V4L/DVB (12725): v4l: warn when desired devnodenr is in use & add _no_warn function

Warn when the desired device node number is already in use, except when
the new video_register_device_no_warn function is called since in some
use-cases that warning is not relevant.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 19 insertions, 1 deletions

diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 4715f08157bc..500cbe9891ac 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -382,6 +382,8 @@ static int get_index(struct video_device *vdev)
  *      @type: type of device to register
  *      @nr:   which device node number (0 == /dev/video0, 1 == /dev/video1, ...
  *             -1 == first free)
+ *      @warn_if_nr_in_use: warn if the desired device node number
+ *             was already in use and another number was chosen instead.
  *
  *      The registration code assigns minor numbers and device node numbers
  *      based on the requested type and registers the new device node with
@@ -401,7 +403,8 @@ static int get_index(struct video_device *vdev)
  *
  *      %VFL_TYPE_RADIO - A radio card
  */
-int video_register_device(struct video_device *vdev, int type, int nr)
+static int __video_register_device(struct video_device *vdev, int type, int nr,
+                int warn_if_nr_in_use)
 {
         int i = 0;
         int ret;
@@ -547,6 +550,10 @@ int video_register_device(struct video_device *vdev, int type, int nr)
            reference to the device goes away. */
         vdev->dev.release = v4l2_device_release;
 
+        if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
+                printk(KERN_WARNING "%s: requested %s%d, got %s%d\n",
+                                __func__, name_base, nr, name_base, vdev->num);
+
         /* Part 5: Activate this minor. The char device can now be used. */
         mutex_lock(&videodev_lock);
         video_device[vdev->minor] = vdev;
@@ -563,8 +570,19 @@ cleanup:
         vdev->minor = -1;
         return ret;
 }
+
+int video_register_device(struct video_device *vdev, int type, int nr)
+{
+        return __video_register_device(vdev, type, nr, 1);
+}
 EXPORT_SYMBOL(video_register_device);
 
+int video_register_device_no_warn(struct video_device *vdev, int type, int nr)
+{
+        return __video_register_device(vdev, type, nr, 0);
+}
+EXPORT_SYMBOL(video_register_device_no_warn);
+
 /**
  *      video_unregister_device - unregister a video4linux device
  *      @vdev: the device to unregister