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

[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 ?


> 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;