[Intel-gfx] [PATCH] drm/i915: Remove nest annotation from intel_context_unpin

[Maarten Lankhorst]

Lets see what breaks, round 3?

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/gpu/drm/i915/gt/intel_context.c       | 27 +++++++++++++------
 drivers/gpu/drm/i915/gt/intel_context_types.h |  1 +
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index fbaa9df6f436..671049695e6b 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -47,21 +47,30 @@ int __intel_context_do_pin(struct intel_context *ce)
 {
 	int err;
 
-	if (mutex_lock_interruptible(&ce->pin_mutex))
-		return -EINTR;
-
-	if (likely(!atomic_read(&ce->pin_count))) {
-		intel_wakeref_t wakeref;
+	if (unlikely(!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))) {
+		err = mutex_lock_interruptible(&ce->alloc_mutex);
+		if (err)
+			return err;
 
-		if (unlikely(!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))) {
+		if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags)) {
 			err = ce->ops->alloc(ce);
 			if (unlikely(err))
 				goto err;
 
+			smp_mb(); /* Make sure allocation is flushed to memory */
+
 			__set_bit(CONTEXT_ALLOC_BIT, &ce->flags);
 		}
+		mutex_unlock(&ce->alloc_mutex);
+	}
+
+	err = mutex_lock_interruptible(&ce->pin_mutex);
+	if (err)
+		return err;
+
+	if (likely(!atomic_read(&ce->pin_count))) {
+		intel_wakeref_t wakeref;
 
-		err = 0;
 		with_intel_runtime_pm(ce->engine->uncore->rpm, wakeref)
 			err = ce->ops->pin(ce);
 		if (err)
@@ -91,7 +100,7 @@ void intel_context_unpin(struct intel_context *ce)
 
 	/* We may be called from inside intel_context_pin() to evict another */
 	intel_context_get(ce);
-	mutex_lock_nested(&ce->pin_mutex, SINGLE_DEPTH_NESTING);
+	mutex_lock(&ce->pin_mutex);
 
 	if (likely(atomic_dec_and_test(&ce->pin_count))) {
 		CE_TRACE(ce, "retire\n");
@@ -228,6 +237,7 @@ intel_context_init(struct intel_context *ce,
 	INIT_LIST_HEAD(&ce->signals);
 
 	mutex_init(&ce->pin_mutex);
+	mutex_init(&ce->alloc_mutex);
 
 	i915_active_init(&ce->active,
 			 __intel_context_active, __intel_context_retire);
@@ -239,6 +249,7 @@ void intel_context_fini(struct intel_context *ce)
 		intel_timeline_put(ce->timeline);
 	i915_vm_put(ce->vm);
 
+	mutex_destroy(&ce->alloc_mutex);
 	mutex_destroy(&ce->pin_mutex);
 	i915_active_fini(&ce->active);
 }
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index ca1420fb8b53..abae296980fa 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -72,6 +72,7 @@ struct intel_context {
 
 	atomic_t pin_count;
 	struct mutex pin_mutex; /* guards pinning and associated on-gpuing */
+	struct mutex alloc_mutex; /* guards against concurrent contex allocation */
 
 	/**
 	 * active: Active tracker for the rq activity (inc. external) on this
-- 
2.24.1