From: James Clark <james.clark@arm.com>
To: linux-perf-users@vger.kernel.org, peterz@infradead.org,
ravi.bangoria@amd.com
Cc: James Clark <james.clark@arm.com>, Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
linux-kernel@vger.kernel.org
Subject: [PATCH 0/1] perf: Fix warning from concurrent read/write of perf_event_pmu_context
Date: Fri, 27 Jan 2023 14:31:40 +0000 [thread overview]
Message-ID: <20230127143141.1782804-1-james.clark@arm.com> (raw)
Hi Peter and Ravi,
I came across this issue, and I also found there was a syzbot report
for it and linked it on the commit. I have one question about the fix,
where I had to remove the if (epc->ctx) from put_pmu_ctx(). I assume
this was added for a reason, but I can't see where it's not ever set?
Unless it's removed, the function got a lot more complicated to take
the lock before the reference decrement.
Also now I think the atomic type for epc->refcount is redundant,
because everything is always done with the lock held. Except for
get_pmu_ctx(), but that is just a read for a warning. So unless you
think the scope of my extra locking can be reduced, I would probably
also send a commit to remove that as well.
Thanks
James
James Clark (1):
perf: Fix warning from concurrent read/write of perf_event_pmu_context
kernel/events/core.c | 42 ++++++++++++++++++++----------------------
1 file changed, 20 insertions(+), 22 deletions(-)
base-commit: 5912e15f25d6d584f3b8449e0b6a244a0f4f0903
--
2.39.1
next reply other threads:[~2023-01-27 14:32 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-27 14:31 James Clark [this message]
2023-01-27 14:31 ` [PATCH 1/1] perf: Fix warning from concurrent read/write of perf_event_pmu_context James Clark
2023-01-30 5:49 ` Ravi Bangoria
2023-01-31 8:25 ` Ravi Bangoria
2023-01-31 13:31 ` Peter Zijlstra
2023-02-01 10:49 ` James Clark
2023-02-01 16:10 ` [tip: perf/urgent] perf: Fix perf_event_pmu_context serialization tip-bot2 for James Clark
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