perf_counter tools: Propagate signals properly

Currently report and stat catch SIGINT (and others) without altering
their exit state. This means that things like:

   while :; do perf stat ./foo ; done

Loops become hard-to-interrupt, because bash never sees perf terminate
due to interruption. Fix this.

Signed-off-by: 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>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/builtin-record.c

@@ -169,10 +169,21 @@ static void mmap_read(struct mmap_data *md)
 }
 
 static volatile int done = 0;
+static volatile int signr = -1;
 
 static void sig_handler(int sig)
 {
 	done = 1;
+	signr = sig;
+}
+
+static void sig_atexit(void)
+{
+	if (signr == -1)
+		return;
+
+	signal(signr, SIG_DFL);
+	kill(getpid(), signr);
 }
 
 static void pid_synthesize_comm_event(pid_t pid, int full)
@@ -459,6 +470,7 @@ static int __cmd_record(int argc, const char **argv)
 	} else for (i = 0; i < nr_cpus; i++)
 		open_counters(i, target_pid);
 
+	atexit(sig_atexit);
 	signal(SIGCHLD, sig_handler);
 	signal(SIGINT, sig_handler);
 

tools/perf/builtin-stat.c

@@ -296,8 +296,20 @@ static int do_perf_stat(int argc, const char **argv)
 	return 0;
 }
 
+static volatile int signr = -1;
+
 static void skip_signal(int signo)
 {
+	signr = signo;
+}
+
+static void sig_atexit(void)
+{
+	if (signr == -1)
+		return;
+
+	signal(signr, SIG_DFL);
+	kill(getpid(), signr);
 }
 
 static const char * const stat_usage[] = {
@@ -345,6 +357,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix)
 	 * What we want is for Ctrl-C to work in the exec()-ed
 	 * task, but being ignored by perf stat itself:
 	 */
+	atexit(sig_atexit);
 	signal(SIGINT,  skip_signal);
 	signal(SIGALRM, skip_signal);
 	signal(SIGABRT, skip_signal);