Hi Hans, On Thursday 01 April 2010 10:01:10 Hans Verkuil wrote: > Hi all, > > I just read on LWN that the core kernel guys are putting more effort into > removing the BKL. We are still using it in our own drivers, mostly V4L. > > I added a BKL column to my driver list: > > http://www.linuxtv.org/wiki/index.php/V4L_framework_progress#Bridge_Drivers > > If you 'own' one of these drivers that still use BKL, then it would be nice > if you can try and remove the use of the BKL from those drivers. > > The other part that needs to be done is to move from using the .ioctl file > op to using .unlocked_ioctl. Very few drivers do that, but I suspect > almost no driver actually needs to use .ioctl. What about something like this patch as a first step ? diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c index 7090699..14e1b1c 100644 --- a/drivers/media/video/v4l2-dev.c +++ b/drivers/media/video/v4l2-dev.c @@ -25,6 +25,7 @@ #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> @@ -215,28 +216,22 @@ static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll) return vdev->fops->poll(filp, poll); } -static int v4l2_ioctl(struct inode *inode, struct file *filp, - unsigned int cmd, unsigned long arg) -{ - struct video_device *vdev = video_devdata(filp); - - if (!vdev->fops->ioctl) - return -ENOTTY; - /* Allow ioctl to continue even if the device was unregistered. - Things like dequeueing buffers might still be useful. */ - return vdev->fops->ioctl(filp, cmd, arg); -} - static long v4l2_unlocked_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { struct video_device *vdev = video_devdata(filp); + int ret = -ENOTTY; - if (!vdev->fops->unlocked_ioctl) - return -ENOTTY; /* Allow ioctl to continue even if the device was unregistered. Things like dequeueing buffers might still be useful. */ - return vdev->fops->unlocked_ioctl(filp, cmd, arg); + if (vdev->fops->ioctl) { + lock_kernel(); + ret = vdev->fops->ioctl(filp, cmd, arg); + unlock_kernel(); + } else if (vdev->fops->unlocked_ioctl) + ret = vdev->fops->unlocked_ioctl(filp, cmd, arg); + + return ret; } #ifdef CONFIG_MMU @@ -323,22 +318,6 @@ static const struct file_operations v4l2_unlocked_fops = { .llseek = no_llseek, }; -static const struct file_operations v4l2_fops = { - .owner = THIS_MODULE, - .read = v4l2_read, - .write = v4l2_write, - .open = v4l2_open, - .get_unmapped_area = v4l2_get_unmapped_area, - .mmap = v4l2_mmap, - .ioctl = v4l2_ioctl, -#ifdef CONFIG_COMPAT - .compat_ioctl = v4l2_compat_ioctl32, -#endif - .release = v4l2_release, - .poll = v4l2_poll, - .llseek = no_llseek, -}; - /** * get_index - assign stream index number based on parent device * @vdev: video_device to assign index number to, vdev->parent should be assigned @@ -517,10 +496,7 @@ static int __video_register_device(struct video_device *vdev, int type, int nr, ret = -ENOMEM; goto cleanup; } - if (vdev->fops->unlocked_ioctl) - vdev->cdev->ops = &v4l2_unlocked_fops; - else - vdev->cdev->ops = &v4l2_fops; + vdev->cdev->ops = &v4l2_unlocked_fops; vdev->cdev->owner = vdev->fops->owner; ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1); if (ret < 0) { A second step would be to replace lock_kernel/unlock_kernel with a V4L-specific lock, and the third step to push the lock into drivers. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
