Re: [PATCH 5/7] drm/client: Remove drm_client_framebuffer_delete()

[Dan Carpenter <dan.carpenter@linaro.org>]

Hi Thomas,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Thomas-Zimmermann/drm-client-Remove-pitch-from-struct-drm_client_buffer/20251020-231709
base:   git://anongit.freedesktop.org/drm/drm drm-next
patch link:    https://lore.kernel.org/r/20251020151402.53013-6-tzimmermann%40suse.de
patch subject: [PATCH 5/7] drm/client: Remove drm_client_framebuffer_delete()
config: openrisc-randconfig-r072-20251021 (https://download.01.org/0day-ci/archive/20251022/202510220056.J4uIVWxn-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 12.5.0

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@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202510220056.J4uIVWxn-lkp@intel.com/

smatch warnings:
drivers/gpu/drm/drm_client.c:185 drm_client_buffer_delete() warn: variable dereferenced before check 'buffer' (see line 182)

vim +/buffer +185 drivers/gpu/drm/drm_client.c

449148a7300b8b Thomas Zimmermann 2025-10-20  180  void drm_client_buffer_delete(struct drm_client_buffer *buffer)
c76f0f7cb546b6 Noralf Trønnes    2018-07-03  181  {
95d6cf3a3cf1a1 Thomas Zimmermann 2025-10-20 @182  	struct drm_gem_object *gem = drm_gem_fb_get_obj(buffer->fb, 0);
                                                                                                        ^^^^^^^^^^
buffer is dereferenced here

82e2a75e5a640c Thomas Zimmermann 2025-10-20  183  	int ret;
82e2a75e5a640c Thomas Zimmermann 2025-10-20  184  
449148a7300b8b Thomas Zimmermann 2025-10-20 @185  	if (!buffer)
                                                            ^^^^^^^
checked too late

449148a7300b8b Thomas Zimmermann 2025-10-20  186  		return;
449148a7300b8b Thomas Zimmermann 2025-10-20  187  
95d6cf3a3cf1a1 Thomas Zimmermann 2025-10-20  188  	drm_gem_vunmap(gem, &buffer->map);
95d6cf3a3cf1a1 Thomas Zimmermann 2025-10-20  189  
82e2a75e5a640c Thomas Zimmermann 2025-10-20  190  	ret = drm_mode_rmfb(buffer->client->dev, buffer->fb->base.id, buffer->client->file);
82e2a75e5a640c Thomas Zimmermann 2025-10-20  191  	if (ret)
82e2a75e5a640c Thomas Zimmermann 2025-10-20  192  		drm_err(buffer->client->dev,
82e2a75e5a640c Thomas Zimmermann 2025-10-20  193  			"Error removing FB:%u (%d)\n", buffer->fb->base.id, ret);
82e2a75e5a640c Thomas Zimmermann 2025-10-20  194  
be6ee102341bc4 Emil Velikov      2020-05-15  195  	drm_gem_object_put(buffer->gem);
c76f0f7cb546b6 Noralf Trønnes    2018-07-03  196  
c76f0f7cb546b6 Noralf Trønnes    2018-07-03  197  	kfree(buffer);
c76f0f7cb546b6 Noralf Trønnes    2018-07-03  198  }

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