drm/i915: Pull the context->pin_count dec into the common intel_context_unpin

As all backends implement the same pin_count mechanism and do a
dec-and-test as their first step, pull that into the common
intel_context_unpin(). This also pulls into the caller, eliminating the
indirect call in the usual steady state case. The intel_context_pin()
side is a little more complicated as it combines the lookup/alloc as
well as pinning the state, and so is left for a later date.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180517212633.24934-4-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_context.h

@@ -285,6 +285,10 @@ static inline void __intel_context_pin(struct intel_context *ce)
 
 static inline void intel_context_unpin(struct intel_context *ce)
 {
+	GEM_BUG_ON(!ce->pin_count);
+	if (--ce->pin_count)
+		return;
+
 	GEM_BUG_ON(!ce->ops);
 	ce->ops->unpin(ce);
 }

drivers/gpu/drm/i915/intel_lrc.c

@@ -1343,7 +1343,7 @@ static void execlists_context_destroy(struct intel_context *ce)
 	__i915_gem_object_release_unless_active(ce->state->obj);
 }
 
-static void __execlists_context_unpin(struct intel_context *ce)
+static void execlists_context_unpin(struct intel_context *ce)
 {
 	intel_ring_unpin(ce->ring);
 
@@ -1354,17 +1354,6 @@ static void __execlists_context_unpin(struct intel_context *ce)
 	i915_gem_context_put(ce->gem_context);
 }
 
-static void execlists_context_unpin(struct intel_context *ce)
-{
-	lockdep_assert_held(&ce->gem_context->i915->drm.struct_mutex);
-	GEM_BUG_ON(ce->pin_count == 0);
-
-	if (--ce->pin_count)
-		return;
-
-	__execlists_context_unpin(ce);
-}
-
 static int __context_pin(struct i915_gem_context *ctx, struct i915_vma *vma)
 {
 	unsigned int flags;

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1195,12 +1195,6 @@ static void intel_ring_context_destroy(struct intel_context *ce)
 
 static void intel_ring_context_unpin(struct intel_context *ce)
 {
-	lockdep_assert_held(&ce->gem_context->i915->drm.struct_mutex);
-	GEM_BUG_ON(ce->pin_count == 0);
-
-	if (--ce->pin_count)
-		return;
-
 	if (ce->state) {
 		ce->state->obj->pin_global--;
 		i915_vma_unpin(ce->state);

drivers/gpu/drm/i915/selftests/mock_engine.c

@@ -74,9 +74,6 @@ static void hw_delay_complete(struct timer_list *t)
 
 static void mock_context_unpin(struct intel_context *ce)
 {
-	if (--ce->pin_count)
-		return;
-
 	i915_gem_context_put(ce->gem_context);
 }