[PATCH] stop_machine: fix race with return value (fixes Bug #11989)

[PATCH] stop_machine: fix race with return value (fixes Bug #11989)

[Rusty Russell]

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Bug #11989: Suspend failure on NForce4-based boards due to chanes in stop_machine
We should not access active.fnret outside the lock; in theory the nextstop_machine could overwrite it.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>Tested-by: "Rafael J. Wysocki" <rjw@sisk.pl>--- kernel/stop_machine.c |    5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff -r d7c9a15da615 kernel/stop_machine.c--- a/kernel/stop_machine.c	Mon Nov 10 09:47:45 2008 +1100+++ b/kernel/stop_machine.c	Tue Nov 11 23:19:47 2008 +1030@@ -112,7 +112,7 @@ int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus) { 	struct work_struct *sm_work;-	int i;+	int i, ret;  	/* Set up initial state. */ 	mutex_lock(&lock);@@ -137,8 +137,9 @@ 	/* This will release the thread on our CPU. */ 	put_cpu(); 	flush_workqueue(stop_machine_wq);+	ret = active.fnret; 	mutex_unlock(&lock);-	return active.fnret;+	return ret; }  int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus)\0ÿôèº{.nÇ+‰·Ÿ®‰­†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a­¢f£¢·hšïêÿ‘êçz_è®\x03(­éšŽŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨è­Ú&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥

Re: [PATCH] stop_machine: fix race with return value (fixes Bug #11989)

[Heiko Carstens]

On Mon, Nov 17, 2008 at 08:22:18AM +1030, Rusty Russell wrote:
> Bug #11989: Suspend failure on NForce4-based boards due to chanes in stop_machine
> 
> We should not access active.fnret outside the lock; in theory the next
> stop_machine could overwrite it.
> 
> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
> Tested-by: "Rafael J. Wysocki" <rjw@sisk.pl>
> ---
>  kernel/stop_machine.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Thank you, Rusty, for finding and fixing this one as well!