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    Subject[ 19/40] w1: fix oops when w1_search is called from netlink connector
    Date
    3.0-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Marcin Jurkowski <marcin1j@gmail.com>

    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@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>
    Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
    Cc: Josh Boyer <jwboyer@gmail.com>
    Tested-by: Sven Geggus <lists@fuchsschwanzdomain.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/w1/w1.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/drivers/w1/w1.c
    +++ b/drivers/w1/w1.c
    @@ -918,7 +918,8 @@ void w1_search(struct w1_master *dev, u8
    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;
    }



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