[media] pvrusb2: Remove deprecated create_singlethread_workqueue
authorBhaktipriya Shridhar <bhaktipriya96@gmail.com>
Sat, 16 Jul 2016 08:32:34 +0000 (05:32 -0300)
committerMauro Carvalho Chehab <mchehab@s-opensource.com>
Wed, 24 Aug 2016 12:28:39 +0000 (09:28 -0300)
commit29a3006e5209b5dde2d370b8de1e8c18c14040e7
tree479704cdcdf342dc0ee81d5864bf309434070adf
parent50d286470cd5dd6a855a34b099dbed85b58688ed
[media] pvrusb2: Remove deprecated create_singlethread_workqueue

The workqueue "workqueue" is involved in polling the pvrusb2 hardware
(pvr2_hdw).

It has a single work item(&hdw->workpoll) and hence doesn't require
ordering. Also, it is not being used on a memory reclaim path.
Hence, the singlethreaded workqueue has been replaced with the use of
system_wq.

System workqueues have been able to handle high level of concurrency
for a long time now and hence it's not required to have a singlethreaded
workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue
created with create_singlethread_workqueue(), system_wq allows multiple
work items to overlap executions even on the same CPU; however, a
per-cpu workqueue doesn't have any CPU locality or global ordering
guarantee unless the target CPU is explicitly specified and thus the
increase of local concurrency shouldn't make any difference.

Work item has been flushed in pvr2_hdw_destroy to ensure that there are no
pending tasks while disconnecting the driver.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
drivers/media/usb/pvrusb2/pvrusb2-hdw-internal.h
drivers/media/usb/pvrusb2/pvrusb2-hdw.c