On 1/28/22 09:57, Maarten Lankhorst wrote:
i915_gem_vm_close may take the lock, and we currently have no better way
of handling this. At least for now, allow a path in which holding vm->mutex
is sufficient. This is the case, because the object destroy path will
forcefully take vm->mutex now.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Reviewed-by: Thomas Hellstrom <thomas.hellstrom@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_vma.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index b959e904c4d3..14a301c4069f 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -40,6 +40,17 @@
#include "i915_vma.h"
#include "i915_vma_resource.h"
+static inline void assert_vma_held_evict(const struct i915_vma *vma)
+{
+ /*
+ * We may be forced to unbind when the vm is dead, to clean it up.
+ * This is the only exception to the requirement of the object lock
+ * being held.
+ */
+ if (atomic_read(&vma->vm->open))
+ assert_object_held_shared(vma->obj);
+}
+
static struct kmem_cache *slab_vmas;
static struct i915_vma *i915_vma_alloc(void)
@@ -1779,7 +1790,7 @@ struct dma_fence *__i915_vma_evict(struct i915_vma *vma, bool async)
struct dma_fence *unbind_fence;
GEM_BUG_ON(i915_vma_is_pinned(vma));
- assert_object_held_shared(vma->obj);
+ assert_vma_held_evict(vma);
if (i915_vma_is_map_and_fenceable(vma)) {
/* Force a pagefault for domain tracking on next user access */
@@ -1846,7 +1857,7 @@ int __i915_vma_unbind(struct i915_vma *vma)
int ret;
lockdep_assert_held(&vma->vm->mutex);
- assert_object_held_shared(vma->obj);
+ assert_vma_held_evict(vma);
if (!drm_mm_node_allocated(&vma->node))
return 0;
