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path: root/drivers/media/video/v4l2-dev.c
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Diffstat (limited to 'drivers/media/video/v4l2-dev.c')
-rw-r--r--drivers/media/video/v4l2-dev.c153
1 files changed, 100 insertions, 53 deletions
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index cb77197d480e..359e23290a7e 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -25,7 +25,6 @@
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/slab.h>
-#include <linux/smp_lock.h>
#include <asm/uaccess.h>
#include <asm/system.h>
@@ -81,7 +80,7 @@ static inline unsigned long *devnode_bits(int vfl_type)
/* Any types not assigned to fixed minor ranges must be mapped to
one single bitmap for the purposes of finding a free node number
since all those unassigned types use the same minor range. */
- int idx = (vfl_type > VFL_TYPE_VTX) ? VFL_TYPE_MAX - 1 : vfl_type;
+ int idx = (vfl_type > VFL_TYPE_RADIO) ? VFL_TYPE_MAX - 1 : vfl_type;
return devnode_nums[idx];
}
@@ -187,79 +186,117 @@ static ssize_t v4l2_read(struct file *filp, char __user *buf,
size_t sz, loff_t *off)
{
struct video_device *vdev = video_devdata(filp);
+ int ret = -ENODEV;
if (!vdev->fops->read)
return -EINVAL;
- if (!video_is_registered(vdev))
- return -EIO;
- return vdev->fops->read(filp, buf, sz, off);
+ if (vdev->lock && mutex_lock_interruptible(vdev->lock))
+ return -ERESTARTSYS;
+ if (video_is_registered(vdev))
+ ret = vdev->fops->read(filp, buf, sz, off);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ return ret;
}
static ssize_t v4l2_write(struct file *filp, const char __user *buf,
size_t sz, loff_t *off)
{
struct video_device *vdev = video_devdata(filp);
+ int ret = -ENODEV;
if (!vdev->fops->write)
return -EINVAL;
- if (!video_is_registered(vdev))
- return -EIO;
- return vdev->fops->write(filp, buf, sz, off);
+ if (vdev->lock && mutex_lock_interruptible(vdev->lock))
+ return -ERESTARTSYS;
+ if (video_is_registered(vdev))
+ ret = vdev->fops->write(filp, buf, sz, off);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ return ret;
}
static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
{
struct video_device *vdev = video_devdata(filp);
+ int ret = POLLERR | POLLHUP;
- if (!vdev->fops->poll || !video_is_registered(vdev))
+ if (!vdev->fops->poll)
return DEFAULT_POLLMASK;
- return vdev->fops->poll(filp, poll);
+ if (vdev->lock)
+ mutex_lock(vdev->lock);
+ if (video_is_registered(vdev))
+ ret = vdev->fops->poll(filp, poll);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ return ret;
}
static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct video_device *vdev = video_devdata(filp);
- int ret;
+ int ret = -ENODEV;
- /* Allow ioctl to continue even if the device was unregistered.
- Things like dequeueing buffers might still be useful. */
if (vdev->fops->unlocked_ioctl) {
- ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
+ if (vdev->lock && mutex_lock_interruptible(vdev->lock))
+ return -ERESTARTSYS;
+ if (video_is_registered(vdev))
+ ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
} else if (vdev->fops->ioctl) {
- /* TODO: convert all drivers to unlocked_ioctl */
- lock_kernel();
- ret = vdev->fops->ioctl(filp, cmd, arg);
- unlock_kernel();
+ /* This code path is a replacement for the BKL. It is a major
+ * hack but it will have to do for those drivers that are not
+ * yet converted to use unlocked_ioctl.
+ *
+ * There are two options: if the driver implements struct
+ * v4l2_device, then the lock defined there is used to
+ * serialize the ioctls. Otherwise the v4l2 core lock defined
+ * below is used. This lock is really bad since it serializes
+ * completely independent devices.
+ *
+ * Both variants suffer from the same problem: if the driver
+ * sleeps, then it blocks all ioctls since the lock is still
+ * held. This is very common for VIDIOC_DQBUF since that
+ * normally waits for a frame to arrive. As a result any other
+ * ioctl calls will proceed very, very slowly since each call
+ * will have to wait for the VIDIOC_QBUF to finish. Things that
+ * should take 0.01s may now take 10-20 seconds.
+ *
+ * The workaround is to *not* take the lock for VIDIOC_DQBUF.
+ * This actually works OK for videobuf-based drivers, since
+ * videobuf will take its own internal lock.
+ */
+ static DEFINE_MUTEX(v4l2_ioctl_mutex);
+ struct mutex *m = vdev->v4l2_dev ?
+ &vdev->v4l2_dev->ioctl_lock : &v4l2_ioctl_mutex;
+
+ if (cmd != VIDIOC_DQBUF && mutex_lock_interruptible(m))
+ return -ERESTARTSYS;
+ if (video_is_registered(vdev))
+ ret = vdev->fops->ioctl(filp, cmd, arg);
+ if (cmd != VIDIOC_DQBUF)
+ mutex_unlock(m);
} else
ret = -ENOTTY;
return ret;
}
-#ifdef CONFIG_MMU
-#define v4l2_get_unmapped_area NULL
-#else
-static unsigned long v4l2_get_unmapped_area(struct file *filp,
- unsigned long addr, unsigned long len, unsigned long pgoff,
- unsigned long flags)
-{
- struct video_device *vdev = video_devdata(filp);
-
- if (!vdev->fops->get_unmapped_area)
- return -ENOSYS;
- if (!video_is_registered(vdev))
- return -ENODEV;
- return vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags);
-}
-#endif
-
static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
{
struct video_device *vdev = video_devdata(filp);
+ int ret = -ENODEV;
- if (!vdev->fops->mmap || !video_is_registered(vdev))
- return -ENODEV;
- return vdev->fops->mmap(filp, vm);
+ if (!vdev->fops->mmap)
+ return ret;
+ if (vdev->lock && mutex_lock_interruptible(vdev->lock))
+ return -ERESTARTSYS;
+ if (video_is_registered(vdev))
+ ret = vdev->fops->mmap(filp, vm);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ return ret;
}
/* Override for the open function */
@@ -271,8 +308,7 @@ static int v4l2_open(struct inode *inode, struct file *filp)
/* Check if the video device is available */
mutex_lock(&videodev_lock);
vdev = video_devdata(filp);
- /* return ENODEV if the video device has been removed
- already or if it is not registered anymore. */
+ /* return ENODEV if the video device has already been removed. */
if (vdev == NULL || !video_is_registered(vdev)) {
mutex_unlock(&videodev_lock);
return -ENODEV;
@@ -280,9 +316,20 @@ static int v4l2_open(struct inode *inode, struct file *filp)
/* and increase the device refcount */
video_get(vdev);
mutex_unlock(&videodev_lock);
- if (vdev->fops->open)
- ret = vdev->fops->open(filp);
+ if (vdev->fops->open) {
+ if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
+ ret = -ERESTARTSYS;
+ goto err;
+ }
+ if (video_is_registered(vdev))
+ ret = vdev->fops->open(filp);
+ else
+ ret = -ENODEV;
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ }
+err:
/* decrease the refcount in case of an error */
if (ret)
video_put(vdev);
@@ -295,8 +342,13 @@ static int v4l2_release(struct inode *inode, struct file *filp)
struct video_device *vdev = video_devdata(filp);
int ret = 0;
- if (vdev->fops->release)
+ if (vdev->fops->release) {
+ if (vdev->lock)
+ mutex_lock(vdev->lock);
vdev->fops->release(filp);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ }
/* decrease the refcount unconditionally since the release()
return value is ignored. */
@@ -309,7 +361,6 @@ static const struct file_operations v4l2_fops = {
.read = v4l2_read,
.write = v4l2_write,
.open = v4l2_open,
- .get_unmapped_area = v4l2_get_unmapped_area,
.mmap = v4l2_mmap,
.unlocked_ioctl = v4l2_ioctl,
#ifdef CONFIG_COMPAT
@@ -377,8 +428,6 @@ static int get_index(struct video_device *vdev)
*
* %VFL_TYPE_GRABBER - A frame grabber
*
- * %VFL_TYPE_VTX - A teletext device
- *
* %VFL_TYPE_VBI - Vertical blank data (undecoded)
*
* %VFL_TYPE_RADIO - A radio card
@@ -411,9 +460,6 @@ static int __video_register_device(struct video_device *vdev, int type, int nr,
case VFL_TYPE_GRABBER:
name_base = "video";
break;
- case VFL_TYPE_VTX:
- name_base = "vtx";
- break;
case VFL_TYPE_VBI:
name_base = "vbi";
break;
@@ -451,10 +497,6 @@ static int __video_register_device(struct video_device *vdev, int type, int nr,
minor_offset = 64;
minor_cnt = 64;
break;
- case VFL_TYPE_VTX:
- minor_offset = 192;
- minor_cnt = 32;
- break;
case VFL_TYPE_VBI:
minor_offset = 224;
minor_cnt = 32;
@@ -582,7 +624,12 @@ void video_unregister_device(struct video_device *vdev)
if (!vdev || !video_is_registered(vdev))
return;
+ mutex_lock(&videodev_lock);
+ /* This must be in a critical section to prevent a race with v4l2_open.
+ * Once this bit has been cleared video_get may never be called again.
+ */
clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
+ mutex_unlock(&videodev_lock);
device_unregister(&vdev->dev);
}
EXPORT_SYMBOL(video_unregister_device);
generated by cgit v1.2.3 (git 2.39.1) at 2025-12-13 23:14:44 +0000