linux-kernel - Re: [PATCH 1/1] w1: fix oops when w1_search is called from netlink connector

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Date:	Mon, 4 Mar 2013 00:54:52 +0400
From:	Evgeniy Polyakov <zbr@...emap.net>
To:	Marcin Jurkowski <marcin1j@...il.com>
Cc:	Sven Geggus <lists@...hsschwanzdomain.de>,
	linux-kernel@...r.kernel.org, GregKH <greg@...ah.com>
Subject: Re: [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@...emap.net>

On Sat, Mar 02, 2013 at 02:50:15PM +0100, Marcin Jurkowski (marcin1j@...il.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@...sh.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@...il.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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