linux-kernel - mmotm 2010-10-13 - GSPCA SPCA561 webcam driver broken

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Date:	Thu, 14 Oct 2010 16:06:29 -0400
From:	Valdis.Kletnieks@...edu
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Hans Verkuil <hverkuil@...all.nl>,
	Mauro Carvalho Chehab <mchehab@...hat.com>
Cc:	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org
Subject: mmotm 2010-10-13 - GSPCA SPCA561 webcam driver broken

On Wed, 13 Oct 2010 17:13:25 PDT, akpm@...ux-foundation.org said:
> The mm-of-the-moment snapshot 2010-10-13-17-13 has been uploaded to
> 
>    http://userweb.kernel.org/~akpm/mmotm/

This broke my webcam.  I bisected it down to this commit, and things
work again after reverting the 2 code lines of change.

commit 9e4d79a98ebd857ec729f5fa8f432f35def4d0da
Author: Hans Verkuil <hverkuil@...all.nl>
Date:   Sun Sep 26 08:16:56 2010 -0300

    V4L/DVB: v4l2-dev: after a disconnect any ioctl call will be blocked
    
    Until now all fops except release and (unlocked_)ioctl returned an error
    after the device node was unregistered. Extend this as well to the ioctl
    fops. There is nothing useful that an application can do here and it
    complicates the driver code unnecessarily.
    
    Signed-off-by: Hans Verkuil <hverkuil@...all.nl>
    Signed-off-by: Mauro Carvalho Chehab <mchehab@...hat.com>


diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index d4a3532..f069c61 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -221,8 +221,8 @@ static long v4l2_ioctl(struct file *filp, unsigned int cmd, 
        struct video_device *vdev = video_devdata(filp);
        int ret;
 
-       /* Allow ioctl to continue even if the device was unregistered.
-          Things like dequeueing buffers might still be useful. */
+       if (!vdev->fops->ioctl)
+               return -ENOTTY;
        if (vdev->fops->unlocked_ioctl) {
                ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
        } else if (vdev->fops->ioctl) {

I suspect this doesn't do what's intended if a driver is using ->unlocked_ioctl
rather than ->ioctl, and it should be reverted - it only saves at most one
if statement.


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