Re: [PATCH v5 1/4] uio: add ioctl support

[Vlad Zolotarov <vladz@cloudius-systems.com>]

On 10/07/15 20:21, Greg KH wrote:
> On Wed, Oct 07, 2015 at 11:55:01AM +0300, Vlad Zolotarov wrote:
>>
>> On 10/07/15 11:46, Greg KH wrote:
>>> On Tue, Oct 06, 2015 at 08:17:36PM +0300, Vlad Zolotarov wrote:
>>>> Add the ability for underlying device drivers to register the ioctl
>>>> commands. This is useful when some interaction with the user space
>>>> beyond sysfs capabilities is required, e.g. query the interrupt mode
>>>> or bind eventfd to interrupt notifications (similarly to vfio ioctl
>>>> VFIO_DEVICE_SET_IRQS).
>>>>
>>>> Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
>>>> ---
>>>>   drivers/uio/uio.c          | 15 +++++++++++++++
>>>>   include/linux/uio_driver.h |  3 +++
>>>>   2 files changed, 18 insertions(+)
>>>>
>>>> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
>>>> index 8196581..714b0e5 100644
>>>> --- a/drivers/uio/uio.c
>>>> +++ b/drivers/uio/uio.c
>>>> @@ -704,6 +704,20 @@ static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
>>>>   	}
>>>>   }
>>>> +static long uio_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
>>>> +{
>>>> +	struct uio_listener *listener = filep->private_data;
>>>> +	struct uio_device *idev = listener->dev;
>>>> +
>>>> +	if (!idev->info)
>>>> +		return -EIO;
>>>> +
>>>> +	if (!idev->info->ioctl)
>>>> +		return -ENOTTY;
>>>> +
>>>> +	return idev->info->ioctl(idev->info, cmd, arg);
>>>> +}
>>> As Stephen said, I will not take this, sorry.  It opens up the ability
>>> to add "new system calls" to a huge range of crappy drivers, it's
>>> something that vendors have been trying to push for years and is
>>> something that I will not allow.
>> Ok. Another alternative could be to add new sysfs attributes for the MSI-X
>> functionality similarly to what is done with "maps".
>> Would it be acceptable?
> If you get everyone else here to agree that this is the interface you
> all are going to be using, sure.  All I care is that you not add ioctl
> to the UIO interface.

Ok then. Thanks.

>
> greg k-h