drm/i915: Integrate i915_sw_fence with debugobjects

Add the tracking required to enable debugobjects for fences to improve
error detection in BAT. The debugobject interface lets us track the
lifetime and phases of the fences even while being embedded into larger
structs, i.e. to check they are not used after they have been released.

v2: Don't populate the stubs, debugobjects checks for a NULL pointer and
treats it equivalently.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161125131718.20978-4-chris@chris-wilson.co.uk

1 files changed, 133 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index 147420ccf49c..f5a88092dacf 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -17,6 +17,92 @@
 
 static DEFINE_SPINLOCK(i915_sw_fence_lock);
 
+enum {
+	DEBUG_FENCE_IDLE = 0,
+	DEBUG_FENCE_NOTIFY,
+};
+
+#ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
+
+static void *i915_sw_fence_debug_hint(void *addr)
+{
+	return (void *)(((struct i915_sw_fence *)addr)->flags & I915_SW_FENCE_MASK);
+}
+
+static struct debug_obj_descr i915_sw_fence_debug_descr = {
+	.name = "i915_sw_fence",
+	.debug_hint = i915_sw_fence_debug_hint,
+};
+
+static inline void debug_fence_init(struct i915_sw_fence *fence)
+{
+	debug_object_init(fence, &i915_sw_fence_debug_descr);
+}
+
+static inline void debug_fence_activate(struct i915_sw_fence *fence)
+{
+	debug_object_activate(fence, &i915_sw_fence_debug_descr);
+}
+
+static inline void debug_fence_set_state(struct i915_sw_fence *fence,
+					 int old, int new)
+{
+	debug_object_active_state(fence, &i915_sw_fence_debug_descr, old, new);
+}
+
+static inline void debug_fence_deactivate(struct i915_sw_fence *fence)
+{
+	debug_object_deactivate(fence, &i915_sw_fence_debug_descr);
+}
+
+static inline void debug_fence_destroy(struct i915_sw_fence *fence)
+{
+	debug_object_destroy(fence, &i915_sw_fence_debug_descr);
+}
+
+static inline void debug_fence_free(struct i915_sw_fence *fence)
+{
+	debug_object_free(fence, &i915_sw_fence_debug_descr);
+}
+
+static inline void debug_fence_assert(struct i915_sw_fence *fence)
+{
+	debug_object_assert_init(fence, &i915_sw_fence_debug_descr);
+}
+
+#else
+
+static inline void debug_fence_init(struct i915_sw_fence *fence)
+{
+}
+
+static inline void debug_fence_activate(struct i915_sw_fence *fence)
+{
+}
+
+static inline void debug_fence_set_state(struct i915_sw_fence *fence,
+					 int old, int new)
+{
+}
+
+static inline void debug_fence_deactivate(struct i915_sw_fence *fence)
+{
+}
+
+static inline void debug_fence_destroy(struct i915_sw_fence *fence)
+{
+}
+
+static inline void debug_fence_free(struct i915_sw_fence *fence)
+{
+}
+
+static inline void debug_fence_assert(struct i915_sw_fence *fence)
+{
+}
+
+#endif
+
 static int __i915_sw_fence_notify(struct i915_sw_fence *fence,
 				  enum i915_sw_fence_notify state)
 {
@@ -26,25 +112,37 @@ static int __i915_sw_fence_notify(struct i915_sw_fence *fence,
 	return fn(fence, state);
 }
 
-static void i915_sw_fence_free(struct kref *kref)
+#ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
+void i915_sw_fence_fini(struct i915_sw_fence *fence)
+{
+	debug_fence_free(fence);
+}
+#endif
+
+static void i915_sw_fence_release(struct kref *kref)
 {
 	struct i915_sw_fence *fence = container_of(kref, typeof(*fence), kref);
 
 	WARN_ON(atomic_read(&fence->pending) > 0);
+	debug_fence_destroy(fence);
 
-	if (fence->flags & I915_SW_FENCE_MASK)
+	if (fence->flags & I915_SW_FENCE_MASK) {
 		__i915_sw_fence_notify(fence, FENCE_FREE);
-	else
+	} else {
+		i915_sw_fence_fini(fence);
 		kfree(fence);
+	}
 }
 
 static void i915_sw_fence_put(struct i915_sw_fence *fence)
 {
-	kref_put(&fence->kref, i915_sw_fence_free);
+	debug_fence_assert(fence);
+	kref_put(&fence->kref, i915_sw_fence_release);
 }
 
 static struct i915_sw_fence *i915_sw_fence_get(struct i915_sw_fence *fence)
 {
+	debug_fence_assert(fence);
 	kref_get(&fence->kref);
 	return fence;
 }
@@ -56,6 +154,7 @@ static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
 	wait_queue_t *pos, *next;
 	unsigned long flags;
 
+	debug_fence_deactivate(fence);
 	atomic_set_release(&fence->pending, -1); /* 0 -> -1 [done] */
 
 	/*
@@ -88,23 +187,33 @@ static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
 		} while (1);
 	}
 	spin_unlock_irqrestore(&x->lock, flags);
+
+	debug_fence_assert(fence);
 }
 
 static void __i915_sw_fence_complete(struct i915_sw_fence *fence,
 				     struct list_head *continuation)
 {
+	debug_fence_assert(fence);
+
 	if (!atomic_dec_and_test(&fence->pending))
 		return;
 
+	debug_fence_set_state(fence, DEBUG_FENCE_IDLE, DEBUG_FENCE_NOTIFY);
+
 	if (fence->flags & I915_SW_FENCE_MASK &&
 	    __i915_sw_fence_notify(fence, FENCE_COMPLETE) != NOTIFY_DONE)
 		return;
 
+	debug_fence_set_state(fence, DEBUG_FENCE_NOTIFY, DEBUG_FENCE_IDLE);
+
 	__i915_sw_fence_wake_up_all(fence, continuation);
 }
 
 static void i915_sw_fence_complete(struct i915_sw_fence *fence)
 {
+	debug_fence_assert(fence);
+
 	if (WARN_ON(i915_sw_fence_done(fence)))
 		return;
 
@@ -113,6 +222,7 @@ static void i915_sw_fence_complete(struct i915_sw_fence *fence)
 
 static void i915_sw_fence_await(struct i915_sw_fence *fence)
 {
+	debug_fence_assert(fence);
 	WARN_ON(atomic_inc_return(&fence->pending) <= 1);
 }
 
@@ -123,18 +233,26 @@ void __i915_sw_fence_init(struct i915_sw_fence *fence,
 {
 	BUG_ON((unsigned long)fn & ~I915_SW_FENCE_MASK);
 
+	debug_fence_init(fence);
+
 	__init_waitqueue_head(&fence->wait, name, key);
 	kref_init(&fence->kref);
 	atomic_set(&fence->pending, 1);
 	fence->flags = (unsigned long)fn;
 }
 
-void i915_sw_fence_commit(struct i915_sw_fence *fence)
+static void __i915_sw_fence_commit(struct i915_sw_fence *fence)
 {
 	i915_sw_fence_complete(fence);
 	i915_sw_fence_put(fence);
 }
 
+void i915_sw_fence_commit(struct i915_sw_fence *fence)
+{
+	debug_fence_activate(fence);
+	__i915_sw_fence_commit(fence);
+}
+
 static int i915_sw_fence_wake(wait_queue_t *wq, unsigned mode, int flags, void *key)
 {
 	list_del(&wq->task_list);
@@ -206,9 +324,13 @@ static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 	unsigned long flags;
 	int pending;
 
+	debug_fence_assert(fence);
+
 	if (i915_sw_fence_done(signaler))
 		return 0;
 
+	debug_fence_assert(signaler);
+
 	/* The dependency graph must be acyclic. */
 	if (unlikely(i915_sw_fence_check_if_after(fence, signaler)))
 		return -EINVAL;
@@ -279,7 +401,7 @@ static void timer_i915_sw_fence_wake(unsigned long data)
 	dma_fence_put(cb->dma);
 	cb->dma = NULL;
 
-	i915_sw_fence_commit(cb->fence);
+	__i915_sw_fence_commit(cb->fence);
 	cb->timer.function = NULL;
 }
 
@@ -290,7 +412,7 @@ static void dma_i915_sw_fence_wake(struct dma_fence *dma,
 
 	del_timer_sync(&cb->timer);
 	if (cb->timer.function)
-		i915_sw_fence_commit(cb->fence);
+		__i915_sw_fence_commit(cb->fence);
 	dma_fence_put(cb->dma);
 
 	kfree(cb);
@@ -304,6 +426,8 @@ int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
 	struct i915_sw_dma_fence_cb *cb;
 	int ret;
 
+	debug_fence_assert(fence);
+
 	if (dma_fence_is_signaled(dma))
 		return 0;
 
@@ -349,6 +473,8 @@ int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
 	struct dma_fence *excl;
 	int ret = 0, pending;
 
+	debug_fence_assert(fence);
+
 	if (write) {
 		struct dma_fence **shared;
 		unsigned int count, i;