[drm-misc:drm-misc-next 2/3] drivers/gpu/drm/loongson/lsdc_plane.c:199 lsdc_cursor_plane_atomic_async_check() warn: variable dereferenced before check 'state' (see line 180)

[Dan Carpenter]

tree:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
head:   8d1077cf2e43b15fefd76ebec2b71541eb27ef2c
commit: f39db26c54281da6a785259498ca74b5e470476f [2/3] drm: Add kms driver for loongson display controller
config: i386-randconfig-m021-20230710 (https://download.01.org/0day-ci/archive/20230710/202307100423.rV7D05Uq-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce: (https://download.01.org/0day-ci/archive/20230710/202307100423.rV7D05Uq-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp at intel.com>
| Reported-by: Dan Carpenter <dan.carpenter at linaro.org>
| Closes: https://lore.kernel.org/r/202307100423.rV7D05Uq-lkp@intel.com/

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

f39db26c54281d Sui Jingfeng 2023-06-15  174  static int lsdc_cursor_plane_atomic_async_check(struct drm_plane *plane,
f39db26c54281d Sui Jingfeng 2023-06-15  175  						struct drm_atomic_state *state)
f39db26c54281d Sui Jingfeng 2023-06-15  176  {
f39db26c54281d Sui Jingfeng 2023-06-15  177  	struct drm_plane_state *new_state;
f39db26c54281d Sui Jingfeng 2023-06-15  178  	struct drm_crtc_state *crtc_state;
f39db26c54281d Sui Jingfeng 2023-06-15  179  
f39db26c54281d Sui Jingfeng 2023-06-15 @180  	new_state = drm_atomic_get_new_plane_state(state, plane);
                                                                                           ^^^^^
state is dereferenced inside this function

f39db26c54281d Sui Jingfeng 2023-06-15  181  
f39db26c54281d Sui Jingfeng 2023-06-15  182  	if (!plane->state || !plane->state->fb) {
f39db26c54281d Sui Jingfeng 2023-06-15  183  		drm_dbg(plane->dev, "%s: state is NULL\n", plane->name);
f39db26c54281d Sui Jingfeng 2023-06-15  184  		return -EINVAL;
f39db26c54281d Sui Jingfeng 2023-06-15  185  	}
f39db26c54281d Sui Jingfeng 2023-06-15  186  
f39db26c54281d Sui Jingfeng 2023-06-15  187  	if (new_state->crtc_w != new_state->crtc_h) {
f39db26c54281d Sui Jingfeng 2023-06-15  188  		drm_dbg(plane->dev, "unsupported cursor size: %ux%u\n",
f39db26c54281d Sui Jingfeng 2023-06-15  189  			new_state->crtc_w, new_state->crtc_h);
f39db26c54281d Sui Jingfeng 2023-06-15  190  		return -EINVAL;
f39db26c54281d Sui Jingfeng 2023-06-15  191  	}
f39db26c54281d Sui Jingfeng 2023-06-15  192  
f39db26c54281d Sui Jingfeng 2023-06-15  193  	if (new_state->crtc_w != 64 && new_state->crtc_w != 32) {
f39db26c54281d Sui Jingfeng 2023-06-15  194  		drm_dbg(plane->dev, "unsupported cursor size: %ux%u\n",
f39db26c54281d Sui Jingfeng 2023-06-15  195  			new_state->crtc_w, new_state->crtc_h);
f39db26c54281d Sui Jingfeng 2023-06-15  196  		return -EINVAL;
f39db26c54281d Sui Jingfeng 2023-06-15  197  	}
f39db26c54281d Sui Jingfeng 2023-06-15  198  
f39db26c54281d Sui Jingfeng 2023-06-15 @199  	if (state) {
                                                    ^^^^^
Checked too late

f39db26c54281d Sui Jingfeng 2023-06-15  200  		crtc_state = drm_atomic_get_existing_crtc_state(state, new_state->crtc);
f39db26c54281d Sui Jingfeng 2023-06-15  201  	} else {
f39db26c54281d Sui Jingfeng 2023-06-15  202  		crtc_state = plane->crtc->state;
f39db26c54281d Sui Jingfeng 2023-06-15  203  		drm_dbg(plane->dev, "%s: atomic state is NULL\n", plane->name);
f39db26c54281d Sui Jingfeng 2023-06-15  204  	}
f39db26c54281d Sui Jingfeng 2023-06-15  205  
f39db26c54281d Sui Jingfeng 2023-06-15  206  	if (!crtc_state->active)
f39db26c54281d Sui Jingfeng 2023-06-15  207  		return -EINVAL;
f39db26c54281d Sui Jingfeng 2023-06-15  208  
f39db26c54281d Sui Jingfeng 2023-06-15  209  	if (plane->state->crtc != new_state->crtc ||
f39db26c54281d Sui Jingfeng 2023-06-15  210  	    plane->state->src_w != new_state->src_w ||
f39db26c54281d Sui Jingfeng 2023-06-15  211  	    plane->state->src_h != new_state->src_h ||
f39db26c54281d Sui Jingfeng 2023-06-15  212  	    plane->state->crtc_w != new_state->crtc_w ||
f39db26c54281d Sui Jingfeng 2023-06-15  213  	    plane->state->crtc_h != new_state->crtc_h)
f39db26c54281d Sui Jingfeng 2023-06-15  214  		return -EINVAL;
f39db26c54281d Sui Jingfeng 2023-06-15  215  
f39db26c54281d Sui Jingfeng 2023-06-15  216  	if (new_state->visible != plane->state->visible)
f39db26c54281d Sui Jingfeng 2023-06-15  217  		return -EINVAL;
f39db26c54281d Sui Jingfeng 2023-06-15  218  
f39db26c54281d Sui Jingfeng 2023-06-15  219  	return drm_atomic_helper_check_plane_state(plane->state,
f39db26c54281d Sui Jingfeng 2023-06-15  220  						   crtc_state,
f39db26c54281d Sui Jingfeng 2023-06-15  221  						   DRM_PLANE_NO_SCALING,
f39db26c54281d Sui Jingfeng 2023-06-15  222  						   DRM_PLANE_NO_SCALING,
f39db26c54281d Sui Jingfeng 2023-06-15  223  						   true, true);
f39db26c54281d Sui Jingfeng 2023-06-15  224  }

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