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SubjectRe: [PATCH 1/1] w1: fix oops when w1_search is called from netlink connector
Hi

Marcin, thanks a lot for the fix, I have to sorry I'm not on this bug yet :(
Sven confirmed patch fixes it, Greg please pull it into your tree.

I believe this is stable material.
Thanks everyone.

Acked-by: Evgeniy Polyakov <zbr@ioremap.net>

On Sat, Mar 02, 2013 at 02:50:15PM +0100, Marcin Jurkowski (marcin1j@gmail.com) wrote:
> On Sat, Mar 02, 2013 at 10:45:10AM +0100, Sven Geggus wrote:
> > This is the bad commit I found doing git bisect:
> > 04f482faf50535229a5a5c8d629cf963899f857c is the first bad commit
> > commit 04f482faf50535229a5a5c8d629cf963899f857c
> > Author: Patrick McHardy <kaber@trash.net>
> > Date: Mon Mar 28 08:39:36 2011 +0000
>
> Good job. I was too lazy to bisect for bad commit;)
>
> Reading the code I found problematic kthread_should_stop call from netlink
> connector which causes the oops. After applying a patch, I've been testing
> owfs+w1 setup for nearly two days and it seems to work very reliable (no
> hangs, no memleaks etc).
> More detailed description and possible fix is given below:
>
> Function w1_search can be called from either kthread or netlink callback.
> While the former works fine, the latter causes oops due to kthread_should_stop
> invocation.
>
> This patch adds a check if w1_search is serving netlink command, skipping
> kthread_should_stop invocation if so.
>
> Signed-off-by: Marcin Jurkowski <marcin1j@gmail.com>
> ---
> drivers/w1/w1.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
> index 7994d933..7e2220d 100644
> --- a/drivers/w1/w1.c
> +++ b/drivers/w1/w1.c
> @@ -924,7 +924,8 @@ void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb
> tmp64 = (triplet_ret >> 2);
> rn |= (tmp64 << i);
>
> - if (kthread_should_stop()) {
> + /* ensure we're called from kthread and not by netlink callback */
> + if (!dev->priv && kthread_should_stop()) {
> mutex_unlock(&dev->bus_mutex);
> dev_dbg(&dev->dev, "Abort w1_search\n");
> return;
> --
> 1.7.12.4

--
Evgeniy Polyakov


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