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| author | Anand K Mistry <amistry@google.com> | 2021-09-29 10:04:21 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-10-01 14:57:54 +0300 |
| commit | 02d029a41dc986e2d5a77ecca45803857b346829 (patch) | |
| tree | 70434a4e4ac3048800851eca69bb0d5d230895f3 /arch | |
| parent | e4e737bb5c170df6135a127739a9e6148ee3da82 (diff) | |
| download | linux-02d029a41dc986e2d5a77ecca45803857b346829.tar.xz | |
perf/x86: Reset destroy callback on event init failure
perf_init_event tries multiple init callbacks and does not reset the
event state between tries. When x86_pmu_event_init runs, it
unconditionally sets the destroy callback to hw_perf_event_destroy. On
the next init attempt after x86_pmu_event_init, in perf_try_init_event,
if the pmu's capabilities includes PERF_PMU_CAP_NO_EXCLUDE, the destroy
callback will be run. However, if the next init didn't set the destroy
callback, hw_perf_event_destroy will be run (since the callback wasn't
reset).
Looking at other pmu init functions, the common pattern is to only set
the destroy callback on a successful init. Resetting the callback on
failure tries to replicate that pattern.
This was discovered after commit f11dd0d80555 ("perf/x86/amd/ibs: Extend
PERF_PMU_CAP_NO_EXCLUDE to IBS Op") when the second (and only second)
run of the perf tool after a reboot results in 0 samples being
generated. The extra run of hw_perf_event_destroy results in
active_events having an extra decrement on each perf run. The second run
has active_events == 0 and every subsequent run has active_events < 0.
When active_events == 0, the NMI handler will early-out and not record
any samples.
Signed-off-by: Anand K Mistry <amistry@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210929170405.1.I078b98ee7727f9ae9d6df8262bad7e325e40faf0@changeid
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/events/core.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 2a57dbed4894..6dfa8ddaa60f 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2465,6 +2465,7 @@ static int x86_pmu_event_init(struct perf_event *event) if (err) { if (event->destroy) event->destroy(event); + event->destroy = NULL; } if (READ_ONCE(x86_pmu.attr_rdpmc) && |