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

[Vlad Zolotarov]

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@xxxxxxxxxxxxxxxxxxxx>
> > > > ---
> > > >   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

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