From: Peter Zijlstra <peterz@infradead.org>
To: James Clark <james.clark@arm.com>
Cc: mingo@redhat.com, acme@kernel.org, mark.rutland@arm.com,
alexander.shishkin@linux.intel.com, jolsa@redhat.com,
namhyung@kernel.org, linux-perf-users@vger.kernel.org,
leo.yan@linaro.com, Suzuki.Poulose@arm.com,
Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/1] perf/core: Wake up parent event if inherited event has no ring buffer
Date: Tue, 25 Jan 2022 20:12:58 +0100 [thread overview]
Message-ID: <YfBLusfOk9fpIqqI@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <a4b64cff-f3f1-e6ad-38e9-b65a113ce561@arm.com>
On Mon, Jan 24, 2022 at 02:58:18PM +0000, James Clark wrote:
> > Would this be the better patch?
>
> Yes I tested this and it also works.
Excellent!
> There is one other suspicious access
> of ->rb followed by if(rb) here in perf_poll(), but maybe it works out ok?
>
> mutex_lock(&event->mmap_mutex);
> rb = event->rb;
> if (rb)
> events = atomic_xchg(&rb->poll, 0);
>
That case must be good since it is the event from a file. Those cannot
be clones.
> We also have a Perf self test that covers this failure for Arm SPE now, I'm not
> sure if I should post that separately or with your new version of this fix?
They'd be routed through separate trees anyway, Arnaldo takes the
userspace stuff.
next prev parent reply other threads:[~2022-01-25 19:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-06 11:38 [RFC PATCH 0/1] " James Clark
2021-12-06 11:38 ` [RFC PATCH 1/1] " James Clark
2022-01-24 11:37 ` Ruben Ayrapetyan
2022-01-24 11:49 ` Peter Zijlstra
2022-01-24 14:58 ` James Clark
2022-01-25 19:12 ` Peter Zijlstra [this message]
2022-01-26 16:15 ` James Clark
2022-01-27 11:50 ` [tip: perf/urgent] perf: Always wake the parent event tip-bot2 for James Clark
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