[Intel-gfx] [PATCH] drm/i915/guc: Don't take struct_mutex for object unreference

[Chris Wilson]

We no longer need to take the struct_mutex for freeing objects, and on
the finalisation paths here the mutex is not been used for serialisation
of the pointer access, so remove the BKL wart.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_guc_loader.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
index 1aa85236b788..77a5c27b9da0 100644
--- a/drivers/gpu/drm/i915/intel_guc_loader.c
+++ b/drivers/gpu/drm/i915/intel_guc_loader.c
@@ -699,12 +699,9 @@ static void guc_fw_fetch(struct drm_device *dev, struct intel_guc_fw *guc_fw)
 	DRM_DEBUG_DRIVER("GuC fw fetch status FAIL; err %d, fw %p, obj %p\n",
 		err, fw, guc_fw->guc_fw_obj);
 
-	mutex_lock(&dev->struct_mutex);
-	obj = guc_fw->guc_fw_obj;
+	obj = fetch_and_zero(&guc_fw->guc_fw_obj);
 	if (obj)
 		i915_gem_object_put(obj);
-	guc_fw->guc_fw_obj = NULL;
-	mutex_unlock(&dev->struct_mutex);
 
 	release_firmware(fw);		/* OK even if fw is NULL */
 	guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_FAIL;
@@ -781,16 +778,17 @@ void intel_guc_fini(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct intel_guc_fw *guc_fw = &dev_priv->guc.guc_fw;
+	struct drm_i915_gem_object *obj;
 
 	mutex_lock(&dev->struct_mutex);
 	guc_interrupts_release(dev_priv);
 	i915_guc_submission_disable(dev_priv);
 	i915_guc_submission_fini(dev_priv);
-
-	if (guc_fw->guc_fw_obj)
-		i915_gem_object_put(guc_fw->guc_fw_obj);
-	guc_fw->guc_fw_obj = NULL;
 	mutex_unlock(&dev->struct_mutex);
 
+	obj = fetch_and_zero(&guc_fw->guc_fw_obj);
+	if (obj)
+		i915_gem_object_put(obj);
+
 	guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_NONE;
 }
-- 
2.10.2