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[media] uvc gadget: switch to v4l2 core locking

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Switch this driver over to the V4L2 core locking mechanism in preparation
for switching to unlocked_ioctl. Suggested by Laurent Pinchart.

This patch introduces a new mutex at the struct uvc_video level and
drops the old mutex at the queue level. The new lock is now used for all
ioctl locking and in the release file operation (the driver always has
to take care of locking in file operations, the core only serializes
ioctls).

Note that the mmap and get_unmapped_area file operations no longer take
a lock. Commit f035eb4e97 fixed a AB-BA
deadlock by moving all the locking down into vb2, so the mmap and
get_unmapped_area file operations should no longer do any locking before
calling into vb2.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This commit is contained in:
Hans Verkuil
2015-02-17 05:44:06 -03:00
committed by Mauro Carvalho Chehab
parent 2e1328dd5a
commit d8e96c4bf6
6 changed files with 22 additions and 70 deletions
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2
drivers/usb/gadget/function/f_uvc.c
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@@ -447,6 +447,7 @@ uvc_register_video(struct uvc_device *uvc)
video->ioctl_ops = &uvc_v4l2_ioctl_ops;
video->release = video_device_release;
video->vfl_dir = VFL_DIR_TX;
video->lock = &uvc->video.mutex;
strlcpy(video->name, cdev->gadget->name, sizeof(video->name));
uvc->vdev = video;
@@ -918,6 +919,7 @@ static struct usb_function *uvc_alloc(struct usb_function_instance *fi)
if (uvc == NULL)
return ERR_PTR(-ENOMEM);
mutex_init(&uvc->video.mutex);
uvc->state = UVC_STATE_DISCONNECTED;
opts = fi_to_f_uvc_opts(fi);