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Date: Thu, 22 May 2008 22:08:04 -0400
From: Andy Walls <awalls@...ix.net>
To: Alan Cox <alan@...rguk.ukuu.org.uk>, video4linux-list@...hat.com
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] video4linux: Push down the BKL
On Thu, 2008-05-22 at 22:37 +0100, Alan Cox wrote:
> For most drivers the generic ioctl handler does the work and we update it
> and it becomes the unlocked_ioctl method. Older drivers use the usercopy
> method so we make it do the work. Finally there are a few special cases.
>
> Signed-off-by: Alan Cox <alan@...hat.com>
I'd like to start planning out the changes to eliminate the BKL from
cx18.
Could someone give me a brief education as to what elements of
cx18/ivtv_v4l2_do_ioctl() would be forcing the use of the BKL for these
drivers' ioctls? I'm assuming it's not the
mutex_un/lock(&....->serialize_lock) and that the answer's not in the
diff.
Thanks.
Andy
> diff --git a/drivers/media/video/cx18/cx18-ioctl.c b/drivers/media/video/cx18/cx18-ioctl.c
> index dbdcb86..faf3a31 100644
> --- a/drivers/media/video/cx18/cx18-ioctl.c
> +++ b/drivers/media/video/cx18/cx18-ioctl.c
> @@ -837,15 +837,16 @@ static int cx18_v4l2_do_ioctl(struct inode *inode, struct file *filp,
> return 0;
> }
>
> -int cx18_v4l2_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
> - unsigned long arg)
> +long cx18_v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> struct cx18_open_id *id = (struct cx18_open_id *)filp->private_data;
> struct cx18 *cx = id->cx;
> int res;
>
> + lock_kernel();
> mutex_lock(&cx->serialize_lock);
> - res = video_usercopy(inode, filp, cmd, arg, cx18_v4l2_do_ioctl);
> + res = video_usercopy(filp, cmd, arg, cx18_v4l2_do_ioctl);
> mutex_unlock(&cx->serialize_lock);
> + unlock_kernel();
> return res;
> }
> diff --git a/drivers/media/video/cx18/cx18-ioctl.h b/drivers/media/video/cx18/cx18-ioctl.h
> index 9f4c7eb..32bede3 100644
> --- a/drivers/media/video/cx18/cx18-ioctl.h
> +++ b/drivers/media/video/cx18/cx18-ioctl.h
> @@ -1,4 +1,4 @@
> -/*
> + /*
> * cx18 ioctl system call
> *
> * Derived from ivtv-ioctl.h
> @@ -24,7 +24,6 @@
> u16 cx18_service2vbi(int type);
> void cx18_expand_service_set(struct v4l2_sliced_vbi_format *fmt, int is_pal);
> u16 cx18_get_service_set(struct v4l2_sliced_vbi_format *fmt);
> -int cx18_v4l2_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
> - unsigned long arg);
> +long cx18_v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
> int cx18_v4l2_ioctls(struct cx18 *cx, struct file *filp, unsigned cmd,
> void *arg);
> diff --git a/drivers/media/video/cx18/cx18-streams.c b/drivers/media/video/cx18/cx18-streams.c
> index afb141b..7348b82 100644
> --- a/drivers/media/video/cx18/cx18-streams.c
> +++ b/drivers/media/video/cx18/cx18-streams.c
> @@ -39,7 +39,7 @@ static struct file_operations cx18_v4l2_enc_fops = {
> .owner = THIS_MODULE,
> .read = cx18_v4l2_read,
> .open = cx18_v4l2_open,
> - .ioctl = cx18_v4l2_ioctl,
> + .unlocked_ioctl = cx18_v4l2_ioctl,
> .release = cx18_v4l2_close,
> .poll = cx18_v4l2_enc_poll,
> };
> diff --git a/drivers/media/video/ivtv/ivtv-ioctl.c b/drivers/media/video/ivtv/ivtv-ioctl.c
> index d508b5d..a481b2d 100644
> --- a/drivers/media/video/ivtv/ivtv-ioctl.c
> +++ b/drivers/media/video/ivtv/ivtv-ioctl.c
> @@ -1726,7 +1726,7 @@ static int ivtv_v4l2_do_ioctl(struct inode *inode, struct file *filp,
> return 0;
> }
>
> -static int ivtv_serialized_ioctl(struct ivtv *itv, struct inode *inode, struct file *filp,
> +static int ivtv_serialized_ioctl(struct ivtv *itv, struct file *filp,
> unsigned int cmd, unsigned long arg)
> {
> /* Filter dvb ioctls that cannot be handled by video_usercopy */
> @@ -1761,18 +1761,19 @@ static int ivtv_serialized_ioctl(struct ivtv *itv, struct inode *inode, struct f
> default:
> break;
> }
> - return video_usercopy(inode, filp, cmd, arg, ivtv_v4l2_do_ioctl);
> + return video_usercopy(filp, cmd, arg, ivtv_v4l2_do_ioctl);
> }
>
> -int ivtv_v4l2_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
> - unsigned long arg)
> +long ivtv_v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> struct ivtv_open_id *id = (struct ivtv_open_id *)filp->private_data;
> struct ivtv *itv = id->itv;
> int res;
>
> + lock_kernel();
> mutex_lock(&itv->serialize_lock);
> - res = ivtv_serialized_ioctl(itv, inode, filp, cmd, arg);
> + res = ivtv_serialized_ioctl(itv, filp, cmd, arg);
> mutex_unlock(&itv->serialize_lock);
> + unlock_kernel();
> return res;
> }
> diff --git a/drivers/media/video/ivtv/ivtv-ioctl.h b/drivers/media/video/ivtv/ivtv-ioctl.h
> index a03351b..6708ea0 100644
> --- a/drivers/media/video/ivtv/ivtv-ioctl.h
> +++ b/drivers/media/video/ivtv/ivtv-ioctl.h
> @@ -24,8 +24,7 @@
> u16 service2vbi(int type);
> void expand_service_set(struct v4l2_sliced_vbi_format *fmt, int is_pal);
> u16 get_service_set(struct v4l2_sliced_vbi_format *fmt);
> -int ivtv_v4l2_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
> - unsigned long arg);
> +long ivtv_v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
> int ivtv_v4l2_ioctls(struct ivtv *itv, struct file *filp, unsigned int cmd, void *arg);
> void ivtv_set_osd_alpha(struct ivtv *itv);
> int ivtv_set_speed(struct ivtv *itv, int speed);
> diff --git a/drivers/media/video/ivtv/ivtv-streams.c b/drivers/media/video/ivtv/ivtv-streams.c
> index 4ab8d36..3131f68 100644
> --- a/drivers/media/video/ivtv/ivtv-streams.c
> +++ b/drivers/media/video/ivtv/ivtv-streams.c
> @@ -48,7 +48,7 @@ static const struct file_operations ivtv_v4l2_enc_fops = {
> .read = ivtv_v4l2_read,
> .write = ivtv_v4l2_write,
> .open = ivtv_v4l2_open,
> - .ioctl = ivtv_v4l2_ioctl,
> + .unlocked_ioctl = ivtv_v4l2_ioctl,
> .release = ivtv_v4l2_close,
> .poll = ivtv_v4l2_enc_poll,
> };
> @@ -58,7 +58,7 @@ static const struct file_operations ivtv_v4l2_dec_fops = {
> .read = ivtv_v4l2_read,
> .write = ivtv_v4l2_write,
> .open = ivtv_v4l2_open,
> - .ioctl = ivtv_v4l2_ioctl,
> + .unlocked_ioctl = ivtv_v4l2_ioctl,
> .release = ivtv_v4l2_close,
> .poll = ivtv_v4l2_dec_poll,
> };
--
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