diff options
| author | Peter Zijlstra | 2013-10-03 16:02:23 +0200 |
|---|---|---|
| committer | Ingo Molnar | 2013-10-04 09:58:53 +0200 |
| commit | 9886167d20c0720dcfb01e62cdff4d906b226f43 (patch) | |
| tree | dff8fb937ae2c73fe474263da0e906aa77d6ae54 /kernel | |
| parent | cac6653529eeac9b661fc8342c47d849c3adb085 (diff) | |
perf: Fix perf_pmu_migrate_context
While auditing the list_entry usage due to a trinity bug I found that
perf_pmu_migrate_context violates the rules for
perf_event::event_entry.
The problem is that perf_event::event_entry is a RCU list element, and
hence we must wait for a full RCU grace period before re-using the
element after deletion.
Therefore the usage in perf_pmu_migrate_context() which re-uses the
entry immediately is broken. For now introduce another list_head into
perf_event for this specific usage.
This doesn't actually fix the trinity report because that never goes
through this code.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-mkj72lxagw1z8fvjm648iznw@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index cb4238e85b38..d49a9d29334c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7234,15 +7234,15 @@ void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu) perf_remove_from_context(event); unaccount_event_cpu(event, src_cpu); put_ctx(src_ctx); - list_add(&event->event_entry, &events); + list_add(&event->migrate_entry, &events); } mutex_unlock(&src_ctx->mutex); synchronize_rcu(); mutex_lock(&dst_ctx->mutex); - list_for_each_entry_safe(event, tmp, &events, event_entry) { - list_del(&event->event_entry); + list_for_each_entry_safe(event, tmp, &events, migrate_entry) { + list_del(&event->migrate_entry); if (event->state >= PERF_EVENT_STATE_OFF) event->state = PERF_EVENT_STATE_INACTIVE; account_event_cpu(event, dst_cpu); |