drm/i915: Add i915_vma_unbind_unlocked, and take obj lock for i915_vma_unbind, v2.

We want to remove more members of i915_vma, which requires the locking to
be held more often.

Start requiring gem object lock for i915_vma_unbind, as it's one of the
callers that may unpin pages.

Some special care is needed when evicting, because the last reference to
the object may be held by the VMA, so after __i915_vma_unbind, vma may be
garbage, and we need to cache vma->obj before unlocking.

Changes since v1:
- Make trylock failing a WARN. (Matt)
- Remove double i915_vma_wait_for_bind() (Matt)
- Move atomic_set to right before mutex_unlock(), to make it more clear
  they belong together. (Matt)

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.william.auld@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220114132320.109030-5-maarten.lankhorst@linux.intel.com

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
index f61356b72b1c..ba29767348be 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
@@ -166,7 +166,9 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj,
 	kunmap(p);
 
 out:
+	i915_gem_object_lock(obj, NULL);
 	__i915_vma_put(vma);
+	i915_gem_object_unlock(obj);
 	return err;
 }
 
@@ -261,7 +263,9 @@ static int check_partial_mappings(struct drm_i915_gem_object *obj,
 		if (err)
 			return err;
 
+		i915_gem_object_lock(obj, NULL);
 		__i915_vma_put(vma);
+		i915_gem_object_unlock(obj);
 
 		if (igt_timeout(end_time,
 				"%s: timed out after tiling=%d stride=%d\n",
@@ -1352,7 +1356,9 @@ static int __igt_mmap_revoke(struct drm_i915_private *i915,
 	 * for other objects. Ergo we have to revoke the previous mmap PTE
 	 * access as it no longer points to the same object.
 	 */
+	i915_gem_object_lock(obj, NULL);
 	err = i915_gem_object_unbind(obj, I915_GEM_OBJECT_UNBIND_ACTIVE);
+	i915_gem_object_unlock(obj);
 	if (err) {
 		pr_err("Failed to unbind object!\n");
 		goto out_unmap;