[ 3.5.y.z extended stable ] Patch "w1: fix oops when w1_search is called from netlink connector" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    w1: fix oops when w1_search is called from netlink connector

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 98cc54a4221106c9bec5d90397a63e6a38a3b031 Mon Sep 17 00:00:00 2001
From: Marcin Jurkowski <marcin1j at gmail.com>
Date: Sat, 2 Mar 2013 14:50:15 +0100
Subject: [PATCH] w1: fix oops when w1_search is called from netlink connector

commit 9d1817cab2f030f6af360e961cc69bb1da8ad765 upstream.

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 at 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 at gmail.com>
Acked-by: Evgeniy Polyakov <zbr at ioremap.net>
Cc: Josh Boyer <jwboyer at gmail.com>
Tested-by: Sven Geggus <lists at fuchsschwanzdomain.de>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
[ luis: adjust context ]
Luis Henriques <luis.henriques at canonical.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 2f2e894..2b48bd2 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -928,7 +928,8 @@ 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()) {
 				dev_dbg(&dev->dev, "Abort w1_search\n");
 				return;
 			}
--
1.8.1.2