Hello Thomas Hellström,
The patch 2f6b90da9192: "drm/i915: Use vma resources for async
unbinding" from Jan 10, 2022, leads to the following Smatch static
checker warning:
drivers/gpu/drm/i915/i915_vma.c:515 i915_vma_bind()
error: we previously assumed 'work->vma_res' could be null (see line 487)
drivers/gpu/drm/i915/i915_vma.c
417 int i915_vma_bind(struct i915_vma *vma,
418 enum i915_cache_level cache_level,
419 u32 flags,
420 struct i915_vma_work *work,
421 struct i915_vma_resource *vma_res)
422 {
423 u32 bind_flags;
424 u32 vma_flags;
425 int ret;
426
427 lockdep_assert_held(&vma->vm->mutex);
428 GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
429 GEM_BUG_ON(vma->size > vma->node.size);
430
431 if (GEM_DEBUG_WARN_ON(range_overflows(vma->node.start,
432 vma->node.size,
433 vma->vm->total))) {
434 i915_vma_resource_free(vma_res);
435 return -ENODEV;
436 }
437
438 if (GEM_DEBUG_WARN_ON(!flags)) {
439 i915_vma_resource_free(vma_res);
440 return -EINVAL;
441 }
442
443 bind_flags = flags;
444 bind_flags &= I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND;
445
446 vma_flags = atomic_read(&vma->flags);
447 vma_flags &= I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND;
448
449 bind_flags &= ~vma_flags;
450 if (bind_flags == 0) {
451 i915_vma_resource_free(vma_res);
452 return 0;
453 }
454
455 GEM_BUG_ON(!atomic_read(&vma->pages_count));
456
457 /* Wait for or await async unbinds touching our range */
458 if (work && bind_flags & vma->vm->bind_async_flags)
459 ret = i915_vma_resource_bind_dep_await(vma->vm,
460 &work->base.chain,
461 vma->node.start,
462 vma->node.size,
463 true,
464 GFP_NOWAIT |
465 __GFP_RETRY_MAYFAIL |
466 __GFP_NOWARN);
467 else
468 ret = i915_vma_resource_bind_dep_sync(vma->vm, vma->node.start,
469 vma->node.size, true);
470 if (ret) {
471 i915_vma_resource_free(vma_res);
472 return ret;
473 }
474
475 if (vma->resource || !vma_res) {
^^^^^^^^
Let's assume vma->resource is NULL and vma_res is also NULL.
476 /* Rebinding with an additional I915_VMA_*_BIND */
477 GEM_WARN_ON(!vma_flags);
478 i915_vma_resource_free(vma_res);
479 } else {
480 i915_vma_resource_init_from_vma(vma_res, vma);
481 vma->resource = vma_res;
482 }
483 trace_i915_vma_bind(vma, bind_flags);
484 if (work && bind_flags & vma->vm->bind_async_flags) {
485 struct dma_fence *prev;
486
487 work->vma_res = i915_vma_resource_get(vma->resource);
If "vma->resource" is NULL here then it leads to a crash in i915_vma_resource_get().
488 work->cache_level = cache_level;
489 work->flags = bind_flags;
490
regards,
dan carpenter
