perf record: Fix race where process can disappear while reading its /proc/pid/tasks

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1256592199-9608-1-git-send-email-acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 0 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index ac5ddfff4456..9e1638cc19c8 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -206,6 +206,7 @@ static pid_t pid_synthesize_comm_event(pid_t pid, int full)
 
         fp = fopen(filename, "r");
         if (fp == NULL) {
+out_race:       
                 /*
                  * We raced with a task exiting - just return:
                  */
@@ -247,6 +248,9 @@ static pid_t pid_synthesize_comm_event(pid_t pid, int full)
         snprintf(filename, sizeof(filename), "/proc/%d/task", pid);
 
         tasks = opendir(filename);
+        if (tasks == NULL)
+                goto out_race;
+
         while (!readdir_r(tasks, &dirent, &next) && next) {
                 char *end;
                 pid = strtol(dirent.d_name, &end, 10);