[leon-rdma:dma-static-calls-v1 2/2] kernel/dma/mapping.c:746:12: warning: variable 'sgt' is used uninitialized whenever 'if' condition is false

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git dma-static-calls-v1
head:   3acafa88e3e0ffeb1d7d2ae1e78d5c669edb55b6
commit: 3acafa88e3e0ffeb1d7d2ae1e78d5c669edb55b6 [2/2] dma: Add IOMMU static calls with clear default ops
config: x86_64-allnoconfig (https://download.01.org/0day-ci/archive/20240715/202407150312.GTJusNmx-lkp@intel.com/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240715/202407150312.GTJusNmx-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/202407150312.GTJusNmx-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/dma/mapping.c:746:12: warning: variable 'sgt' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     746 |                 else if (ops->alloc_noncontiguous)
         |                          ^~~~~~~~~~~~~~~~~~~~~~~~
   kernel/dma/mapping.c:753:6: note: uninitialized use occurs here
     753 |         if (sgt) {
         |             ^~~
   kernel/dma/mapping.c:746:8: note: remove the 'if' if its condition is always true
     746 |                 else if (ops->alloc_noncontiguous)
         |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     747 |                         sgt = ops->alloc_noncontiguous(dev, size, dir, gfp,
   kernel/dma/mapping.c:735:22: note: initialize the variable 'sgt' to silence this warning
     735 |         struct sg_table *sgt;
         |                             ^
         |                              = NULL
   1 warning generated.


vim +746 kernel/dma/mapping.c

   730	
   731	struct sg_table *dma_alloc_noncontiguous(struct device *dev, size_t size,
   732			enum dma_data_direction dir, gfp_t gfp, unsigned long attrs)
   733	{
   734		const struct dma_map_ops *ops = get_dma_ops(dev);
   735		struct sg_table *sgt;
   736	
   737		if (WARN_ON_ONCE(attrs & ~DMA_ATTR_ALLOC_SINGLE_PAGES))
   738			return NULL;
   739		if (WARN_ON_ONCE(gfp & __GFP_COMP))
   740			return NULL;
   741	
   742		if (ops) {
   743			if (dma_is_default_iommu(ops))
   744				sgt = iommu_dma_alloc_noncontiguous(dev, size, dir, gfp,
   745								    attrs);
 > 746			else if (ops->alloc_noncontiguous)
   747				sgt = ops->alloc_noncontiguous(dev, size, dir, gfp,
   748							       attrs);
   749		}
   750		else
   751			sgt = alloc_single_sgt(dev, size, dir, gfp);
   752	
   753		if (sgt) {
   754			sgt->nents = 1;
   755			debug_dma_map_sg(dev, sgt->sgl, sgt->orig_nents, 1, dir, attrs);
   756		}
   757		return sgt;
   758	}
   759	EXPORT_SYMBOL_GPL(dma_alloc_noncontiguous);
   760	

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