[bug report] drm/msm: Support pgtable preallocation

[Dan Carpenter]

Hello Rob Clark,

Commit e601ea31d66b ("drm/msm: Support pgtable preallocation") from
Jun 29, 2025 (linux-next), leads to the following Smatch static
checker warning:

	drivers/gpu/drm/msm/msm_iommu.c:782 msm_iommu_gpu_new()
	error: we previously assumed 'adreno_smmu' could be null (see line 771)

drivers/gpu/drm/msm/msm_iommu.c
    760 struct msm_mmu *msm_iommu_gpu_new(struct device *dev, struct msm_gpu *gpu, unsigned long quirks)
    761 {
    762         struct adreno_smmu_priv *adreno_smmu = dev_get_drvdata(dev);
    763         struct msm_iommu *iommu;
    764         struct msm_mmu *mmu;
    765 
    766         mmu = msm_iommu_new(dev, quirks);
    767         if (IS_ERR_OR_NULL(mmu))
    768                 return mmu;
    769 
    770         iommu = to_msm_iommu(mmu);
    771         if (adreno_smmu && adreno_smmu->cookie) {
                    ^^^^^^^^^^^
The commit adds a NULL check.  Hopefully it can be removed.

    772                 const struct io_pgtable_cfg *cfg =
    773                         adreno_smmu->get_ttbr1_cfg(adreno_smmu->cookie);
    774                 size_t tblsz = get_tblsz(cfg);
    775 
    776                 iommu->pt_cache =
    777                         kmem_cache_create("msm-mmu-pt", tblsz, tblsz, 0, NULL);
    778         }
    779         iommu_set_fault_handler(iommu->domain, msm_gpu_fault_handler, iommu);
    780 
    781         /* Enable stall on iommu fault: */
--> 782         if (adreno_smmu->set_stall)
                    ^^^^^^^^^^^
because the old code dereferences "adreno_smmu" without checking.

    783                 adreno_smmu->set_stall(adreno_smmu->cookie, true);
    784 
    785         return mmu;
    786 }

regards,
dan carpenter