perf annotate: Fix segmentation fault

Ingo Molnar · Ingo Molnar · commit 15f3fa4e7f60 · 2009-08-18T14:00:52.000+02:00
Linus reported this perf annotate segfault:

        [torvalds@nehalem git]$ perf annotate unmap_vmas
        Segmentation fault

       	#0  map__clone (self=&lt;value optimized out&gt;) at builtin-annotate.c:236
       	#1  thread__fork (self=&lt;value optimized out&gt;) at builtin-annotate.c:372

The bug here was that builtin-annotate.c was a copy of
builtin-report.c and a threading related fix to builtin-report.c
didnt get propagated to builtin-annotate.c ...

Reported-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: Mike Galbraith &lt;efault@gmx.de&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
LKML-Reference: &lt;new-submission&gt;
Signed-off-by: Ingo Molnar &lt;mingo@elte.hu&gt;
diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
@@ -980,6 +980,13 @@ process_fork_event(event_t *event, unsigned long offset, unsigned long head)
 		(void *)(long)(event->header.size),
 		event->fork.pid, event->fork.ppid);
 
+	/*
+	 * A thread clone will have the same PID for both
+	 * parent and child.
+	 */
+	if (thread == parent)
+		return 0;
+
 	if (!thread || !parent || thread__fork(thread, parent)) {
 		dprintf("problem processing PERF_EVENT_FORK, skipping event.\n");
 		return -1;
