* [PATCH 2/2] notifiers: double register detection
@ 2016-09-21 12:33 Vasily Averin
2016-10-27 10:44 ` Vasily Averin
0 siblings, 1 reply; 2+ messages in thread
From: Vasily Averin @ 2016-09-21 12:33 UTC (permalink / raw)
To: linux-kernel, linux-nfs; +Cc: J. Bruce Fields, Jeff Layton, Scott Mayhew
WARN_ON should help to detect double register of the same notifiers
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
---
kernel/notifier.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/notifier.c b/kernel/notifier.c
index fd2c9ac..e02b2f0 100644
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -22,6 +22,7 @@ static int notifier_chain_register(struct notifier_block **nl,
struct notifier_block *n)
{
while ((*nl) != NULL) {
+ WARN_ON((*nl) == n);
if (n->priority > (*nl)->priority)
break;
nl = &((*nl)->next);
--
1.9.1
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [PATCH 2/2] notifiers: double register detection
2016-09-21 12:33 [PATCH 2/2] notifiers: double register detection Vasily Averin
@ 2016-10-27 10:44 ` Vasily Averin
0 siblings, 0 replies; 2+ messages in thread
From: Vasily Averin @ 2016-10-27 10:44 UTC (permalink / raw)
To: linux-kernel, Andrew Morton
Dear Andrew,
could you please pick up this patch?
It helps to detect double register of the same notifiers.
This kind of problem can lead to unexpected failures (some notifiers can be not called),
endless cycles, memory corruption or crashes.
Initially I've found such cases in OpenVZ kernels in our custom code,
then found similar bug in mainline nfsd (commit 1eca45f8)
On 21.09.2016 15:33, Vasily Averin wrote:
> WARN_ON should help to detect double register of the same notifiers
>
> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
> ---
> kernel/notifier.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/notifier.c b/kernel/notifier.c
> index fd2c9ac..e02b2f0 100644
> --- a/kernel/notifier.c
> +++ b/kernel/notifier.c
> @@ -22,6 +22,7 @@ static int notifier_chain_register(struct notifier_block **nl,
> struct notifier_block *n)
> {
> while ((*nl) != NULL) {
> + WARN_ON((*nl) == n);
> if (n->priority > (*nl)->priority)
> break;
> nl = &((*nl)->next);
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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