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SubjectRe: [PATCH 12/13][Resubmit][drivers/media] changed ioctls to unlocked
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Hello, Stoyan

On Tue, 2009-03-24 at 16:38 -0500, stoyboyker@gmail.com wrote:
> From: Stoyan Gaydarov <stoyboyker@gmail.com>
>
> Signed-off-by: Stoyan Gaydarov <stoyboyker@gmail.com>
> ---
> drivers/media/dvb/bt8xx/dst_ca.c | 7 +++++--
> drivers/media/video/dabusb.c | 11 ++++++++---
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/dvb/bt8xx/dst_ca.c b/drivers/media/dvb/bt8xx/dst_ca.c
> index 0258451..d3487c5 100644
> --- a/drivers/media/dvb/bt8xx/dst_ca.c
> +++ b/drivers/media/dvb/bt8xx/dst_ca.c
> @@ -552,8 +552,10 @@ free_mem_and_exit:
> return result;
> }
>
> -static int dst_ca_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long ioctl_arg)
> +static long dst_ca_ioctl(struct file *file, unsigned int cmd, unsigned long ioctl_arg)
> {
> + lock_kernel();
> +
> struct dvb_device* dvbdev = (struct dvb_device*) file->private_data;
> struct dst_state* state = (struct dst_state*) dvbdev->priv;
> struct ca_slot_info *p_ca_slot_info;
> @@ -647,6 +649,7 @@ static int dst_ca_ioctl(struct inode *inode, struct file *file, unsigned int cmd
> kfree (p_ca_slot_info);
> kfree (p_ca_caps);
>
> + unlock_kernel();
> return result;
> }
>
> @@ -684,7 +687,7 @@ static ssize_t dst_ca_write(struct file *file, const char __user *buffer, size_t
>
> static struct file_operations dst_ca_fops = {
> .owner = THIS_MODULE,
> - .ioctl = dst_ca_ioctl,
> + .unlocked_ioctl = dst_ca_ioctl,
> .open = dst_ca_open,
> .release = dst_ca_release,
> .read = dst_ca_read,
> diff --git a/drivers/media/video/dabusb.c b/drivers/media/video/dabusb.c
> index 298810d..c31e76f 100644
> --- a/drivers/media/video/dabusb.c
> +++ b/drivers/media/video/dabusb.c
> @@ -657,22 +657,26 @@ static int dabusb_release (struct inode *inode, struct file *file)
> return 0;
> }
>
> -static int dabusb_ioctl (struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
> +static long dabusb_ioctl (struct file *file, unsigned int cmd, unsigned long arg)
> {
> pdabusb_t s = (pdabusb_t) file->private_data;
> pbulk_transfer_t pbulk;
> int ret = 0;
> int version = DABUSB_VERSION;
>
> + lock_kernel();
> dbg("dabusb_ioctl");
>
> - if (s->remove_pending)
> + if (s->remove_pending) {
> + unlock_kernel();
> return -EIO;
> + }
>
> mutex_lock(&s->mutex);
>
> if (!s->usbdev) {
> mutex_unlock(&s->mutex);
> + unlock_kernel();
> return -EIO;
> }
>
> @@ -713,6 +717,7 @@ static int dabusb_ioctl (struct inode *inode, struct file *file, unsigned int cm
> break;
> }
> mutex_unlock(&s->mutex);
> + unlock_kernel();

May i ask why big kernel lock is used here?
Where is an advantage of BKL here?
Why not to use, for example, one more mutex lock?

--
Best regards, Klimov Alexey



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