[Intel-gfx] [PATCH 1/4] drm/i915: The shrinker already acquires struct_mutex, so call it unlocked

[Chris Wilson]

The shrinker is prepared to be called unlock (and with struct_mutex held
for DIRECT_RECLAIM) so we can skip acquiring the struct_mutex prior to
calling the shrinking during freeze. This improves our ability to shrink
as we can be more aggressive when we know the caller isn't holding
struct_mutex.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 52b403b4f8c2..13cad69df20e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4886,9 +4886,10 @@ void i915_gem_load_cleanup(struct drm_i915_private *dev_priv)
 
 int i915_gem_freeze(struct drm_i915_private *dev_priv)
 {
-	mutex_lock(&dev_priv->drm.struct_mutex);
+	/* Discard all purgeable objects, let userspace recover those as
+	 * required after resuming.
+	 */
 	i915_gem_shrink_all(dev_priv);
-	mutex_unlock(&dev_priv->drm.struct_mutex);
 
 	return 0;
 }
@@ -4913,12 +4914,12 @@ int i915_gem_freeze_late(struct drm_i915_private *dev_priv)
 	 * we update that state just before writing out the image.
 	 *
 	 * To try and reduce the hibernation image, we manually shrink
-	 * the objects as well.
+	 * the objects as well, see i915_gem_freeze()
 	 */
 
-	mutex_lock(&dev_priv->drm.struct_mutex);
 	i915_gem_shrink(dev_priv, -1UL, I915_SHRINK_UNBOUND);
 
+	mutex_lock(&dev_priv->drm.struct_mutex);
 	for (p = phases; *p; p++) {
 		list_for_each_entry(obj, *p, global_link) {
 			obj->base.read_domains = I915_GEM_DOMAIN_CPU;
-- 
2.11.0