[PATCH 5/5] remove pin_mutex try1, naively

[Maarten Lankhorst]

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/gpu/drm/i915/gt/intel_context.c | 49 +++++++++----------------
 drivers/gpu/drm/i915/gt/intel_context.h | 13 +++++--
 2 files changed, 27 insertions(+), 35 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 4033184f13b9..b1ccab2fad2e 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -53,24 +53,26 @@ int intel_context_alloc_state(struct intel_context *ce)
 {
 	int err = 0;
 
-	if (mutex_lock_interruptible(&ce->pin_mutex))
-		return -EINTR;
-
-	if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags)) {
-		if (intel_context_is_banned(ce)) {
-			err = -EIO;
-			goto unlock;
-		}
+	if (test_bit(CONTEXT_ALLOC_BIT, &ce->flags))
+		return 0;
 
-		err = ce->ops->alloc(ce);
-		if (unlikely(err))
-			goto unlock;
+	err = i915_gem_object_lock_interruptible(ce->timeline->hwsp_ggtt->obj, NULL);
+	if (err)
+		return err;
 
-		set_bit(CONTEXT_ALLOC_BIT, &ce->flags);
+	if (intel_context_is_banned(ce)) {
+		err = -EIO;
+		goto unlock;
 	}
 
+	err = ce->ops->alloc(ce);
+	if (unlikely(err))
+		goto unlock;
+
+	set_bit(CONTEXT_ALLOC_BIT, &ce->flags);
+
 unlock:
-	mutex_unlock(&ce->pin_mutex);
+	i915_gem_object_unlock(ce->timeline->hwsp_ggtt->obj);
 	return err;
 }
 
@@ -213,12 +215,6 @@ int __intel_context_do_pin_ww(struct intel_context *ce,
 			return err;
 	}
 
-	/*
-	 * We always pin the context/ring/timeline here, to ensure a pin
-	 * refcount for __intel_context_active(), which prevent a lock
-	 * inversion of ce->pin_mutex vs dma_resv_lock().
-	 */
-
 	err = i915_gem_object_lock(ce->timeline->hwsp_ggtt->obj, ww);
 	if (!err && ce->ring->vma->obj)
 		err = i915_gem_object_lock(ce->ring->vma->obj, ww);
@@ -237,24 +233,20 @@ int __intel_context_do_pin_ww(struct intel_context *ce,
 	if (err)
 		goto err_release;
 
-	err = mutex_lock_interruptible(&ce->pin_mutex);
-	if (err)
-		goto err_post_unpin;
-
 	if (unlikely(intel_context_is_closed(ce))) {
 		err = -ENOENT;
-		goto err_unlock;
+		goto err_post_unpin;
 	}
 
 	if (likely(!atomic_add_unless(&ce->pin_count, 1, 0))) {
 		err = intel_context_active_acquire(ce);
 		if (unlikely(err))
-			goto err_unlock;
+			goto err_post_unpin;
 
 		err = ce->ops->pin(ce, vaddr);
 		if (err) {
 			intel_context_active_release(ce);
-			goto err_unlock;
+			goto err_post_unpin;
 		}
 
 		CE_TRACE(ce, "pin ring:{start:%08x, head:%04x, tail:%04x}\n",
@@ -268,8 +260,6 @@ int __intel_context_do_pin_ww(struct intel_context *ce,
 
 	GEM_BUG_ON(!intel_context_is_pinned(ce)); /* no overflow! */
 
-err_unlock:
-	mutex_unlock(&ce->pin_mutex);
 err_post_unpin:
 	if (!handoff)
 		ce->ops->post_unpin(ce);
@@ -381,8 +371,6 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
 	spin_lock_init(&ce->signal_lock);
 	INIT_LIST_HEAD(&ce->signals);
 
-	mutex_init(&ce->pin_mutex);
-
 	i915_active_init(&ce->active,
 			 __intel_context_active, __intel_context_retire, 0);
 }
@@ -393,7 +381,6 @@ void intel_context_fini(struct intel_context *ce)
 		intel_timeline_put(ce->timeline);
 	i915_vm_put(ce->vm);
 
-	mutex_destroy(&ce->pin_mutex);
 	i915_active_fini(&ce->active);
 }
 
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index f83a73a2b39f..0de56c50e828 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -49,9 +49,14 @@ int intel_context_reconfigure_sseu(struct intel_context *ce,
  * intel_context_is_pinned() remains stable.
  */
 static inline int intel_context_lock_pinned(struct intel_context *ce)
-	__acquires(ce->pin_mutex)
+	__acquires(&ce->state->obj->base.resv->lock)
 {
-	return mutex_lock_interruptible(&ce->pin_mutex);
+	int ret = intel_context_alloc_state(ce);
+
+	if (ret)
+		return ret;
+
+	return i915_gem_object_lock_interruptible(ce->state->obj, NULL);
 }
 
 /**
@@ -76,9 +81,9 @@ intel_context_is_pinned(struct intel_context *ce)
  * Releases the lock earlier acquired by intel_context_unlock_pinned().
  */
 static inline void intel_context_unlock_pinned(struct intel_context *ce)
-	__releases(ce->pin_mutex)
+	__releases(&ce->state->obj->base.resv->lock)
 {
-	mutex_unlock(&ce->pin_mutex);
+	i915_gem_object_unlock(ce->state->obj);
 }
 
 int __intel_context_do_pin(struct intel_context *ce);
-- 
2.31.0