From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pa0-f65.google.com ([209.85.220.65]:34329 "EHLO mail-pa0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750728AbcGBLBy (ORCPT ); Sat, 2 Jul 2016 07:01:54 -0400 Date: Sat, 2 Jul 2016 16:19:28 +0530 From: Bhaktipriya Shridhar To: Hans de Goede , Mauro Carvalho Chehab Cc: Tejun Heo , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] [media] zc3xx: Remove deprecated create_singlethread_workqueue Message-ID: <20160702104928.GA2672@Karyakshetra> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-media-owner@vger.kernel.org List-ID: 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 --- drivers/media/usb/gspca/zc3xx.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/drivers/media/usb/gspca/zc3xx.c b/drivers/media/usb/gspca/zc3xx.c index c5d8ee6..ebdfed4d6 100644 --- a/drivers/media/usb/gspca/zc3xx.c +++ b/drivers/media/usb/gspca/zc3xx.c @@ -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); + schedule_work(&sd->work); + mutex_lock(&gspca_dev->usb_lock); if (!gspca_dev->present) return; send_unknown(gspca_dev, sd->sensor); -- 2.1.4