Re: [PATCH] compat: fix system crash on 2.6.35 when flushing work

["C. McPherson" <ccmcphe@verizon.net>]

Zefir:
Thanks a lot for this reference. All my systems are running Ubuntu 
10.04/10.10. I was updating our compat-wireless with the stable 
compat-wireless 3.5
and came across this crash in our testing lab. I added your patch and 
the stable compat-wireless 3.5 is now working with our Ubuntu.

-Tex


On 07/13/2012 04:38 AM, Zefir Kurtisi wrote:
> Ubuntu 10.10 stock kernel (2.6.35-22-generic) crashes in
> compat_flush_scheduled_work(), that is called e.g. when
> mac80211 module is unloaded.
>
> The problem was introduced with 80bf8a83
> compat: backport system work queues system_wq and system_long_wq
>
> The crash happens in compat_flush_scheduled_work() where both
> flush_workqueue() and flush_scheduled_work() are called successively.
> Removing one of them resolves the issue.
>
> All compat-wireless tarballs after 2012-03-18 are affected.
>
> Signed-off-by: Zefir Kurtisi <zefir.kurtisi@neratec.com>
> ---
>   compat/compat-2.6.36.c |    1 -
>   1 files changed, 0 insertions(+), 1 deletions(-)
>
> diff --git a/compat/compat-2.6.36.c b/compat/compat-2.6.36.c
> index 9190ecd..8f25be0 100644
> --- a/compat/compat-2.6.36.c
> +++ b/compat/compat-2.6.36.c
> @@ -140,7 +140,6 @@ void compat_flush_scheduled_work(void)
>   	 * go with the old kernel's one first for now (keventd_wq) and
>   	 * if think its reasonable later we can flip this around.
>   	 */
> -	flush_workqueue(system_wq);
>   	flush_scheduled_work();
>   }
>   EXPORT_SYMBOL_GPL(compat_flush_scheduled_work);