diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2023-10-18 13:56:54 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-10-25 11:53:24 +0200 |
| commit | 7252c8b981853bb8930de44fab924f947362683f (patch) | |
| tree | 47f97b5aaca9a51fd209a071bd298dfe284ddedc /include | |
| parent | 32279bbbd8110416ed6d65f28ae20d738f6333be (diff) | |
perf: Disallow mis-matched inherited group reads
commit 32671e3799ca2e4590773fd0e63aaa4229e50c06 upstream.
Because group consistency is non-atomic between parent (filedesc) and children
(inherited) events, it is possible for PERF_FORMAT_GROUP read() to try and sum
non-matching counter groups -- with non-sensical results.
Add group_generation to distinguish the case where a parent group removes and
adds an event and thus has the same number, but a different configuration of
events as inherited groups.
This became a problem when commit fa8c269353d5 ("perf/core: Invert
perf_read_group() loops") flipped the order of child_list and sibling_list.
Previously it would iterate the group (sibling_list) first, and for each
sibling traverse the child_list. In this order, only the group composition of
the parent is relevant. By flipping the order the group composition of the
child (inherited) events becomes an issue and the mis-match in group
composition becomes evident.
That said; even prior to this commit, while reading of a group that is not
equally inherited was not broken, it still made no sense.
(Ab)use ECHILD as error return to indicate issues with child process group
composition.
Fixes: fa8c269353d5 ("perf/core: Invert perf_read_group() loops")
Reported-by: Budimir Markovic <markovicbudimir@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20231018115654.GK33217@noisy.programming.kicks-ass.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/perf_event.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index c99e2f851d31..4c7409e23318 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -607,6 +607,7 @@ struct perf_event { /* The cumulative AND of all event_caps for events in this group. */ int group_caps; + unsigned int group_generation; struct perf_event *group_leader; struct pmu *pmu; void *pmu_private; |