perf_events, trace: Fix probe unregister race
tracepoint_probe_unregister() does not synchronize against the probe
callbacks, so do that explicitly. This properly serializes the callbacks
and the free of the data used therein.
Also, use this_cpu_ptr() where possible.
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1274438476.1674.1702.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index cb6f365..49c7abf 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -116,7 +116,7 @@
if (WARN_ON_ONCE(!list))
return -EINVAL;
- list = per_cpu_ptr(list, smp_processor_id());
+ list = this_cpu_ptr(list);
hlist_add_head_rcu(&p_event->hlist_entry, list);
return 0;
@@ -142,6 +142,12 @@
tp_event->class->perf_probe,
tp_event);
+ /*
+ * Ensure our callback won't be called anymore. See
+ * tracepoint_probe_unregister() and __DO_TRACE().
+ */
+ synchronize_sched();
+
free_percpu(tp_event->perf_events);
tp_event->perf_events = NULL;
@@ -169,7 +175,7 @@
if (*rctxp < 0)
return NULL;
- raw_data = per_cpu_ptr(perf_trace_buf[*rctxp], smp_processor_id());
+ raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);
/* zero the dead bytes from align to not leak stack to user */
memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));