lkml.org 
[lkml]   [2011]   [Jun]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH RESEND] scsi: don't use execute_in_process_context()
On Sat, Apr 30, 2011 at 04:56:02PM +0200, Tejun Heo wrote:
> SCSI is the only subsystem which uses execute_in_process_context() and
> its use is racy against module unload. ie. the reap work is not
> properly flushed and could still be running after the scsi module is
> unloaded.
>
> Although execute_in_process_context() can be more efficient when the
> caller already has a context, in this case, the call paths are quite
> cold and the difference is practically meaningless. With commit
> c8efcc25 (workqueue: allow chained queueing during destruction), the
> race condition can easily be fixed by using a dedicated workqueue and
> destroying it on module unload.
>
> Create and use scsi_wq instead of execute_in_process_context().
>
> * scsi_device->ew is replaced with release_work. scsi_target->ew is
> replaced with reap_work.
>
> * Both works are initialized with the respective release/reap function
> during device/target init. scsi_target_reap_usercontext() is moved
> upwards to avoid needing forward declaration.
>
> * scsi_alloc_target() now explicitly flushes the reap_work of the
> found dying target before putting it instead of depending on
> flush_scheduled_work().
>
> For more info on the issues, please read the following threads.
>
> http://thread.gmane.org/gmane.linux.scsi/62923
> http://thread.gmane.org/gmane.linux.kernel/1124773
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Steven Whitehouse <swhiteho@redhat.com>
> --
> James, can we please get rid of execute_in_process_context()? It
> didn't help the recent crash case which was a separate issue but
> didn't break anything either, and this is one of the last several
> users of flush_scheduled_work() that I really want to remove.

(resending due to devlivery failure on suse address)

James, ping.

--
tejun


\
 
 \ /
  Last update: 2011-06-15 12:23    [W:0.175 / U:0.332 seconds]
©2003-2014 Jasper Spaans. Advertise on this site