[Intel-gfx] [PATCH v2, 2/4] drm/i915: simplify testing for the global default context

[Dave Gordon]

There are quite a number of places where the driver tests whether
a given context is or is not the global default context, usually by
checking whether an engine's default_pointer points to the context.
Now that we have a 'is_global_default' flag in the context itself,
all these tests these can be rewritten to use it. This makes the
logic more obvious, and usually saves at least one memory reference.
In addition, with these uses eliminated, a future patch will be able
to get rid of engine::default_context entirely.

Signed-off-by: Dave Gordon <david.s.gordon at intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 15 +++++---------
 drivers/gpu/drm/i915/i915_gem.c     |  6 ++----
 drivers/gpu/drm/i915/intel_lrc.c    | 40 +++++++++++++++++--------------------
 3 files changed, 25 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 0fc38bb..5e6e02c 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1942,11 +1942,8 @@ static int i915_context_status(struct seq_file *m, void *unused)
 
 		seq_puts(m, "HW context ");
 		describe_ctx(m, ctx);
-		for_each_ring(ring, dev_priv, i) {
-			if (ring->default_context == ctx)
-				seq_printf(m, "(default context %s) ",
-					   ring->name);
-		}
+		if (ctx->is_global_default)
+			seq_printf(m, "(default context) ");
 
 		if (i915.enable_execlists) {
 			seq_putc(m, '\n');
@@ -2037,13 +2034,11 @@ static int i915_dump_lrc(struct seq_file *m, void *unused)
 	if (ret)
 		return ret;
 
-	list_for_each_entry(ctx, &dev_priv->context_list, link) {
-		for_each_ring(ring, dev_priv, i) {
-			if (ring->default_context != ctx)
+	list_for_each_entry(ctx, &dev_priv->context_list, link)
+		if (!ctx->is_global_default)
+			for_each_ring(ring, dev_priv, i)
 				i915_dump_lrc_obj(m, ring,
 						  ctx->engine[i].state);
-		}
-	}
 
 	mutex_unlock(&dev->struct_mutex);
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6c60e04..d9a3304 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2677,10 +2677,8 @@ void i915_gem_request_free(struct kref *req_ref)
 		i915_gem_request_remove_from_client(req);
 
 	if (ctx) {
-		if (i915.enable_execlists) {
-			if (ctx != req->ring->default_context)
-				intel_lr_context_unpin(req);
-		}
+		if (i915.enable_execlists && !ctx->is_global_default)
+			intel_lr_context_unpin(req);
 
 		i915_gem_context_unreference(ctx);
 	}
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 3aa6147..cf76d28 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -571,7 +571,7 @@ static int execlists_context_queue(struct drm_i915_gem_request *request)
 	struct drm_i915_gem_request *cursor;
 	int num_elements = 0;
 
-	if (request->ctx != ring->default_context)
+	if (!request->ctx->is_global_default)
 		intel_lr_context_pin(request);
 
 	i915_gem_request_reference(request);
@@ -660,17 +660,14 @@ static int execlists_move_to_gpu(struct drm_i915_gem_request *req,
 
 int intel_logical_ring_alloc_request_extras(struct drm_i915_gem_request *request)
 {
-	int ret;
+	int ret = 0;
 
 	request->ringbuf = request->ctx->engine[request->ring->id].ringbuf;
 
-	if (request->ctx != request->ring->default_context) {
+	if (!request->ctx->is_global_default)
 		ret = intel_lr_context_pin(request);
-		if (ret)
-			return ret;
-	}
 
-	return 0;
+	return ret;
 }
 
 static int logical_ring_wait_for_space(struct drm_i915_gem_request *req,
@@ -967,7 +964,7 @@ void intel_execlists_retire_requests(struct intel_engine_cs *ring)
 		struct drm_i915_gem_object *ctx_obj =
 				ctx->engine[ring->id].state;
 
-		if (ctx_obj && (ctx != ring->default_context))
+		if (ctx_obj && !ctx->is_global_default)
 			intel_lr_context_unpin(req);
 		list_del(&req->execlist_link);
 		i915_gem_request_unreference(req);
@@ -2367,22 +2364,21 @@ void intel_lr_context_free(struct intel_context *ctx)
 {
 	int i;
 
-	for (i = 0; i < I915_NUM_RINGS; i++) {
+	for (i = I915_NUM_RINGS; --i >= 0; ) {
+		struct intel_ringbuffer *ringbuf = ctx->engine[i].ringbuf;
 		struct drm_i915_gem_object *ctx_obj = ctx->engine[i].state;
 
-		if (ctx_obj) {
-			struct intel_ringbuffer *ringbuf =
-					ctx->engine[i].ringbuf;
-			struct intel_engine_cs *ring = ringbuf->ring;
+		if (!ctx_obj)
+			continue;
 
-			if (ctx == ring->default_context) {
-				intel_unpin_ringbuffer_obj(ringbuf);
-				i915_gem_object_ggtt_unpin(ctx_obj);
-			}
-			WARN_ON(ctx->engine[ring->id].pin_count);
-			intel_ringbuffer_free(ringbuf);
-			drm_gem_object_unreference(&ctx_obj->base);
+		if (ctx->is_global_default) {
+			intel_unpin_ringbuffer_obj(ringbuf);
+			i915_gem_object_ggtt_unpin(ctx_obj);
 		}
+
+		WARN_ON(ctx->engine[i].pin_count);
+		intel_ringbuffer_free(ringbuf);
+		drm_gem_object_unreference(&ctx_obj->base);
 	}
 }
 
@@ -2443,7 +2439,7 @@ static void lrc_setup_hardware_status_page(struct intel_engine_cs *ring,
  */
 
 int intel_lr_context_deferred_alloc(struct intel_context *ctx,
-				     struct intel_engine_cs *ring)
+				    struct intel_engine_cs *ring)
 {
 	struct drm_device *dev = ring->dev;
 	struct drm_i915_gem_object *ctx_obj;
@@ -2480,7 +2476,7 @@ int intel_lr_context_deferred_alloc(struct intel_context *ctx,
 	ctx->engine[ring->id].ringbuf = ringbuf;
 	ctx->engine[ring->id].state = ctx_obj;
 
-	if (ctx != ring->default_context && ring->init_context) {
+	if (!ctx->is_global_default && ring->init_context) {
 		struct drm_i915_gem_request *req;
 
 		ret = i915_gem_request_alloc(ring,
-- 
1.9.1