Hello Thomas Hellstrom,
The patch 667a50db0477: "drm/ttm: Refuse to fault (prime-) imported
pages" from Jan 3, 2014, leads to the following static checker
warning:
drivers/gpu/drm/ttm/ttm_bo_vm.c:205 ttm_bo_vm_fault()
error: we previously assumed 'ttm' could be null (see line 200)
drivers/gpu/drm/ttm/ttm_bo_vm.c
133 /*
134 * Refuse to fault imported pages. This should be handled
135 * (if at all) by redirecting mmap to the exporter.
136 */
137 if (bo->ttm && (bo->ttm->page_flags & TTM_PAGE_FLAG_SG)) {
^^^^^^^
New check for NULL. Is this really needed?
138 retval = VM_FAULT_SIGBUS;
139 goto out_unlock;
140 }
[ snip ]
188 /*
189 * Make a local vma copy to modify the page_prot member
190 * and vm_flags if necessary. The vma parameter is protected
191 * by mmap_sem in write mode.
192 */
193 cvma = *vma;
194 cvma.vm_page_prot = vm_get_page_prot(cvma.vm_flags);
195
196 if (bo->mem.bus.is_iomem) {
197 cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
198 cvma.vm_page_prot);
199 } else {
200 ttm = bo->ttm;
^^^^^^^^^^^^^
201 cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
202 cvma.vm_page_prot);
203
204 /* Allocate all page at once, most common usage */
205 if (ttm->bdev->driver->ttm_tt_populate(ttm)) {
^^^^^^^^^
Old unchecked dereference.
206 retval = VM_FAULT_OOM;
207 goto out_io_unlock;
208 }
209 }
210
regards,
dan carpenter
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