[Intel-gfx] [PATCH 166/190] drm/i915: Drop spinlocks around adding to the client request list

[Chris Wilson]

Adding to the tail of the client request list as the only other user is
in the throttle ioctl that iterates forwards over the list. It only
needs protection against deletion of a request as it reads it, it simply
won't see a new request added to the end of the list, or it would be too
early and rejected. We can further reduce the number of spinlocks
required when throttling by removing stale requests from the client_list
as we throttle.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c            | 10 ++++------
 drivers/gpu/drm/i915/i915_gem_execbuffer.c | 15 +++++++++------
 drivers/gpu/drm/i915/i915_gem_request.c    | 23 -----------------------
 drivers/gpu/drm/i915/i915_gem_request.h    |  2 --
 4 files changed, 13 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 5347469bbea1..e3d83e10918b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3436,12 +3436,10 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
 		if (time_after_eq(request->emitted_jiffies, recent_enough))
 			break;
 
-		/*
-		 * Note that the request might not have been submitted yet.
-		 * In which case emitted_jiffies will be zero.
-		 */
-		if (!request->emitted_jiffies)
-			continue;
+		if (target) {
+			list_del(&target->client_list);
+			target->file_priv = NULL;
+		}
 
 		target = request;
 	}
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index e60f559696d9..7014523cd890 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1322,6 +1322,14 @@ err:
 	return vma;
 }
 
+static void
+add_to_client(struct drm_i915_gem_request *req,
+	      struct drm_file *file)
+{
+	req->file_priv = file->driver_priv;
+	list_add_tail(&req->client_list, &req->file_priv->mm.request_list);
+}
+
 static int
 execbuf_submit(struct i915_execbuffer_params *params,
 	       struct drm_i915_gem_execbuffer2 *args,
@@ -1409,6 +1417,7 @@ execbuf_submit(struct i915_execbuffer_params *params,
 	trace_i915_gem_ring_dispatch(params->request, params->dispatch_flags);
 
 	i915_gem_execbuffer_move_to_active(vmas, params->request);
+	add_to_client(params->request, params->file);
 
 	return 0;
 }
@@ -1689,12 +1698,6 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 	 */
 	params->request->batch = params->batch_vma;
 
-	ret = i915_gem_request_add_to_client(params->request, file);
-	if (ret) {
-		i915_gem_request_cancel(params->request);
-		goto err_batch_unpin;
-	}
-
 	/*
 	 * Save assorted stuff away to pass through to *_submission().
 	 * NB: This data should be 'persistent' and not local as it will
diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index d922b78614bd..28977edfbb83 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -278,29 +278,6 @@ err:
 	return ERR_PTR(ret);
 }
 
-int i915_gem_request_add_to_client(struct drm_i915_gem_request *req,
-				   struct drm_file *file)
-{
-	struct drm_i915_file_private *file_priv;
-
-	WARN_ON(!req || !file || req->file_priv);
-
-	if (!req || !file)
-		return -EINVAL;
-
-	if (req->file_priv)
-		return -EINVAL;
-
-	file_priv = file->driver_priv;
-
-	spin_lock(&file_priv->mm.lock);
-	req->file_priv = file_priv;
-	list_add_tail(&req->client_list, &file_priv->mm.request_list);
-	spin_unlock(&file_priv->mm.lock);
-
-	return 0;
-}
-
 static inline void
 i915_gem_request_remove_from_client(struct drm_i915_gem_request *request)
 {
diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
index 67bc1f919af0..1e7c4fff5257 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.h
+++ b/drivers/gpu/drm/i915/i915_gem_request.h
@@ -94,8 +94,6 @@ struct drm_i915_gem_request *
 i915_gem_request_alloc(struct intel_engine_cs *ring,
 		       struct intel_context *ctx);
 void i915_gem_request_cancel(struct drm_i915_gem_request *req);
-int i915_gem_request_add_to_client(struct drm_i915_gem_request *req,
-				   struct drm_file *file);
 void i915_gem_request_retire_upto(struct drm_i915_gem_request *req);
 
 static inline uint32_t
-- 
2.7.0.rc3