[PATCH] agp: remove read/write stubs

[PATCH] agp: remove read/write stubs

[Mathias Krause]

The VFS layer handles those in the very same way, if unset. No need for
additional stubs.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
---
 drivers/char/agp/frontend.c |   15 ---------------
 1 file changed, 15 deletions(-)

diff --git a/drivers/char/agp/frontend.c b/drivers/char/agp/frontend.c
index b29703324e..09f17eb734 100644
--- a/drivers/char/agp/frontend.c
+++ b/drivers/char/agp/frontend.c
@@ -710,19 +710,6 @@ static int agp_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
-
-static ssize_t agp_read(struct file *file, char __user *buf,
-			size_t count, loff_t * ppos)
-{
-	return -EINVAL;
-}
-
-static ssize_t agp_write(struct file *file, const char __user *buf,
-			 size_t count, loff_t * ppos)
-{
-	return -EINVAL;
-}
-
 static int agpioc_info_wrap(struct agp_file_private *priv, void __user *arg)
 {
 	struct agp_info userinfo;
@@ -1047,8 +1034,6 @@ static const struct file_operations agp_fops =
 {
 	.owner		= THIS_MODULE,
 	.llseek		= no_llseek,
-	.read		= agp_read,
-	.write		= agp_write,
 	.unlocked_ioctl	= agp_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= compat_agp_ioctl,
-- 
1.7.10.4

Re: [PATCH] agp: remove read/write stubs

[Mathias Krause]

On 15 June 2014 23:02, Mathias Krause <minipli@googlemail.com> wrote:
> The VFS layer handles those in the very same way, if unset. No need for
> additional stubs.
>
> Signed-off-by: Mathias Krause <minipli@googlemail.com>
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> ---
>  drivers/char/agp/frontend.c |   15 ---------------
>  1 file changed, 15 deletions(-)
>
> diff --git a/drivers/char/agp/frontend.c b/drivers/char/agp/frontend.c
> index b29703324e..09f17eb734 100644
> --- a/drivers/char/agp/frontend.c
> +++ b/drivers/char/agp/frontend.c
> @@ -710,19 +710,6 @@ static int agp_open(struct inode *inode, struct file *file)
>         return 0;
>  }
>
> -
> -static ssize_t agp_read(struct file *file, char __user *buf,
> -                       size_t count, loff_t * ppos)
> -{
> -       return -EINVAL;
> -}
> -
> -static ssize_t agp_write(struct file *file, const char __user *buf,
> -                        size_t count, loff_t * ppos)
> -{
> -       return -EINVAL;
> -}
> -
>  static int agpioc_info_wrap(struct agp_file_private *priv, void __user *arg)
>  {
>         struct agp_info userinfo;
> @@ -1047,8 +1034,6 @@ static const struct file_operations agp_fops =
>  {
>         .owner          = THIS_MODULE,
>         .llseek         = no_llseek,
> -       .read           = agp_read,
> -       .write          = agp_write,
>         .unlocked_ioctl = agp_ioctl,
>  #ifdef CONFIG_COMPAT
>         .compat_ioctl   = compat_agp_ioctl,
> --
> 1.7.10.4
>

Ping. Any objections, comments? David?

Re: [PATCH] agp: remove read/write stubs

[Dave Airlie]

On 2 July 2014 16:15, Mathias Krause <minipli@googlemail.com> wrote:
> On 15 June 2014 23:02, Mathias Krause <minipli@googlemail.com> wrote:
>> The VFS layer handles those in the very same way, if unset. No need for
>> additional stubs.
>>
>> Signed-off-by: Mathias Krause <minipli@googlemail.com>
>> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
>> ---
>>  drivers/char/agp/frontend.c |   15 ---------------
>>  1 file changed, 15 deletions(-)
>>
>> diff --git a/drivers/char/agp/frontend.c b/drivers/char/agp/frontend.c
>> index b29703324e..09f17eb734 100644
>> --- a/drivers/char/agp/frontend.c
>> +++ b/drivers/char/agp/frontend.c
>> @@ -710,19 +710,6 @@ static int agp_open(struct inode *inode, struct file *file)
>>         return 0;
>>  }
>>
>> -
>> -static ssize_t agp_read(struct file *file, char __user *buf,
>> -                       size_t count, loff_t * ppos)
>> -{
>> -       return -EINVAL;
>> -}
>> -
>> -static ssize_t agp_write(struct file *file, const char __user *buf,
>> -                        size_t count, loff_t * ppos)
>> -{
>> -       return -EINVAL;
>> -}
>> -
>>  static int agpioc_info_wrap(struct agp_file_private *priv, void __user *arg)
>>  {
>>         struct agp_info userinfo;
>> @@ -1047,8 +1034,6 @@ static const struct file_operations agp_fops =
>>  {
>>         .owner          = THIS_MODULE,
>>         .llseek         = no_llseek,
>> -       .read           = agp_read,
>> -       .write          = agp_write,
>>         .unlocked_ioctl = agp_ioctl,
>>  #ifdef CONFIG_COMPAT
>>         .compat_ioctl   = compat_agp_ioctl,
>> --
>> 1.7.10.4
>>
>
> Ping. Any objections, comments? David?

Are you sure VFS handles this the same way? can you point me where it
checks ->read and returns -EINVAL, I'm probably just missing it in my
quick look over fs/read_write.c

Dave.

Re: [PATCH] agp: remove read/write stubs

[Mathias Krause]

On 9 July 2014 00:48, Dave Airlie <airlied@gmail.com> wrote:
> On 2 July 2014 16:15, Mathias Krause <minipli@googlemail.com> wrote:
>> On 15 June 2014 23:02, Mathias Krause <minipli@googlemail.com> wrote:
>>> The VFS layer handles those in the very same way, if unset. No need for
>>> additional stubs.
>>>
>>> Signed-off-by: Mathias Krause <minipli@googlemail.com>
>>> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
>>> ---
>>>  drivers/char/agp/frontend.c |   15 ---------------
>>>  1 file changed, 15 deletions(-)
>>>
>>> diff --git a/drivers/char/agp/frontend.c b/drivers/char/agp/frontend.c
>>> index b29703324e..09f17eb734 100644
>>> --- a/drivers/char/agp/frontend.c
>>> +++ b/drivers/char/agp/frontend.c
>>> @@ -710,19 +710,6 @@ static int agp_open(struct inode *inode, struct file *file)
>>>         return 0;
>>>  }
>>>
>>> -
>>> -static ssize_t agp_read(struct file *file, char __user *buf,
>>> -                       size_t count, loff_t * ppos)
>>> -{
>>> -       return -EINVAL;
>>> -}
>>> -
>>> -static ssize_t agp_write(struct file *file, const char __user *buf,
>>> -                        size_t count, loff_t * ppos)
>>> -{
>>> -       return -EINVAL;
>>> -}
>>> -
>>>  static int agpioc_info_wrap(struct agp_file_private *priv, void __user *arg)
>>>  {
>>>         struct agp_info userinfo;
>>> @@ -1047,8 +1034,6 @@ static const struct file_operations agp_fops =
>>>  {
>>>         .owner          = THIS_MODULE,
>>>         .llseek         = no_llseek,
>>> -       .read           = agp_read,
>>> -       .write          = agp_write,
>>>         .unlocked_ioctl = agp_ioctl,
>>>  #ifdef CONFIG_COMPAT
>>>         .compat_ioctl   = compat_agp_ioctl,
>>> --
>>> 1.7.10.4
>>>
>>
>> Ping. Any objections, comments? David?
>
> Are you sure VFS handles this the same way? can you point me where it
> checks ->read and returns -EINVAL, I'm probably just missing it in my
> quick look over fs/read_write.c

The VFS code changed during the last merge window so the ->read and
->write tests are no longer directly visible. The presence of a ->read
/ ->write function is now remembered at open(2) time and stored in
->f_mode as a flag.

The corresponding commit for the VFS change is 7f7f25e82d "replace
checking for ->read/->aio_read presence with check in ->f_mode".
Despite its subject, it also handles ->write / ->aio_write. The flags
are set in fs/open:do_dentry_open():

    if ((f->f_mode & FMODE_READ) &&
         likely(f->f_op->read || f->f_op->aio_read || f->f_op->read_iter))
        f->f_mode |= FMODE_CAN_READ;
    if ((f->f_mode & FMODE_WRITE) &&
         likely(f->f_op->write || f->f_op->aio_write || f->f_op->write_iter))
        f->f_mode |= FMODE_CAN_WRITE;

With that change in mind, the redundancy of the agp_read() and
agp_write() functions can be seen for read(2) in vfs_read():

    if (!(file->f_mode & FMODE_CAN_READ))
        return -EINVAL;

..and for write(2) in vfs_write():

    if (!(file->f_mode & FMODE_CAN_WRITE))
        return -EINVAL;

The other entry points (readv / writev / compat wrappers) have been
changed accordingly, so those handle a missing ->read / ->write
callback in the same way: returning -EINVAL.

Regards,
Mathias

Re: [PATCH] agp: remove read/write stubs

[Mathias Krause]

On 9 July 2014 08:52, Mathias Krause <minipli@googlemail.com> wrote:
> On 9 July 2014 00:48, Dave Airlie <airlied@gmail.com> wrote:
>> On 2 July 2014 16:15, Mathias Krause <minipli@googlemail.com> wrote:
>>> On 15 June 2014 23:02, Mathias Krause <minipli@googlemail.com> wrote:
>>>> The VFS layer handles those in the very same way, if unset. No need for
>>>> additional stubs.
>>>>
>>>> Signed-off-by: Mathias Krause <minipli@googlemail.com>
>>>> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
>>>> ---
>>>>  drivers/char/agp/frontend.c |   15 ---------------
>>>>  1 file changed, 15 deletions(-)
>>>>
>>>> diff --git a/drivers/char/agp/frontend.c b/drivers/char/agp/frontend.c
>>>> index b29703324e..09f17eb734 100644
>>>> --- a/drivers/char/agp/frontend.c
>>>> +++ b/drivers/char/agp/frontend.c
>>>> @@ -710,19 +710,6 @@ static int agp_open(struct inode *inode, struct file *file)
>>>>         return 0;
>>>>  }
>>>>
>>>> -
>>>> -static ssize_t agp_read(struct file *file, char __user *buf,
>>>> -                       size_t count, loff_t * ppos)
>>>> -{
>>>> -       return -EINVAL;
>>>> -}
>>>> -
>>>> -static ssize_t agp_write(struct file *file, const char __user *buf,
>>>> -                        size_t count, loff_t * ppos)
>>>> -{
>>>> -       return -EINVAL;
>>>> -}
>>>> -
>>>>  static int agpioc_info_wrap(struct agp_file_private *priv, void __user *arg)
>>>>  {
>>>>         struct agp_info userinfo;
>>>> @@ -1047,8 +1034,6 @@ static const struct file_operations agp_fops =
>>>>  {
>>>>         .owner          = THIS_MODULE,
>>>>         .llseek         = no_llseek,
>>>> -       .read           = agp_read,
>>>> -       .write          = agp_write,
>>>>         .unlocked_ioctl = agp_ioctl,
>>>>  #ifdef CONFIG_COMPAT
>>>>         .compat_ioctl   = compat_agp_ioctl,
>>>> --
>>>> 1.7.10.4
>>>>
>>>
>>> Ping. Any objections, comments? David?
>>
>> Are you sure VFS handles this the same way? can you point me where it
>> checks ->read and returns -EINVAL, I'm probably just missing it in my
>> quick look over fs/read_write.c
>
> The VFS code changed during the last merge window so the ->read and
> ->write tests are no longer directly visible. The presence of a ->read
> / ->write function is now remembered at open(2) time and stored in
> ->f_mode as a flag.
>
> The corresponding commit for the VFS change is 7f7f25e82d "replace
> checking for ->read/->aio_read presence with check in ->f_mode".
> Despite its subject, it also handles ->write / ->aio_write. The flags
> are set in fs/open:do_dentry_open():
>
>     if ((f->f_mode & FMODE_READ) &&
>          likely(f->f_op->read || f->f_op->aio_read || f->f_op->read_iter))
>         f->f_mode |= FMODE_CAN_READ;
>     if ((f->f_mode & FMODE_WRITE) &&
>          likely(f->f_op->write || f->f_op->aio_write || f->f_op->write_iter))
>         f->f_mode |= FMODE_CAN_WRITE;
>
> With that change in mind, the redundancy of the agp_read() and
> agp_write() functions can be seen for read(2) in vfs_read():
>
>     if (!(file->f_mode & FMODE_CAN_READ))
>         return -EINVAL;
>
> ..and for write(2) in vfs_write():
>
>     if (!(file->f_mode & FMODE_CAN_WRITE))
>         return -EINVAL;
>
> The other entry points (readv / writev / compat wrappers) have been
> changed accordingly, so those handle a missing ->read / ->write
> callback in the same way: returning -EINVAL.
>
> Regards,
> Mathias

Ping. Any more comments, David?

Re: [PATCH] agp: remove read/write stubs

[Mathias Krause]

On 22 July 2014 21:50, Mathias Krause <minipli@googlemail.com> wrote:
> On 9 July 2014 08:52, Mathias Krause <minipli@googlemail.com> wrote:
>> On 9 July 2014 00:48, Dave Airlie <airlied@gmail.com> wrote:
>>> On 2 July 2014 16:15, Mathias Krause <minipli@googlemail.com> wrote:
>>>> On 15 June 2014 23:02, Mathias Krause <minipli@googlemail.com> wrote:
>>>>> The VFS layer handles those in the very same way, if unset. No need for
>>>>> additional stubs.
>>>>>
>>>>> Signed-off-by: Mathias Krause <minipli@googlemail.com>
>>>>> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
>>>>> ---
>>>>>  drivers/char/agp/frontend.c |   15 ---------------
>>>>>  1 file changed, 15 deletions(-)
>>>>>
>>>>> diff --git a/drivers/char/agp/frontend.c b/drivers/char/agp/frontend.c
>>>>> index b29703324e..09f17eb734 100644
>>>>> --- a/drivers/char/agp/frontend.c
>>>>> +++ b/drivers/char/agp/frontend.c
>>>>> @@ -710,19 +710,6 @@ static int agp_open(struct inode *inode, struct file *file)
>>>>>         return 0;
>>>>>  }
>>>>>
>>>>> -
>>>>> -static ssize_t agp_read(struct file *file, char __user *buf,
>>>>> -                       size_t count, loff_t * ppos)
>>>>> -{
>>>>> -       return -EINVAL;
>>>>> -}
>>>>> -
>>>>> -static ssize_t agp_write(struct file *file, const char __user *buf,
>>>>> -                        size_t count, loff_t * ppos)
>>>>> -{
>>>>> -       return -EINVAL;
>>>>> -}
>>>>> -
>>>>>  static int agpioc_info_wrap(struct agp_file_private *priv, void __user *arg)
>>>>>  {
>>>>>         struct agp_info userinfo;
>>>>> @@ -1047,8 +1034,6 @@ static const struct file_operations agp_fops =
>>>>>  {
>>>>>         .owner          = THIS_MODULE,
>>>>>         .llseek         = no_llseek,
>>>>> -       .read           = agp_read,
>>>>> -       .write          = agp_write,
>>>>>         .unlocked_ioctl = agp_ioctl,
>>>>>  #ifdef CONFIG_COMPAT
>>>>>         .compat_ioctl   = compat_agp_ioctl,
>>>>> --
>>>>> 1.7.10.4
>>>>>
>>>>
>>>> Ping. Any objections, comments? David?
>>>
>>> Are you sure VFS handles this the same way? can you point me where it
>>> checks ->read and returns -EINVAL, I'm probably just missing it in my
>>> quick look over fs/read_write.c
>>
>> The VFS code changed during the last merge window so the ->read and
>> ->write tests are no longer directly visible. The presence of a ->read
>> / ->write function is now remembered at open(2) time and stored in
>> ->f_mode as a flag.
>>
>> The corresponding commit for the VFS change is 7f7f25e82d "replace
>> checking for ->read/->aio_read presence with check in ->f_mode".
>> Despite its subject, it also handles ->write / ->aio_write. The flags
>> are set in fs/open:do_dentry_open():
>>
>>     if ((f->f_mode & FMODE_READ) &&
>>          likely(f->f_op->read || f->f_op->aio_read || f->f_op->read_iter))
>>         f->f_mode |= FMODE_CAN_READ;
>>     if ((f->f_mode & FMODE_WRITE) &&
>>          likely(f->f_op->write || f->f_op->aio_write || f->f_op->write_iter))
>>         f->f_mode |= FMODE_CAN_WRITE;
>>
>> With that change in mind, the redundancy of the agp_read() and
>> agp_write() functions can be seen for read(2) in vfs_read():
>>
>>     if (!(file->f_mode & FMODE_CAN_READ))
>>         return -EINVAL;
>>
>> ..and for write(2) in vfs_write():
>>
>>     if (!(file->f_mode & FMODE_CAN_WRITE))
>>         return -EINVAL;
>>
>> The other entry points (readv / writev / compat wrappers) have been
>> changed accordingly, so those handle a missing ->read / ->write
>> callback in the same way: returning -EINVAL.
>>
>> Regards,
>> Mathias
>
> Ping. Any more comments, David?

Ping, ping. David, did you had time to look at the patch again?

Regards,
Mathias

Re: [PATCH] agp: remove read/write stubs

[Dave Airlie]

> >
> > Ping. Any more comments, David?
> 
> Ping, ping. David, did you had time to look at the patch again?

Merged finally thanks for reminding me, agp is kinda a dead zone.

Dave.