Re: [PATCH] tools/iio: iio_event_monitor: Fix ioctl error check

[Jonathan Cameron]

+CC Alexandru Ardelean


On Mon, 3 May 2021 12:06:15 +0100
Jonathan Cameron <jic23@xxxxxxxxxx> wrote:

> On Wed, 28 Apr 2021 15:33:21 +0000
> "Sa, Nuno" <Nuno.Sa@xxxxxxxxxx> wrote:
> 
> > > From: Sa, Nuno <Nuno.Sa@xxxxxxxxxx>
> > > Sent: Wednesday, April 28, 2021 5:31 PM
> > > To: Paul Cercueil <paul@xxxxxxxxxxxxxxx>; Jonathan Cameron
> > > <jic23@xxxxxxxxxx>; Lars-Peter Clausen <lars@xxxxxxxxxx>; Peter
> > > Meerwald-Stadler <pmeerw@xxxxxxxxxx>
> > > Cc: linux-iio@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > > Subject: RE: [PATCH] tools/iio: iio_event_monitor: Fix ioctl error check
> > > 
> > >     
> > > > From: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> > > > Sent: Wednesday, April 28, 2021 5:08 PM
> > > > To: Jonathan Cameron <jic23@xxxxxxxxxx>; Lars-Peter Clausen
> > > > <lars@xxxxxxxxxx>; Peter Meerwald-Stadler
> > > > <pmeerw@xxxxxxxxxx>
> > > > Cc: linux-iio@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Paul
> > > > Cercueil <paul@xxxxxxxxxxxxxxx>
> > > > Subject: [PATCH] tools/iio: iio_event_monitor: Fix ioctl error check
> > > >
> > > >
> > > > The ioctrl() call will return errno=EINVAL if the device does not
> > > > support the events interface, and not ENODEV.
> > > >
> > > > Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>    
> > > 
> > > Reviewed-by: Nuno Sa <nuno.sa@xxxxxxxxxx>
> > >     
> > 
> > I guess this should have a Fixes: tag...  
> 
> So, I did a bit of detective work on this one.  Seems this change in error
> code was actually introduced as a side effect of Alex's recent rework of
> the IOCTLs.  Prior to that we returned -ENODEV for this case and now
> we do indeed return EINVAL.   
> 
> So we may need to figure out how to fix that, or decide that such is life
> and modify this code to give the right error message as done in this patch...
> 
> Linus / Alex, thoughts?  It's always been a bit messy because we also
> return -ENODEV in the path where the ioctl hits a driver that is going away
> so it hasn't uniquely identified a lack of support for a long time, even
> if that is by far the most likely reason for this return code.
> 
> Jonathan
> 
> 
> > 
> > - Nuno Sá  
>