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

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

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?

>
> greg k-h