[3.13.y.z extended stable] Patch "[media] em28xx-v4l: give back all active video buffers to the vb2 core properly on streaming stop" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    [media] em28xx-v4l: give back all active video buffers to the vb2 core properly on streaming stop

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.10.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 9d96e8bd1761cacc16148039647dfc577e5e9e18 Mon Sep 17 00:00:00 2001
From: Frank Schaefer <fschaefer.oss at googlemail.com>
Date: Sat, 9 Aug 2014 06:37:20 -0300
Subject: [media] em28xx-v4l: give back all active video buffers to the vb2
 core properly on streaming stop
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit 627530c32a43283474e9dd3e954519410ffa033a upstream.

When a new video frame is started, the driver takes the next video buffer from
the list of active buffers and moves it to dev->usb_ctl.vid_buf / dev->usb_ctl.vbi_buf
for further processing.

On streaming stop we currently only give back the pending buffers from the list
but not the ones which are currently processed.

This causes the following warning from the vb2 core since kernel 3.15:

...
 ------------[ cut here ]------------
 WARNING: CPU: 1 PID: 2284 at drivers/media/v4l2-core/videobuf2-core.c:2115 __vb2_queue_cancel+0xed/0x150 [videobuf2_core]()
 [...]
 Call Trace:
  [<c0769c46>] dump_stack+0x48/0x69
  [<c0245b69>] warn_slowpath_common+0x79/0x90
  [<f925e4ad>] ? __vb2_queue_cancel+0xed/0x150 [videobuf2_core]
  [<f925e4ad>] ? __vb2_queue_cancel+0xed/0x150 [videobuf2_core]
  [<c0245bfd>] warn_slowpath_null+0x1d/0x20
  [<f925e4ad>] __vb2_queue_cancel+0xed/0x150 [videobuf2_core]
  [<f925fa35>] vb2_internal_streamoff+0x35/0x90 [videobuf2_core]
  [<f925fac5>] vb2_streamoff+0x35/0x60 [videobuf2_core]
  [<f925fb27>] vb2_ioctl_streamoff+0x37/0x40 [videobuf2_core]
  [<f8e45895>] v4l_streamoff+0x15/0x20 [videodev]
  [<f8e4925d>] __video_do_ioctl+0x23d/0x2d0 [videodev]
  [<f8e49020>] ? video_ioctl2+0x20/0x20 [videodev]
  [<f8e48c63>] video_usercopy+0x203/0x5a0 [videodev]
  [<f8e49020>] ? video_ioctl2+0x20/0x20 [videodev]
  [<c039d0e7>] ? fsnotify+0x1e7/0x2b0
  [<f8e49012>] video_ioctl2+0x12/0x20 [videodev]
  [<f8e49020>] ? video_ioctl2+0x20/0x20 [videodev]
  [<f8e4461e>] v4l2_ioctl+0xee/0x130 [videodev]
  [<f8e44530>] ? v4l2_open+0xf0/0xf0 [videodev]
  [<c0378de2>] do_vfs_ioctl+0x2e2/0x4d0
  [<c0368eec>] ? vfs_write+0x13c/0x1c0
  [<c0369a8f>] ? vfs_writev+0x2f/0x50
  [<c0379028>] SyS_ioctl+0x58/0x80
  [<c076fff3>] sysenter_do_call+0x12/0x12
 ---[ end trace 5545f934409f13f4 ]---
...

Many thanks to Hans Verkuil, whose recently added check in the vb2 core unveiled
this long standing issue and who has investigated it further.

Signed-off-by: Frank Schäfer <fschaefer.oss at googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab at samsung.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/media/usb/em28xx/em28xx-video.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c
index dd19c9f..f435c75 100644
--- a/drivers/media/usb/em28xx/em28xx-video.c
+++ b/drivers/media/usb/em28xx/em28xx-video.c
@@ -696,13 +696,16 @@ static int em28xx_stop_streaming(struct vb2_queue *vq)
 	}

 	spin_lock_irqsave(&dev->slock, flags);
+	if (dev->usb_ctl.vid_buf != NULL) {
+		vb2_buffer_done(&dev->usb_ctl.vid_buf->vb, VB2_BUF_STATE_ERROR);
+		dev->usb_ctl.vid_buf = NULL;
+	}
 	while (!list_empty(&vidq->active)) {
 		struct em28xx_buffer *buf;
 		buf = list_entry(vidq->active.next, struct em28xx_buffer, list);
 		list_del(&buf->list);
 		vb2_buffer_done(&buf->vb, VB2_BUF_STATE_ERROR);
 	}
-	dev->usb_ctl.vid_buf = NULL;
 	spin_unlock_irqrestore(&dev->slock, flags);

 	return 0;
@@ -724,13 +727,16 @@ int em28xx_stop_vbi_streaming(struct vb2_queue *vq)
 	}

 	spin_lock_irqsave(&dev->slock, flags);
+	if (dev->usb_ctl.vbi_buf != NULL) {
+		vb2_buffer_done(&dev->usb_ctl.vbi_buf->vb, VB2_BUF_STATE_ERROR);
+		dev->usb_ctl.vbi_buf = NULL;
+	}
 	while (!list_empty(&vbiq->active)) {
 		struct em28xx_buffer *buf;
 		buf = list_entry(vbiq->active.next, struct em28xx_buffer, list);
 		list_del(&buf->list);
 		vb2_buffer_done(&buf->vb, VB2_BUF_STATE_ERROR);
 	}
-	dev->usb_ctl.vbi_buf = NULL;
 	spin_unlock_irqrestore(&dev->slock, flags);

 	return 0;
--
1.9.1