Just like with some ioctls some drivers may want to prevent the core from
taking the V4L2 core lock on other fops.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Documentation/video4linux/v4l2-framework.txt | 7 ++--
drivers/media/video/v4l2-dev.c | 45 ++++++++++++++------------
include/media/v4l2-dev.h | 4 +++
3 files changed, 34 insertions(+), 22 deletions(-)
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 4b9b407..c2e6591 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -621,8 +621,11 @@ v4l2_file_operations and locking
You can set a pointer to a mutex_lock in struct video_device. Usually this
will be either a top-level mutex or a mutex per device node. By default this
-lock will be used for each file operation and ioctl, but you can disable
-locking for selected ioctls by calling:
+lock will be used for each file operation and ioctl, you can disable this
+for all non ioctl operations by setting the V4L2_FL_DONT_USE_LOCK flag, e.g.:
+ set_bit(V4L2_FL_DONT_USE_LOCK, &vdev->flags);
+
+For ioctls you can disable locking for selected ioctls by calling:
void v4l2_dont_use_lock(struct video_device *vdev, unsigned int cmd);
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index a51a061..eb20f0b 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -274,12 +274,12 @@ static ssize_t v4l2_read(struct file *filp, char __user *buf,
if (!vdev->fops->read)
return -EINVAL;
- if (vdev->lock && mutex_lock_interruptible(vdev->lock))
+ if (vdev->fops_lock && mutex_lock_interruptible(vdev->fops_lock))
return -ERESTARTSYS;
if (video_is_registered(vdev))
ret = vdev->fops->read(filp, buf, sz, off);
- if (vdev->lock)
- mutex_unlock(vdev->lock);
+ if (vdev->fops_lock)
+ mutex_unlock(vdev->fops_lock);
return ret;
}
@@ -291,12 +291,12 @@ static ssize_t v4l2_write(struct file *filp, const char __user *buf,
if (!vdev->fops->write)
return -EINVAL;
- if (vdev->lock && mutex_lock_interruptible(vdev->lock))
+ if (vdev->fops_lock && mutex_lock_interruptible(vdev->fops_lock))
return -ERESTARTSYS;
if (video_is_registered(vdev))
ret = vdev->fops->write(filp, buf, sz, off);
- if (vdev->lock)
- mutex_unlock(vdev->lock);
+ if (vdev->fops_lock)
+ mutex_unlock(vdev->fops_lock);
return ret;
}
@@ -307,12 +307,12 @@ static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
if (!vdev->fops->poll)
return DEFAULT_POLLMASK;
- if (vdev->lock)
- mutex_lock(vdev->lock);
+ if (vdev->fops_lock)
+ mutex_lock(vdev->fops_lock);
if (video_is_registered(vdev))
ret = vdev->fops->poll(filp, poll);
- if (vdev->lock)
- mutex_unlock(vdev->lock);
+ if (vdev->fops_lock)
+ mutex_unlock(vdev->fops_lock);
return ret;
}
@@ -399,12 +399,12 @@ static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
if (!vdev->fops->mmap)
return ret;
- if (vdev->lock && mutex_lock_interruptible(vdev->lock))
+ if (vdev->fops_lock && mutex_lock_interruptible(vdev->fops_lock))
return -ERESTARTSYS;
if (video_is_registered(vdev))
ret = vdev->fops->mmap(filp, vm);
- if (vdev->lock)
- mutex_unlock(vdev->lock);
+ if (vdev->fops_lock)
+ mutex_unlock(vdev->fops_lock);
return ret;
}
@@ -426,7 +426,8 @@ static int v4l2_open(struct inode *inode, struct file *filp)
video_get(vdev);
mutex_unlock(&videodev_lock);
if (vdev->fops->open) {
- if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
+ if (vdev->fops_lock &&
+ mutex_lock_interruptible(vdev->fops_lock)) {
ret = -ERESTARTSYS;
goto err;
}
@@ -434,8 +435,8 @@ static int v4l2_open(struct inode *inode, struct file *filp)
ret = vdev->fops->open(filp);
else
ret = -ENODEV;
- if (vdev->lock)
- mutex_unlock(vdev->lock);
+ if (vdev->fops_lock)
+ mutex_unlock(vdev->fops_lock);
}
err:
@@ -452,11 +453,11 @@ static int v4l2_release(struct inode *inode, struct file *filp)
int ret = 0;
if (vdev->fops->release) {
- if (vdev->lock)
- mutex_lock(vdev->lock);
+ if (vdev->fops_lock)
+ mutex_lock(vdev->fops_lock);
vdev->fops->release(filp);
- if (vdev->lock)
- mutex_unlock(vdev->lock);
+ if (vdev->fops_lock)
+ mutex_unlock(vdev->fops_lock);
}
/* decrease the refcount unconditionally since the release()
return value is ignored. */
@@ -601,6 +602,10 @@ int __video_register_device(struct video_device *vdev, int type, int nr,
if (vdev->prio == NULL)
vdev->prio = &vdev->v4l2_dev->prio;
}
+ if (test_bit(V4L2_FL_DONT_USE_LOCK, &vdev->flags))
+ vdev->fops_lock = NULL;
+ else
+ vdev->fops_lock = vdev->lock;
/* Part 2: find a free minor, device node number and device index. */
#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index 0da84dc..fa80124 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -39,6 +39,9 @@ struct v4l2_ctrl_handler;
#define V4L2_FL_USES_V4L2_FH (1)
/* Use the prio field of v4l2_fh for core priority checking */
#define V4L2_FL_USE_FH_PRIO (2)
+/* Don't take the lock for all fops, except ioctl. For ioctls the lock can be
+ disabled on a per ioctl basis by calling v4l2_dont_use_lock. */
+#define V4L2_FL_DONT_USE_LOCK (3)
/* Priority helper functions */
@@ -130,6 +133,7 @@ struct video_device
/* serialization lock */
DECLARE_BITMAP(dont_use_lock, BASE_VIDIOC_PRIVATE);
struct mutex *lock;
+ struct mutex *fops_lock; /* Internal v4l2-vdev usage only */
};
#define media_entity_to_video_device(__e) \
--
1.7.10
--
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