[Intel-gfx] [PATCH 04/23] drm/i915/gem: Only revoke mmap handlers if active

[Chris Wilson]

Avoid waking up the device and taking stale locks if we know that the
object is not currently mmapped. This is particularly useful as not many
object are actually mmapped and so we can destroy them without waking
the device up, and gives us a little more freedom of workqueue ordering
during shutdown.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gem/i915_gem_mman.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index fe27c5b344e3..522ca4f51b53 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -516,8 +516,11 @@ void i915_gem_object_release_mmap_offset(struct drm_i915_gem_object *obj)
  */
 void i915_gem_object_release_mmap(struct drm_i915_gem_object *obj)
 {
-	i915_gem_object_release_mmap_gtt(obj);
-	i915_gem_object_release_mmap_offset(obj);
+	if (obj->userfault_count)
+		i915_gem_object_release_mmap_gtt(obj);
+
+	if (!RB_EMPTY_ROOT(&obj->mmo.offsets))
+		i915_gem_object_release_mmap_offset(obj);
 }
 
 static struct i915_mmap_offset *
-- 
2.20.1