From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from perceval.ideasonboard.com ([213.167.242.64]:43290 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727474AbeG3Vc6 (ORCPT ); Mon, 30 Jul 2018 17:32:58 -0400 From: Laurent Pinchart To: Kieran Bingham Cc: linux-media@vger.kernel.org, Guennadi Liakhovetski , Olivier BRAUN , Troy Kisky , Randy Dunlap , Philipp Zabel , Mauro Carvalho Chehab , open list Subject: Re: [PATCH v4 4/6] media: uvcvideo: queue: Simplify spin-lock usage Date: Mon, 30 Jul 2018 22:57:00 +0300 Message-ID: <18698388.LcrgILxgHI@avalon> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-media-owner@vger.kernel.org List-ID: Hi Kieran, Thank you for the patch. On Tuesday, 27 March 2018 19:46:01 EEST Kieran Bingham wrote: > Both uvc_start_streaming(), and uvc_stop_streaming() are called from > userspace context, with interrupts enabled. As such, they do not need to > save the IRQ state, and can use spin_lock_irq() and spin_unlock_irq() > respectively. > > Signed-off-by: Kieran Bingham > > --- > > v4: > - Rebase to v4.16 (linux-media/master) > > drivers/media/usb/uvc/uvc_queue.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/drivers/media/usb/uvc/uvc_queue.c > b/drivers/media/usb/uvc/uvc_queue.c index adcc4928fae4..698d9a5a5aae 100644 > --- a/drivers/media/usb/uvc/uvc_queue.c > +++ b/drivers/media/usb/uvc/uvc_queue.c > @@ -169,7 +169,6 @@ static int uvc_start_streaming(struct vb2_queue *vq, > unsigned int count) { > struct uvc_video_queue *queue = vb2_get_drv_priv(vq); > struct uvc_streaming *stream = uvc_queue_to_stream(queue); > - unsigned long flags; > int ret; > > queue->buf_used = 0; > @@ -178,9 +177,9 @@ static int uvc_start_streaming(struct vb2_queue *vq, > unsigned int count) if (ret == 0) > return 0; > > - spin_lock_irqsave(&queue->irqlock, flags); > + spin_lock_irq(&queue->irqlock); > uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED); > - spin_unlock_irqrestore(&queue->irqlock, flags); > + spin_unlock_irq(&queue->irqlock); > > return ret; > } > @@ -188,14 +187,13 @@ static int uvc_start_streaming(struct vb2_queue *vq, > unsigned int count) static void uvc_stop_streaming(struct vb2_queue *vq) > { > struct uvc_video_queue *queue = vb2_get_drv_priv(vq); > - unsigned long flags; > > if (vq->type != V4L2_BUF_TYPE_META_CAPTURE) > uvc_video_enable(uvc_queue_to_stream(queue), 0); > > - spin_lock_irqsave(&queue->irqlock, flags); > + spin_lock_irq(&queue->irqlock); > uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR); > - spin_unlock_irqrestore(&queue->irqlock, flags); > + spin_unlock_irq(&queue->irqlock); > } I think you missed my comment that stated > Please add a one-line comment above both functions to state > > /* Must be called with interrupts enabled. */ Philipp Zabel commented that you could also add lockdep_assert_irqs_enabled(), and I think that's a good idea. I'll let you decide whether to do both, or only add lockdep_assert_irqs_enabled(), I'm fine with either option. With this fixed, Reviewed-by: Laurent Pinchart > static const struct vb2_ops uvc_queue_qops = { -- Regards, Laurent Pinchart