[media] v4l2-dev: use mutex_lock_interruptible instead of plain mutex_lock

Where reasonable use mutex_lock_interruptible instead of mutex_lock.
Also fix the poll, read and write error codes when called with an unregistered
device (e.g. after a USB device was disconnected). Poll must return
POLLERR|POLLHUP and read/write must return -ENODEV.

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

1 files changed, 17 insertions, 14 deletions

diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 03f7f4670e9b..bfd392e2436d 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -186,12 +186,12 @@ 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 = -EIO;
+        int ret = -ENODEV;
 
         if (!vdev->fops->read)
                 return -EINVAL;
-        if (vdev->lock)
-                mutex_lock(vdev->lock);
+        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)
@@ -203,12 +203,12 @@ 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 = -EIO;
+        int ret = -ENODEV;
 
         if (!vdev->fops->write)
                 return -EINVAL;
-        if (vdev->lock)
-                mutex_lock(vdev->lock);
+        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)
@@ -219,10 +219,10 @@ static ssize_t v4l2_write(struct file *filp, const char __user *buf,
 static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
 {
         struct video_device *vdev = video_devdata(filp);
-        int ret = DEFAULT_POLLMASK;
+        int ret = POLLERR | POLLHUP;
 
         if (!vdev->fops->poll)
-                return ret;
+                return DEFAULT_POLLMASK;
         if (vdev->lock)
                 mutex_lock(vdev->lock);
         if (video_is_registered(vdev))
@@ -238,8 +238,8 @@ static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
         int ret = -ENODEV;
 
         if (vdev->fops->unlocked_ioctl) {
-                if (vdev->lock)
-                        mutex_lock(vdev->lock);
+                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)
@@ -265,8 +265,8 @@ static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
 
         if (!vdev->fops->mmap)
                 return ret;
-        if (vdev->lock)
-                mutex_lock(vdev->lock);
+        if (vdev->lock && mutex_lock_interruptible(vdev->lock))
+                return -ERESTARTSYS;
         if (video_is_registered(vdev))
                 ret = vdev->fops->mmap(filp, vm);
         if (vdev->lock)
@@ -292,8 +292,10 @@ 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(vdev->lock);
+                if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
+                        ret = -ERESTARTSYS;
+                        goto err;
+                }
                 if (video_is_registered(vdev))
                         ret = vdev->fops->open(filp);
                 else
@@ -302,6 +304,7 @@ static int v4l2_open(struct inode *inode, struct file *filp)
                         mutex_unlock(vdev->lock);
         }
 
+err:
         /* decrease the refcount in case of an error */
         if (ret)
                 video_put(vdev);