From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Mon, 26 Oct 2009 21:23:17 +0000 (-0200)
Subject: perf record: Fix race where process can disappear while reading its /proc/pid/tasks
X-Git-Tag: firefly_0821_release~9833^2~3628^2~288^2~47
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7f3bedcc93f935631d2363f23de1cc80f04fdf3e;p=firefly-linux-kernel-4.4.55.git

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>
---

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);