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| author | Stephane Eranian <eranian@google.com> | 2013-06-04 17:44:26 +0200 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2013-07-08 17:36:33 -0300 |
| commit | d07f0b120642f442d81a61f68a9325fb7717004f (patch) | |
| tree | 0a0c3e465c98439a4ab98bbdb21892422b994ca1 /tools | |
| parent | 079787f209416416383c74ea5d5044be2d586f5e (diff) | |
| download | linux-d07f0b120642f442d81a61f68a9325fb7717004f.tar.gz | |
perf stat: Avoid sending SIGTERM to random processes
This patch fixes a problem with perf stat whereby on termination it may send a SIGTERM signal to random processes on systems with high PID recycling. I got some actual bug reports on this. There is race between the SIGCHLD and sig_atexit() handlers. This patch addresses this problem by clearing child_pid in the SIGCHLD handler. Signed-off-by: Stephane Eranian <eranian@google.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20130604154426.GA2928@quad Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/perf/builtin-stat.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index 7e910bab1097..95768afaae3e 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -87,7 +87,7 @@ static int run_count = 1; static bool no_inherit = false; static bool scale = true; static enum aggr_mode aggr_mode = AGGR_GLOBAL; -static pid_t child_pid = -1; +static volatile pid_t child_pid = -1; static bool null_run = false; static int detailed_run = 0; static bool big_num = true; @@ -1148,13 +1148,34 @@ static void skip_signal(int signo) done = 1; signr = signo; + /* + * render child_pid harmless + * won't send SIGTERM to a random + * process in case of race condition + * and fast PID recycling + */ + child_pid = -1; } static void sig_atexit(void) { + sigset_t set, oset; + + /* + * avoid race condition with SIGCHLD handler + * in skip_signal() which is modifying child_pid + * goal is to avoid send SIGTERM to a random + * process + */ + sigemptyset(&set); + sigaddset(&set, SIGCHLD); + sigprocmask(SIG_BLOCK, &set, &oset); + if (child_pid != -1) kill(child_pid, SIGTERM); + sigprocmask(SIG_SETMASK, &oset, NULL); + if (signr == -1) return; |