[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>

diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 03f7f46..bfd392e 100644 (file)
--- 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);