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>

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index e2c2de201eecafc5490caba7637f0eefbcbc0b46..564491fa18b27838dd79125954bc744f51f7fe2c 100644 (file)
--- 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);