Re: [PATCH] drm/loongson: Remove a useless check in cursor_plane_atomic_async_check()

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 10.07.23 um 13:34 schrieb suijingfeng:
> Hi,
>
> On 2023/7/10 18:39, Thomas Zimmermann wrote:
> > Am 10.07.23 um 12:24 schrieb Sui Jingfeng:
> > > Because smatch warnings:
> > >
> > > drivers/gpu/drm/loongson/lsdc_plane.c:199
> > > lsdc_cursor_plane_atomic_async_check()
> > > warn: variable dereferenced before check 'state' (see line 180)
> > >
> > > vim +/state +199 drivers/gpu/drm/loongson/lsdc_plane.c
> > >
> > > 174  static int
> > >       lsdc_cursor_plane_atomic_async_check(struct drm_plane *plane,
> > > 175                                       struct drm_atomic_state 
> > > *state)
> > > 176  {
> > > 177          struct drm_plane_state *new_state;
> > > 178          struct drm_crtc_state *crtc_state;
> > > 179
> > > 180          new_state = drm_atomic_get_new_plane_state(state, plane);
> > >                                                          ^^^^^
> > > state is dereferenced inside this function
> > >
> > > 181
> > > 182  if (!plane->state || !plane->state->fb) {
> > > 183          drm_dbg(plane->dev, "%s: state is NULL\n", plane->name);
> > > 184                  return -EINVAL;
> > > 185  }
> > > 186
> > > 187  if (new_state->crtc_w != new_state->crtc_h) {
> > > 188          drm_dbg(plane->dev, "unsupported cursor size: %ux%u\n",
> > > 189                  new_state->crtc_w, new_state->crtc_h);
> > > 190          return -EINVAL;
> > > 191  }
> > > 192
> > > 193  if (new_state->crtc_w != 64 && new_state->crtc_w != 32) {
> > > 194          drm_dbg(plane->dev, "unsupported cursor size: %ux%u\n",
> > > 195                  new_state->crtc_w, new_state->crtc_h);
> > > 196          return -EINVAL;
> > > 197  }
> > > 198
> > > 199  if (state) {
> > >           ^^^^^
> > > Checked too late!
> > >
> > > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > > Closes: https://lore.kernel.org/r/202307100423.rV7D05Uq-lkp@xxxxxxxxx/
> > > Signed-off-by: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
> >
> > Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> >
> > BTW, you're posting these patches for loongson, 
>
> I'm posting these patches for the drm/loongson driver in drm-misc and/or 
> drm-tip branch,
>
> what do you means for *loongson*,
>
> > but that driver is not yet in our tree?
>
> I already applied(push) drm/loongson driver to drm-misc-next branch,
>
> What do you means that by "not yet in our tree", linux kernel side?
>
> Am I missing something ?

No, it's my fault. I didn't update my branches correctly. :)

Best regards
Thomas

> > Best regards
> > Thomas
> >
> >
> > > ---
> > >   drivers/gpu/drm/loongson/lsdc_plane.c | 8 +-------
> > >   1 file changed, 1 insertion(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/loongson/lsdc_plane.c 
> > > b/drivers/gpu/drm/loongson/lsdc_plane.c
> > > index 2ab3db982aa3..0d5094633222 100644
> > > --- a/drivers/gpu/drm/loongson/lsdc_plane.c
> > > +++ b/drivers/gpu/drm/loongson/lsdc_plane.c
> > > @@ -196,13 +196,7 @@ static int 
> > > lsdc_cursor_plane_atomic_async_check(struct drm_plane *plane,
> > >           return -EINVAL;
> > >       }
> > >   -    if (state) {
> > > -        crtc_state = drm_atomic_get_existing_crtc_state(state, 
> > > new_state->crtc);
> > > -    } else {
> > > -        crtc_state = plane->crtc->state;
> > > -        drm_dbg(plane->dev, "%s: atomic state is NULL\n", plane->name);
> > > -    }
> > > -
> > > +    crtc_state = drm_atomic_get_existing_crtc_state(state, 
> > > new_state->crtc);
> > >       if (!crtc_state->active)
> > >           return -EINVAL;

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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