perf record: Fix eternal wait for stillborn child

When execvp fails to find the specified command on the path we won't get
SIGCHLD, so send a SIGUSR1 and exit right away.

Current situation would require a SIGINT performed by the user and would
produce meaningless summary.

Now:

[acme@emilia linux]$ ./foo
-bash: ./foo: No such file or directory
[acme@emilia linux]$ perf record ./foo
./foo: No such file or directory
[acme@emilia linux]$

Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index e2c2de201eec..564491fa18b2 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -197,7 +197,7 @@ static void sig_atexit(void)
         if (child_pid > 0)
                 kill(child_pid, SIGTERM);
 
-        if (signr == -1)
+        if (signr == -1 || signr == SIGUSR1)
                 return;
 
         signal(signr, SIG_DFL);
@@ -515,6 +515,7 @@ static int __cmd_record(int argc, const char **argv)
         atexit(sig_atexit);
         signal(SIGCHLD, sig_handler);
         signal(SIGINT, sig_handler);
+        signal(SIGUSR1, sig_handler);
 
         if (forks && (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0)) {
                 perror("failed to create pipes");
@@ -606,6 +607,7 @@ static int __cmd_record(int argc, const char **argv)
                         execvp(argv[0], (char **)argv);
 
                         perror(argv[0]);
+                        kill(getppid(), SIGUSR1);
                         exit(-1);
                 }
 
@@ -762,7 +764,7 @@ static int __cmd_record(int argc, const char **argv)
                 }
         }
 
-        if (quiet)
+        if (quiet || signr == SIGUSR1)
                 return 0;
 
         fprintf(stderr, "[ perf record: Woken up %ld times to write data ]\n", waking);