[Intel-gfx] [PATCH v2 6/7] drm/i915: Add i915_gem_request_unreference__unlocked

[Chris Wilson]

We were missing a convenience stub to aquire the right mutex whilst
dropping the request, so add it.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.h | 13 +++++++++++++
 drivers/gpu/drm/i915/i915_gem.c |  8 ++------
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index afb552c1a4f8..eaf21605738f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2143,6 +2143,19 @@ i915_gem_request_unreference(struct drm_i915_gem_request *req)
 	kref_put(&req->ref, i915_gem_request_free);
 }
 
+static inline void
+i915_gem_request_unreference__unlocked(struct drm_i915_gem_request *req)
+{
+	if (req && !atomic_add_unless(&req->ref.refcount, -1, 1)) {
+		struct drm_device *dev = req->ring->dev;
+
+		mutex_lock(&dev->struct_mutex);
+		if (likely(atomic_dec_and_test(&req->ref.refcount)))
+			i915_gem_request_free(&req->ref);
+		mutex_unlock(&dev->struct_mutex);
+	}
+}
+
 static inline void i915_gem_request_assign(struct drm_i915_gem_request **pdst,
 					   struct drm_i915_gem_request *src)
 {
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e2876bf83da7..3df65fc2aa74 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2957,9 +2957,7 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 	ret = __i915_wait_request(req, reset_counter, true,
 				  args->timeout_ns > 0 ? &args->timeout_ns : NULL,
 				  file->driver_priv);
-	mutex_lock(&dev->struct_mutex);
-	i915_gem_request_unreference(req);
-	mutex_unlock(&dev->struct_mutex);
+	i915_gem_request_unreference__unlocked(req);
 	return ret;
 
 out:
@@ -4146,9 +4144,7 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
 	if (ret == 0)
 		queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, 0);
 
-	mutex_lock(&dev->struct_mutex);
-	i915_gem_request_unreference(target);
-	mutex_unlock(&dev->struct_mutex);
+	i915_gem_request_unreference__unlocked(target);
 
 	return ret;
 }
-- 
2.1.4