summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorAnand K Mistry <amistry@google.com>2021-09-29 17:04:21 +1000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-10-17 10:04:44 +0200
commit5ee326b8c3535ac93a3761fdf57a15ae48a80aef (patch)
treed805ba28c109f9635b92948419d9217dd08cf202
parent9d35377f87e165e99a2cabbba5c1e245ef1ecdea (diff)
downloadlinux-stable-5ee326b8c3535ac93a3761fdf57a15ae48a80aef.tar.gz
linux-stable-5ee326b8c3535ac93a3761fdf57a15ae48a80aef.tar.bz2
linux-stable-5ee326b8c3535ac93a3761fdf57a15ae48a80aef.zip
perf/x86: Reset destroy callback on event init failure
[ Upstream commit 02d029a41dc986e2d5a77ecca45803857b346829 ] 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 Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--arch/x86/kernel/cpu/perf_event.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index b983d3dc4e6c..851fbdb99767 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -2001,6 +2001,7 @@ static int x86_pmu_event_init(struct perf_event *event)
if (err) {
if (event->destroy)
event->destroy(event);
+ event->destroy = NULL;
}
if (ACCESS_ONCE(x86_pmu.attr_rdpmc))