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[media] v4l2-device: check if already unregistered

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It was possible to unregister an already unregistered v4l2_device struct.
Add a check whether that already happened and just return if that was
the case.
Also refuse to register a v4l2_device if both the dev and name fields are
empty. A warning was already produced in that case, but since the name field
is now used to detect whether or not the v4l2_device was already unregistered
this particular combination should be rejected.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans Verkuil 2013-06-12 06:04:04 -03:00 committed by Mauro Carvalho Chehab
parent 7feeb14821
commit 9e882e3bc9
1 changed files with 7 additions and 2 deletions
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9
drivers/media/v4l2-core/v4l2-device.c
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@ -44,7 +44,8 @@ int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
v4l2_dev->dev = dev; v4l2_dev->dev = dev;
if (dev == NULL) { if (dev == NULL) {
/* If dev == NULL, then name must be filled in by the caller */ /* If dev == NULL, then name must be filled in by the caller */
WARN_ON(!v4l2_dev->name[0]); if (WARN_ON(!v4l2_dev->name[0]))
return -EINVAL;
return 0; return 0;
} }
@ -105,7 +106,9 @@ void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
{ {
struct v4l2_subdev *sd, *next; struct v4l2_subdev *sd, *next;
if (v4l2_dev == NULL) /* Just return if v4l2_dev is NULL or if it was already
* unregistered before. */
if (v4l2_dev == NULL || !v4l2_dev->name[0])
return; return;
v4l2_device_disconnect(v4l2_dev); v4l2_device_disconnect(v4l2_dev);
@ -135,6 +138,8 @@ void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
} }
#endif #endif
} }
/* Mark as unregistered, thus preventing duplicate unregistrations */
v4l2_dev->name[0] = '\0';
} }
EXPORT_SYMBOL_GPL(v4l2_device_unregister); EXPORT_SYMBOL_GPL(v4l2_device_unregister);