linux-kernel - [PATCH 1/1] perf record: Fix eternal wait for stillborn child

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Date:	Mon,  6 Dec 2010 18:25:04 -0200
From:	Arnaldo Carvalho de Melo <acme@...radead.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>, Mike Galbraith <efault@....de>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>,
	Tom Zanussi <tzanussi@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 1/1] perf record: Fix eternal wait for stillborn child

From: Arnaldo Carvalho de Melo <acme@...hat.com>

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

Acked-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Mike Galbraith <efault@....de>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Tom Zanussi <tzanussi@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/builtin-record.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index e2c2de2..564491f 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);
-- 
1.6.2.5

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