linux-kernel - Re: [PATCH] drm/drm_ioctl.c: Test client capability value early when setting.

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Date:   Wed, 28 Feb 2018 15:44:44 +0000
From:   Liviu Dudau <Liviu.Dudau@....com>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:     DRI-devel <dri-devel@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/drm_ioctl.c: Test client capability value early when
 setting.

On Wed, Feb 28, 2018 at 05:40:41PM +0200, Ville Syrjälä wrote:
> On Wed, Feb 28, 2018 at 03:27:41PM +0000, Liviu Dudau wrote:
> > The drm_setclientcap() function implementing the DRM_IOCTL_SET_CLIENT_CAP
> > ioctl expects that any capability set by the client will have a value of 1.
> > Make the check early so that we don't have to test the value for each
> > capability.
> 
> What if we want a a non-boolean capability at some point?

Well, I'm adding another boolean capability soon, so you will be going
against the trend :)

I guess you will have 2 options: revert the patch or add a condition to
the test.

I don't have strong feelings, just felt like too much copying when
adding another capability so I thought to do some "cleanup".

Best regards,
Liviu

> 
> > 
> > Signed-off-by: Liviu Dudau <liviu.dudau@....com>
> > ---
> >  drivers/gpu/drm/drm_ioctl.c | 9 +++------
> >  1 file changed, 3 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> > index af782911c505..02ffa0e8d77b 100644
> > --- a/drivers/gpu/drm/drm_ioctl.c
> > +++ b/drivers/gpu/drm/drm_ioctl.c
> > @@ -306,22 +306,19 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
> >  {
> >  	struct drm_set_client_cap *req = data;
> >  
> > +	if (req->value > 1)
> > +		return -EINVAL;
> > +
> >  	switch (req->capability) {
> >  	case DRM_CLIENT_CAP_STEREO_3D:
> > -		if (req->value > 1)
> > -			return -EINVAL;
> >  		file_priv->stereo_allowed = req->value;
> >  		break;
> >  	case DRM_CLIENT_CAP_UNIVERSAL_PLANES:
> > -		if (req->value > 1)
> > -			return -EINVAL;
> >  		file_priv->universal_planes = req->value;
> >  		break;
> >  	case DRM_CLIENT_CAP_ATOMIC:
> >  		if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
> >  			return -EINVAL;
> > -		if (req->value > 1)
> > -			return -EINVAL;
> >  		file_priv->atomic = req->value;
> >  		file_priv->universal_planes = req->value;
> >  		break;
> > -- 
> > 2.16.2
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@...ts.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Ville Syrjälä
> Intel OTC

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯

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