perf annotate: Fix segmentation fault

Linus reported this perf annotate segfault:

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

       	#0  map__clone (self=<value optimized out>) at builtin-annotate.c:236
       	#1  thread__fork (self=<value optimized out>) 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 <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 0 deletions

diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index 1dba568e1941..343e7b14bf01 100644
--- 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;