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perf_events, trace: Fix probe unregister race

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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>
This commit is contained in:
Peter Zijlstra
2010-05-21 12:31:09 +02:00
committed by Ingo Molnar
parent 8a49542c05
commit 3771f07711
4 changed files with 13 additions and 7 deletions
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kernel/trace/trace_event_perf.c
+8 -2
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@@ -116,7 +116,7 @@ int perf_trace_enable(struct perf_event *p_event)
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 @@ void perf_trace_destroy(struct perf_event *p_event)
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 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
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));