Re: [PATCH 5/9] accel/neutron: Add GEM buffer object support

Re: [PATCH 5/9] accel/neutron: Add GEM buffer object support

[kernel test robot]

Hi Ioana,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f]

url:    https://github.com/intel-lab-lkp/linux/commits/Ioana-Ciocoi-Radulescu/drm-gem-dma-Add-flag-for-bidirectional-mapping-of-non-coherent-GEM-DMA-buffers/20260226-221222
base:   6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
patch link:    https://lore.kernel.org/r/20260226-neutron-v1-5-46eccb3bb50a%40nxp.com
patch subject: [PATCH 5/9] accel/neutron: Add GEM buffer object support
config: arm64-allmodconfig (https://download.01.org/0day-ci/archive/20260227/202602270531.MP8x6wo3-lkp@intel.com/config)
compiler: clang version 19.1.7 (https://github.com/llvm/llvm-project cd708029e0b2869e80abe31ddb175f7c35361f90)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260227/202602270531.MP8x6wo3-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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202602270531.MP8x6wo3-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/accel/neutron/neutron_gem.c:52:6: warning: variable 'gem_obj' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
      52 |         if (drm_WARN_ON(drm, !IS_ALIGNED(dma_obj->dma_addr, NEUTRON_BO_ALIGN))) {
         |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/drm/drm_print.h:789:2: note: expanded from macro 'drm_WARN_ON'
     789 |         drm_WARN((drm), (x), "%s",                                      \
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     790 |                  "drm_WARN_ON(" __stringify(x) ")")
         |                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/drm/drm_print.h:779:2: note: expanded from macro 'drm_WARN'
     779 |         WARN(condition, "%s %s: [drm] " format,                         \
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     780 |                         dev_driver_string(__drm_to_dev(drm)),           \
         |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     781 |                         dev_name(__drm_to_dev(drm)), ## arg)
         |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/asm-generic/bug.h:163:36: note: expanded from macro 'WARN'
     163 | #define WARN(condition, format...) ({                                   \
         |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     164 |         int __ret_warn_on = !!(condition);                              \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     165 |         if (unlikely(__ret_warn_on))                                    \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     166 |                 __WARN_printf(TAINT_WARN, format);                      \
         |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     167 |         unlikely(__ret_warn_on);                                        \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     168 | })
         | ~~
   drivers/accel/neutron/neutron_gem.c:67:21: note: uninitialized use occurs here
      67 |         drm_gem_object_put(gem_obj);
         |                            ^~~~~~~
   drivers/accel/neutron/neutron_gem.c:52:2: note: remove the 'if' if its condition is always false
      52 |         if (drm_WARN_ON(drm, !IS_ALIGNED(dma_obj->dma_addr, NEUTRON_BO_ALIGN))) {
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      53 |                 ret = -EFAULT;
         |                 ~~~~~~~~~~~~~~
      54 |                 goto out_put;
         |                 ~~~~~~~~~~~~~
      55 |         }
         |         ~
   drivers/accel/neutron/neutron_gem.c:38:32: note: initialize the variable 'gem_obj' to silence this warning
      38 |         struct drm_gem_object *gem_obj;
         |                                       ^
         |                                        = NULL
   1 warning generated.


vim +52 drivers/accel/neutron/neutron_gem.c

    33	
    34	int neutron_ioctl_create_bo(struct drm_device *drm, void *data, struct drm_file *filp)
    35	{
    36		struct drm_neutron_create_bo *args = data;
    37		struct drm_gem_dma_object *dma_obj;
    38		struct drm_gem_object *gem_obj;
    39		size_t size;
    40		int ret;
    41	
    42		if (!args->size || args->pad)
    43			return -EINVAL;
    44	
    45		size = ALIGN(args->size, NEUTRON_BO_ALIGN);
    46	
    47		dma_obj = drm_gem_dma_create(drm, size);
    48		if (IS_ERR(dma_obj))
    49			return PTR_ERR(dma_obj);
    50	
    51		/* We expect correctly aligned buffers, but double-check */
  > 52		if (drm_WARN_ON(drm, !IS_ALIGNED(dma_obj->dma_addr, NEUTRON_BO_ALIGN))) {
    53			ret = -EFAULT;
    54			goto out_put;
    55		}
    56	
    57		gem_obj = &dma_obj->base;
    58		ret = drm_gem_handle_create(filp, gem_obj, &args->handle);
    59		if (ret)
    60			goto out_put;
    61	
    62		args->map_offset = drm_vma_node_offset_addr(&gem_obj->vma_node);
    63		args->size = gem_obj->size;
    64	
    65	out_put:
    66		/* No need to keep a reference of the GEM object. Freeing is handled by user */
    67		drm_gem_object_put(gem_obj);
    68	
    69		return ret;
    70	}
    71	

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