drm/i915: Provide an i915_active.acquire callback

If we introduce a callback for i915_active that is only called the first
time we use the i915_active and is symmetrically paired with the
i915_active.retire callback, we can replace the open-coded and
non-atomic implementations -- which will be very fragile (i.e. broken)
upon removing the struct_mutex serialisation.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190621183801.23252-4-chris@chris-wilson.co.uk

1 files changed, 30 insertions, 35 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 23120901c55f..938dd032b820 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -95,11 +95,15 @@ void intel_context_unpin(struct intel_context *ce)
 	intel_context_put(ce);
 }
 
-static int __context_pin_state(struct i915_vma *vma, unsigned long flags)
+static int __context_pin_state(struct i915_vma *vma)
 {
+	u64 flags;
 	int err;
 
-	err = i915_vma_pin(vma, 0, 0, flags | PIN_GLOBAL);
+	flags = i915_ggtt_pin_bias(vma) | PIN_OFFSET_BIAS;
+	flags |= PIN_HIGH | PIN_GLOBAL;
+
+	err = i915_vma_pin(vma, 0, 0, flags);
 	if (err)
 		return err;
 
@@ -119,7 +123,7 @@ static void __context_unpin_state(struct i915_vma *vma)
 	__i915_vma_unpin(vma);
 }
 
-static void intel_context_retire(struct i915_active *active)
+static void __intel_context_retire(struct i915_active *active)
 {
 	struct intel_context *ce = container_of(active, typeof(*ce), active);
 
@@ -130,35 +134,11 @@ static void intel_context_retire(struct i915_active *active)
 	intel_context_put(ce);
 }
 
-void
-intel_context_init(struct intel_context *ce,
-		   struct i915_gem_context *ctx,
-		   struct intel_engine_cs *engine)
-{
-	GEM_BUG_ON(!engine->cops);
-
-	kref_init(&ce->ref);
-
-	ce->gem_context = ctx;
-	ce->engine = engine;
-	ce->ops = engine->cops;
-	ce->sseu = engine->sseu;
-
-	INIT_LIST_HEAD(&ce->signal_link);
-	INIT_LIST_HEAD(&ce->signals);
-
-	mutex_init(&ce->pin_mutex);
-
-	i915_active_init(ctx->i915, &ce->active, intel_context_retire);
-}
-
-int intel_context_active_acquire(struct intel_context *ce, unsigned long flags)
+static int __intel_context_active(struct i915_active *active)
 {
+	struct intel_context *ce = container_of(active, typeof(*ce), active);
 	int err;
 
-	if (!i915_active_acquire(&ce->active))
-		return 0;
-
 	intel_context_get(ce);
 
 	err = intel_ring_pin(ce->ring);
@@ -168,7 +148,7 @@ int intel_context_active_acquire(struct intel_context *ce, unsigned long flags)
 	if (!ce->state)
 		return 0;
 
-	err = __context_pin_state(ce->state, flags);
+	err = __context_pin_state(ce->state);
 	if (err)
 		goto err_ring;
 
@@ -188,15 +168,30 @@ err_ring:
 	intel_ring_unpin(ce->ring);
 err_put:
 	intel_context_put(ce);
-	i915_active_cancel(&ce->active);
 	return err;
 }
 
-void intel_context_active_release(struct intel_context *ce)
+void
+intel_context_init(struct intel_context *ce,
+		   struct i915_gem_context *ctx,
+		   struct intel_engine_cs *engine)
 {
-	/* Nodes preallocated in intel_context_active() */
-	i915_active_acquire_barrier(&ce->active);
-	i915_active_release(&ce->active);
+	GEM_BUG_ON(!engine->cops);
+
+	kref_init(&ce->ref);
+
+	ce->gem_context = ctx;
+	ce->engine = engine;
+	ce->ops = engine->cops;
+	ce->sseu = engine->sseu;
+
+	INIT_LIST_HEAD(&ce->signal_link);
+	INIT_LIST_HEAD(&ce->signals);
+
+	mutex_init(&ce->pin_mutex);
+
+	i915_active_init(ctx->i915, &ce->active,
+			 __intel_context_active, __intel_context_retire);
 }
 
 static void i915_global_context_shrink(void)