From: Peter Zijlstra <peterz@infradead.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, vince@deater.net,
eranian@google.com, Arnaldo Carvalho de Melo <acme@infradead.org>,
Jiri Olsa <jolsa@kernel.org>
Subject: Re: [PATCH v2] perf: Synchronously cleanup child events
Date: Mon, 25 Jan 2016 12:48:46 +0100 [thread overview]
Message-ID: <20160125114846.GW6357@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160122194403.GC11338@ast-mbp.thefacebook.com>
On Fri, Jan 22, 2016 at 11:44:03AM -0800, Alexei Starovoitov wrote:
> 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@infradead.org> 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?
Nothing, you raised a good point. I think this shows we cannot link
!event->owner to an event being 'dead'.
If we keep these two states separate, the scm_rights thing should work
again.
next prev parent reply other threads:[~2016-01-25 11:48 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-15 11:22 [PATCH] perf: Cleanup user's child events Alexander Shishkin
2016-01-15 12:54 ` Peter Zijlstra
2016-01-15 13:05 ` Alexander Shishkin
2016-01-15 13:09 ` Peter Zijlstra
2016-01-15 14:07 ` [PATCH] perf: Synchronously cleanup " Alexander Shishkin
2016-01-15 17:57 ` Peter Zijlstra
2016-01-18 12:07 ` Alexander Shishkin
2016-01-18 12:37 ` Alexander Shishkin
2016-01-18 14:44 ` Peter Zijlstra
2016-01-19 15:12 ` [PATCH v2] " Alexander Shishkin
2016-01-19 20:05 ` Peter Zijlstra
2016-01-19 21:58 ` Alexei Starovoitov
2016-01-20 8:32 ` Peter Zijlstra
2016-01-21 4:55 ` Alexei Starovoitov
2016-01-20 7:04 ` Alexander Shishkin
2016-01-20 8:03 ` Peter Zijlstra
2016-01-22 11:35 ` Alexander Shishkin
2016-01-22 12:12 ` Peter Zijlstra
2016-01-22 12:38 ` Peter Zijlstra
2016-01-22 19:44 ` Alexei Starovoitov
2016-01-25 11:48 ` Peter Zijlstra [this message]
2016-01-25 14:54 ` Peter Zijlstra
2016-01-25 21:04 ` Peter Zijlstra
2016-01-26 4:59 ` Alexei Starovoitov
2016-01-26 16:16 ` Peter Zijlstra
2016-01-26 17:24 ` Peter Zijlstra
2016-01-26 23:31 ` Alexei Starovoitov
2016-01-27 9:58 ` Peter Zijlstra
2016-01-27 17:52 ` Alexei Starovoitov
2016-01-29 11:28 ` [tip:perf/urgent] perf/bpf: Convert perf_event_array to use struct file tip-bot for Alexei Starovoitov
2016-01-29 20:01 ` Alexei Starovoitov
2016-01-19 20:07 ` [PATCH v2] perf: Synchronously cleanup child events Peter Zijlstra
2016-01-19 7:45 ` [PATCH] " Ingo Molnar
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