diff options
Diffstat (limited to 'drivers/media/v4l2-core/v4l2-dev.c')
| -rw-r--r-- | drivers/media/v4l2-core/v4l2-dev.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c index 8be561ab2615..206cff6b0c97 100644 --- a/drivers/media/v4l2-core/v4l2-dev.c +++ b/drivers/media/v4l2-core/v4l2-dev.c @@ -360,6 +360,34 @@ static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) ret = vdev->fops->unlocked_ioctl(filp, cmd, arg); if (lock) mutex_unlock(lock); + } else if (vdev->fops->ioctl) { + /* 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. + * + * All drivers implement struct v4l2_device, so we use the + * lock defined there to serialize the ioctls. + * + * However, 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. + */ + struct mutex *m = &vdev->v4l2_dev->ioctl_lock; + + 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; @@ -567,6 +595,7 @@ static void determine_valid_ioctls(struct video_device *vdev) set_bit(_IOC_NR(VIDIOC_DBG_G_REGISTER), valid_ioctls); set_bit(_IOC_NR(VIDIOC_DBG_S_REGISTER), valid_ioctls); #endif + SET_VALID_IOCTL(ops, VIDIOC_DBG_G_CHIP_IDENT, vidioc_g_chip_ident); /* yes, really vidioc_subscribe_event */ SET_VALID_IOCTL(ops, VIDIOC_DQEVENT, vidioc_subscribe_event); SET_VALID_IOCTL(ops, VIDIOC_SUBSCRIBE_EVENT, vidioc_subscribe_event); |