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

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Message-ID: <20180306101331.GD22212@phenom.ffwll.local>
Date:   Tue, 6 Mar 2018 11:13:31 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Liviu Dudau <Liviu.Dudau@....com>
Cc:     Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>,
        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 04:34:30PM +0000, Liviu Dudau wrote:
> On Wed, Feb 28, 2018 at 05:57:15PM +0200, Ville Syrjälä wrote:
> > On Wed, Feb 28, 2018 at 03:44:44PM +0000, Liviu Dudau wrote:
> > > 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 :)
> > 
> > Plenty of non-bools in driver specific counterparts I believe.
> 
> So, is that a NACK? 

Yeah I think this is overoptimizing for not repeating code.
-Daniel

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

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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