UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

[media] zc3xx: Remove deprecated create_singlethread_workqueue 

The workqueue "work_thread" is involved in updating parameters for
transfers. It has a single work item(&sd->work) 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 sd_stop0() to ensure that there are no
pending tasks while disconnecting the driver.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Bhaktipriya Shridhar 2016-07-09 04:52:29 -03:00 committed by Mauro Carvalho Chehab
parent e0f80d8d62
commit f7cf0362f6
1 changed files with 4 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/media/usb/gspca/zc3xx.c
View File

@ -53,7 +53,6 @@ struct sd {
struct v4l2_ctrl *jpegqual;
struct work_struct work;
struct workqueue_struct *work_thread;
u8 reg08; /* webcam compression quality */
@ -6826,8 +6825,7 @@ static int sd_start(struct gspca_dev *gspca_dev)
return gspca_dev->usb_err;
/* Start the transfer parameters update thread */
sd->work_thread = create_singlethread_workqueue(KBUILD_MODNAME);
queue_work(sd->work_thread, &sd->work);
schedule_work(&sd->work);
return 0;
}
@ -6838,12 +6836,9 @@ static void sd_stop0(struct gspca_dev *gspca_dev)
{
struct sd *sd = (struct sd *) gspca_dev;
if (sd->work_thread != NULL) {
mutex_unlock(&gspca_dev->usb_lock);
destroy_workqueue(sd->work_thread);
mutex_lock(&gspca_dev->usb_lock);
sd->work_thread = NULL;
}
mutex_unlock(&gspca_dev->usb_lock);
flush_work(&sd->work);
mutex_lock(&gspca_dev->usb_lock);
if (!gspca_dev->present)
return;
send_unknown(gspca_dev, sd->sensor);