Which part am I missing?