From: Wanlong Gao <gaowanlong@cn.fujitsu.com>
To: Tomas Winkler <tomas.winkler@intel.com>
Cc: gregkh@linuxfoundation.org, hdegoede@redhat.com, wim@iguana.be,
arnd@arndb.de, alan@linux.intel.com,
linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org,
Borislav Petkov <bp@alien8.de>,
Jerry Snitselaar <jerry.snitselaar@oracle.com>
Subject: Re: [char-misc for 3.8] mei: avoid oops in watchdog unregister code path
Date: Mon, 17 Dec 2012 10:39:15 +0800 [thread overview]
Message-ID: <50CE85D3.3070209@cn.fujitsu.com> (raw)
In-Reply-To: <1355656997-30659-1-git-send-email-tomas.winkler@intel.com>
On 12/16/2012 07:23 PM, Tomas Winkler wrote:
> With commit c7d3df3 "mei: use internal watchdog device registration
> tracking" will crash the kernel on shutdown path on systems
> where ME watchdog is not present.
> Since the watchdog was never initialized in such case
> the WDOG_UNREGISTERED bit is never set and the system
> crashes on access to uninitialized variables down the path.
>
> To solve the issue we query for NULL on watchdog driver driver_data
> to check whether the device is registered. This is handled in the
> driver and doesn't depend on watchdog core internals.
>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Wanlong Gao <gaowanlong@cn.fujitsu.com>
> Signed-off-by: Jerry Snitselaar <jerry.snitselaar@oracle.com>
> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Fixed the panic here, thank you.
Tested-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
> ---
> drivers/misc/mei/wd.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/misc/mei/wd.c b/drivers/misc/mei/wd.c
> index 636409f..9299a8c 100644
> --- a/drivers/misc/mei/wd.c
> +++ b/drivers/misc/mei/wd.c
> @@ -370,7 +370,7 @@ void mei_watchdog_register(struct mei_device *dev)
>
> void mei_watchdog_unregister(struct mei_device *dev)
> {
> - if (test_bit(WDOG_UNREGISTERED, &amt_wd_dev.status))
> + if (watchdog_get_drvdata(&amt_wd_dev) == NULL)
> return;
>
> watchdog_set_drvdata(&amt_wd_dev, NULL);
>
prev parent reply other threads:[~2012-12-17 2:59 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-16 11:23 [char-misc for 3.8] mei: avoid oops in watchdog unregister code path Tomas Winkler
2012-12-17 2:39 ` Wanlong Gao [this message]
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