 @@ -1,1013 +1,1014 @@
-/*	$NetBSD: i915_active.c,v 1.10 2021/12/24 00:14:03 riastradh Exp $	*/
+/*	$NetBSD: i915_active.c,v 1.11 2022/02/14 20:37:51 riastradh Exp $	*/
 /*
  * SPDX-License-Identifier: MIT
+ *
  * Copyright © 2019 Intel Corporation
  */
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: i915_active.c,v 1.10 2021/12/24 00:14:03 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: i915_active.c,v 1.11 2022/02/14 20:37:51 riastradh Exp $");
 #include <linux/debugobjects.h>
 #include "gt/intel_context.h"
 #include "gt/intel_engine_pm.h"
 #include "gt/intel_ring.h"
 #include "i915_drv.h"
 #include "i915_active.h"
 #include "i915_globals.h"
 #include <linux/nbsd-namespace.h>
 /*
  * Active refs memory management
+ *
  * To be more economical with memory, we reap all the i915_active trees as
  * they idle (when we know the active requests are inactive) and allocate the
  * nodes from a local slab cache to hopefully reduce the fragmentation.
  */
 static struct i915_global_active {
 	struct i915_global base;
 	struct kmem_cache *slab_cache;
 } global;
 struct active_node {
 	struct i915_active_fence base;
 	struct i915_active *ref;
 	struct rb_node node;
 	u64 timeline;
 	struct intel_engine_cs *engine;
 };
 static inline struct active_node *
 node_from_active(struct i915_active_fence *active)
+{
 	return container_of(active, struct active_node, base);
+}
 #define take_preallocated_barriers(x) llist_del_all(&(x)->preallocated_barriers)
 static inline bool is_barrier(const struct i915_active_fence *active)
+{
 	return IS_ERR(rcu_access_pointer(active->fence));
+}
 static inline struct llist_node *barrier_to_ll(struct active_node *node)
+{
 	GEM_BUG_ON(!is_barrier(&node->base));
 	return &node->base.llist;
+}
 static inline struct intel_engine_cs *
 __barrier_to_engine(struct active_node *node)
+{
 	return READ_ONCE(node->engine);
+}
 static inline struct intel_engine_cs *
 barrier_to_engine(struct active_node *node)
+{
 	GEM_BUG_ON(!is_barrier(&node->base));
 	return __barrier_to_engine(node);
+}
 static inline struct active_node *barrier_from_ll(struct llist_node *x)
+{
 	return container_of(x, struct active_node, base.llist);
+}
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM) && IS_ENABLED(CONFIG_DEBUG_OBJECTS)
 static void *active_debug_hint(void *addr)
+{
 	struct i915_active *ref = addr;
 	return (void *)ref->active ?: (void *)ref->retire ?: (void *)ref;
+}
 static struct debug_obj_descr active_debug_desc = {
 	.name = "i915_active",
 	.debug_hint = active_debug_hint,
 };
 static void debug_active_init(struct i915_active *ref)
+{
 	debug_object_init(ref, &active_debug_desc);
+}
 static void debug_active_activate(struct i915_active *ref)
+{
 	lockdep_assert_held(&ref->tree_lock);
 	if (!atomic_read(&ref->count)) /* before the first inc */
 		debug_object_activate(ref, &active_debug_desc);
+}
 static void debug_active_deactivate(struct i915_active *ref)
+{
 	lockdep_assert_held(&ref->tree_lock);
 	if (!atomic_read(&ref->count)) /* after the last dec */
 		debug_object_deactivate(ref, &active_debug_desc);
+}
 static void debug_active_fini(struct i915_active *ref)
+{
 	debug_object_free(ref, &active_debug_desc);
+}
 static void debug_active_assert(struct i915_active *ref)
+{
 	debug_object_assert_init(ref, &active_debug_desc);
+}
 #else
 static inline void debug_active_init(struct i915_active *ref) { }
 static inline void debug_active_activate(struct i915_active *ref) { }
 static inline void debug_active_deactivate(struct i915_active *ref) { }
 static inline void debug_active_fini(struct i915_active *ref) { }
 static inline void debug_active_assert(struct i915_active *ref) { }
 #endif
 #ifdef __NetBSD__
 static int
 compare_nodes(void *cookie, const void *va, const void *vb)
+{
 	const struct active_node *a = va;
 	const struct active_node *b = vb;
 	if (a->timeline < b->timeline)
 		return -1;
 	if (a->timeline > b->timeline)
 		return +1;
 	if ((uintptr_t)a < (uintptr_t)b)
 		return -1;
 	if ((uintptr_t)a > (uintptr_t)b)
 		return +1;
 	return 0;
+}
 static int
 compare_node_key(void *cookie, const void *vn, const void *vk)
+{
 	const struct active_node *a = vn;
 	const uint64_t *k = vk;
 	if (a->timeline < *k)
 		return -1;
 	if (a->timeline > *k)
 		return +1;
 	return 0;
+}
 static const rb_tree_ops_t active_rb_ops = {
 	.rbto_compare_nodes = compare_nodes,
 	.rbto_compare_key = compare_node_key,
 	.rbto_node_offset = offsetof(struct active_node, node),
 };
 #endif
 static void
 __active_retire(struct i915_active *ref)
+{
 	struct active_node *it, *n;
 	struct rb_root root;
 	unsigned long flags;
 	GEM_BUG_ON(i915_active_is_idle(ref));
 	/* return the unused nodes to our slabcache -- flushing the allocator */
 	if (!atomic_dec_and_lock_irqsave(&ref->count, &ref->tree_lock, flags))
 		return;
 	GEM_BUG_ON(rcu_access_pointer(ref->excl.fence));
 	debug_active_deactivate(ref);
 	root = ref->tree;
 #ifdef __NetBSD__
 	rb_tree_init(&ref->tree.rbr_tree, &active_rb_ops);
 #else
 	ref->tree = RB_ROOT;
 #endif
 	ref->cache = NULL;
 	DRM_SPIN_WAKEUP_ALL(&ref->tree_wq, &ref->tree_lock);
 	spin_unlock_irqrestore(&ref->tree_lock, flags);
 	/* After the final retire, the entire struct may be freed */
 	if (ref->retire)
 		ref->retire(ref);
 	/* ... except if you wait on it, you must manage your own references! */
 	spin_lock(&ref->tree_lock);
 	DRM_SPIN_WAKEUP_ALL(&ref->tree_wq, &ref->tree_lock);
 	spin_unlock(&ref->tree_lock);
 	rbtree_postorder_for_each_entry_safe(it, n, &root, node) {
 		GEM_BUG_ON(i915_active_fence_isset(&it->base));
 		kmem_cache_free(global.slab_cache, it);
+	}
+}
 static void
 active_work(struct work_struct *wrk)
+{
 	struct i915_active *ref = container_of(wrk, typeof(*ref), work);
 	GEM_BUG_ON(!atomic_read(&ref->count));
 	if (atomic_add_unless(&ref->count, -1, 1))
 		return;
 	__active_retire(ref);
+}
 static void
 active_retire(struct i915_active *ref)
+{
 	GEM_BUG_ON(!atomic_read(&ref->count));
 	if (atomic_add_unless(&ref->count, -1, 1))
 		return;
 	if (ref->flags & I915_ACTIVE_RETIRE_SLEEPS) {
 		queue_work(system_unbound_wq, &ref->work);
 		return;
+	}
 	__active_retire(ref);
+}
 static inline struct dma_fence **
 __active_fence_slot(struct i915_active_fence *active)
+{
 	return (struct dma_fence ** __force)&active->fence;
+}
 static inline bool
 active_fence_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
+{
 	struct i915_active_fence *active =
 		container_of(cb, typeof(*active), cb);
 	return cmpxchg(__active_fence_slot(active), fence, NULL) == fence;
+}
 static void
 node_retire(struct dma_fence *fence, struct dma_fence_cb *cb)
+{
 	if (active_fence_cb(fence, cb))
 		active_retire(container_of(cb, struct active_node, base.cb)->ref);
+}
 static void
 excl_retire(struct dma_fence *fence, struct dma_fence_cb *cb)
+{
 	if (active_fence_cb(fence, cb))
 		active_retire(container_of(cb, struct i915_active, excl.cb));
+}
 static struct i915_active_fence *
 active_instance(struct i915_active *ref, struct intel_timeline *tl)
+{
 	struct active_node *node, *prealloc;
 	struct rb_node **p, *parent;
 	u64 idx = tl->fence_context;
 	/*
 	 * We track the most recently used timeline to skip a rbtree search
 	 * for the common case, under typical loads we never need the rbtree
 	 * at all. We can reuse the last slot if it is empty, that is
 	 * after the previous activity has been retired, or if it matches the
 	 * current timeline.
 	 */
 	node = READ_ONCE(ref->cache);
 	if (node && node->timeline == idx)
 		return &node->base;
 	/* Preallocate a replacement, just in case */
 	prealloc = kmem_cache_alloc(global.slab_cache, GFP_KERNEL);
 	if (!prealloc)
 		return NULL;
 	memset(prealloc, 0, sizeof(*prealloc));
 	spin_lock_irq(&ref->tree_lock);
 	GEM_BUG_ON(i915_active_is_idle(ref));
 #ifdef __NetBSD__
 	__USE(parent);
 	__USE(p);
 	node = rb_tree_find_node(&ref->tree.rbr_tree, &idx);
 	if (node) {
 		KASSERT(node->timeline == idx);
 		kmem_cache_free(global.slab_cache, prealloc);
 		goto out;
+	}
 #else
 	parent = NULL;
 	p = &ref->tree.rb_node;
 	while (*p) {
 		parent = *p;
 		node = rb_entry(parent, struct active_node, node);
 		if (node->timeline == idx) {
 			kmem_cache_free(global.slab_cache, prealloc);
 			goto out;
+		}
 		if (node->timeline < idx)
 			p = &parent->rb_right;
 		else
 			p = &parent->rb_left;
+	}
 #endif
 	node = prealloc;
 	__i915_active_fence_init(&node->base, NULL, node_retire);
 	node->ref = ref;
 	node->timeline = idx;
 #ifdef __NetBSD__
 	struct active_node *collision __diagused;
 	collision = rb_tree_insert_node(&ref->tree.rbr_tree, node);
 	KASSERT(collision == node);
 #else
 	rb_link_node(&node->node, parent, p);
 	rb_insert_color(&node->node, &ref->tree);
 #endif
 out:
 	ref->cache = node;
 	spin_unlock_irq(&ref->tree_lock);
 	BUILD_BUG_ON(offsetof(typeof(*node), base));
 	return &node->base;
+}
 void __i915_active_init(struct i915_active *ref,
 			int (*active)(struct i915_active *ref),
 			void (*retire)(struct i915_active *ref),
 			struct lock_class_key *mkey,
 			struct lock_class_key *wkey)
+{
 	unsigned long bits;
 	debug_active_init(ref);
 	ref->flags = 0;
 	ref->active = active;
 	ref->retire = ptr_unpack_bits(retire, &bits, 2);
 	if (bits & I915_ACTIVE_MAY_SLEEP)
 		ref->flags |= I915_ACTIVE_RETIRE_SLEEPS;
 	spin_lock_init(&ref->tree_lock);
 	DRM_INIT_WAITQUEUE(&ref->tree_wq, "i915act");
 #ifdef __NetBSD__
 	rb_tree_init(&ref->tree.rbr_tree, &active_rb_ops);
 #else
 	ref->tree = RB_ROOT;
 #endif
 	ref->cache = NULL;
 	init_llist_head(&ref->preallocated_barriers);
 	atomic_set(&ref->count, 0);
 	__mutex_init(&ref->mutex, "i915_active", mkey);
 	__i915_active_fence_init(&ref->excl, NULL, excl_retire);
 	INIT_WORK(&ref->work, active_work);
 #if IS_ENABLED(CONFIG_LOCKDEP)
 	lockdep_init_map(&ref->work.lockdep_map, "i915_active.work", wkey, 0);
 #endif
+}
 static bool ____active_del_barrier(struct i915_active *ref,
 				   struct active_node *node,
 				   struct intel_engine_cs *engine)
+{
 	struct llist_node *head = NULL, *tail = NULL;
 	struct llist_node *pos, *next;
 	GEM_BUG_ON(node->timeline != engine->kernel_context->timeline->fence_context);
 	/*
 	 * Rebuild the llist excluding our node. We may perform this
 	 * outside of the kernel_context timeline mutex and so someone
 	 * else may be manipulating the engine->barrier_tasks, in
 	 * which case either we or they will be upset :)
+	 *
 	 * A second __active_del_barrier() will report failure to claim
 	 * the active_node and the caller will just shrug and know not to
 	 * claim ownership of its node.
+	 *
 	 * A concurrent i915_request_add_active_barriers() will miss adding
 	 * any of the tasks, but we will try again on the next -- and since
 	 * we are actively using the barrier, we know that there will be
 	 * at least another opportunity when we idle.
 	 */
 	llist_for_each_safe(pos, next, llist_del_all(&engine->barrier_tasks)) {
 		if (node == barrier_from_ll(pos)) {
 			node = NULL;
 			continue;
+		}
 		pos->next = head;
 		head = pos;
 		if (!tail)
 			tail = pos;
+	}
 	if (head)
 		llist_add_batch(head, tail, &engine->barrier_tasks);
 	return !node;
+}
 static bool
 __active_del_barrier(struct i915_active *ref, struct active_node *node)
+{
 	return ____active_del_barrier(ref, node, barrier_to_engine(node));
+}
 int i915_active_ref(struct i915_active *ref,
 		    struct intel_timeline *tl,
 		    struct dma_fence *fence)
+{
 	struct i915_active_fence *active;
 	int err;
 	lockdep_assert_held(&tl->mutex);
 	/* Prevent reaping in case we malloc/wait while building the tree */
 	err = i915_active_acquire(ref);
 	if (err)
 		return err;
 	active = active_instance(ref, tl);
 	if (!active) {
 		err = -ENOMEM;
 		goto out;
+	}
 	if (is_barrier(active)) { /* proto-node used by our idle barrier */
 		/*
 		 * This request is on the kernel_context timeline, and so
 		 * we can use it to substitute for the pending idle-barrer
 		 * request that we want to emit on the kernel_context.
 		 */
 		__active_del_barrier(ref, node_from_active(active));
 		RCU_INIT_POINTER(active->fence, NULL);
 		atomic_dec(&ref->count);
+	}
 	if (!__i915_active_fence_set(active, fence))
 		atomic_inc(&ref->count);
 out:
 	i915_active_release(ref);
 	return err;
+}
 void i915_active_set_exclusive(struct i915_active *ref, struct dma_fence *f)
+{
 	/* We expect the caller to manage the exclusive timeline ordering */
 	GEM_BUG_ON(i915_active_is_idle(ref));
 	if (!__i915_active_fence_set(&ref->excl, f))
 		atomic_inc(&ref->count);
+}
 bool i915_active_acquire_if_busy(struct i915_active *ref)
+{
 	debug_active_assert(ref);
 	return atomic_add_unless(&ref->count, 1, 0);
+}
 int i915_active_acquire(struct i915_active *ref)
+{
 	int err;
 	if (i915_active_acquire_if_busy(ref))
 		return 0;
 	err = mutex_lock_interruptible(&ref->mutex);
 	if (err)
 		return err;
 	if (likely(!i915_active_acquire_if_busy(ref))) {
 		if (ref->active)
 			err = ref->active(ref);
 		if (!err) {
 			spin_lock_irq(&ref->tree_lock); /* __active_retire() */
 			debug_active_activate(ref);
 			atomic_inc(&ref->count);
 			spin_unlock_irq(&ref->tree_lock);
+		}
+	}
 	mutex_unlock(&ref->mutex);
 	return err;
+}
 void i915_active_release(struct i915_active *ref)
+{
 	debug_active_assert(ref);
 	active_retire(ref);
+}
 static void enable_signaling(struct i915_active_fence *active)
+{
 	struct dma_fence *fence;
 	fence = i915_active_fence_get(active);
 	if (!fence)
 		return;
 	dma_fence_enable_sw_signaling(fence);
 	dma_fence_put(fence);
+}
 int i915_active_wait(struct i915_active *ref)
+{
 	struct active_node *it, *n;
 	int err = 0;
 	might_sleep();
 	if (!i915_active_acquire_if_busy(ref))
 		return 0;
 	/* Flush lazy signals */
 	enable_signaling(&ref->excl);
 	rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
 		if (is_barrier(&it->base)) /* unconnected idle barrier */
 			continue;
 		enable_signaling(&it->base);
+	}
 	/* Any fence added after the wait begins will not be auto-signaled */
 	i915_active_release(ref);
 	if (err)
 		return err;
 	spin_lock(&ref->tree_lock);
 	DRM_SPIN_WAIT_UNTIL(err, &ref->tree_wq, &ref->tree_lock,
 	    i915_active_is_idle(ref));
 	spin_unlock(&ref->tree_lock);
 	if (err)
 		return err;
 	flush_work(&ref->work);
 	return 0;
+}
 int i915_request_await_active(struct i915_request *rq, struct i915_active *ref)
+{
 	int err = 0;
 	if (rcu_access_pointer(ref->excl.fence)) {
 		struct dma_fence *fence;
 		rcu_read_lock();
 		fence = dma_fence_get_rcu_safe(&ref->excl.fence);
 		rcu_read_unlock();
 		if (fence) {
 			err = i915_request_await_dma_fence(rq, fence);
 			dma_fence_put(fence);
+		}
+	}
 	/* In the future we may choose to await on all fences */
 	return err;
+}
 void i915_active_fini(struct i915_active *ref)
+{
 	debug_active_fini(ref);
 	GEM_BUG_ON(atomic_read(&ref->count));
 	GEM_BUG_ON(work_pending(&ref->work));
 	GEM_BUG_ON(!RB_EMPTY_ROOT(&ref->tree));
 	mutex_destroy(&ref->mutex);
 	spin_lock_destroy(&ref->tree_lock);
+}
 static inline bool is_idle_barrier(struct active_node *node, u64 idx)
+{
 	return node->timeline == idx && !i915_active_fence_isset(&node->base);
+}
 static struct active_node *reuse_idle_barrier(struct i915_active *ref, u64 idx)
+{
 	struct rb_node *prev, *p;
 	if (RB_EMPTY_ROOT(&ref->tree))
 		return NULL;
 	spin_lock_irq(&ref->tree_lock);
 	GEM_BUG_ON(i915_active_is_idle(ref));
 	/*
 	 * Try to reuse any existing barrier nodes already allocated for this
 	 * i915_active, due to overlapping active phases there is likely a
 	 * node kept alive (as we reuse before parking). We prefer to reuse
 	 * completely idle barriers (less hassle in manipulating the llists),
 	 * but otherwise any will do.
 	 */
 	if (ref->cache && is_idle_barrier(ref->cache, idx)) {
 		p = &ref->cache->node;
 		goto match;
+	}
 #ifdef __NetBSD__
+    {
 	struct active_node *node =
 	    rb_tree_find_node_leq(&ref->tree.rbr_tree, &idx);
 	if (node) {
 		if (node->timeline == idx && is_idle_barrier(node, idx)) {
 			p = &node->node;
 			goto match;
+		}
 		prev = &node->node;
 	} else {
 		prev = NULL;
+	}
+    }
 #else
 	prev = NULL;
 	p = ref->tree.rb_node;
 	while (p) {
 		struct active_node *node =
 			rb_entry(p, struct active_node, node);
 		if (is_idle_barrier(node, idx))
 			goto match;
 		prev = p;
 		if (node->timeline < idx)
 			p = p->rb_right;
 		else
 			p = p->rb_left;
+	}
 #endif
 	/*
 	 * No quick match, but we did find the leftmost rb_node for the
 	 * kernel_context. Walk the rb_tree in-order to see if there were
 	 * any idle-barriers on this timeline that we missed, or just use
 	 * the first pending barrier.
 	 */
 	for (p = prev; p; p = rb_next2(&ref->tree, p)) {
 		struct active_node *node =
 			rb_entry(p, struct active_node, node);
 		struct intel_engine_cs *engine;
 		if (node->timeline > idx)
 			break;
 		if (node->timeline < idx)
 			continue;
 		if (is_idle_barrier(node, idx))
 			goto match;
 		/*
 		 * The list of pending barriers is protected by the
 		 * kernel_context timeline, which notably we do not hold
 		 * here. i915_request_add_active_barriers() may consume
 		 * the barrier before we claim it, so we have to check
 		 * for success.
 		 */
 		engine = __barrier_to_engine(node);
 		smp_rmb(); /* serialise with add_active_barriers */
 		if (is_barrier(&node->base) &&
 		    ____active_del_barrier(ref, node, engine))
 			goto match;
+	}
 	spin_unlock_irq(&ref->tree_lock);
 	return NULL;
 match:
 	rb_erase(p, &ref->tree); /* Hide from waits and sibling allocations */
 	if (p == &ref->cache->node)
 		ref->cache = NULL;
 	spin_unlock_irq(&ref->tree_lock);
 	return rb_entry(p, struct active_node, node);
+}
 int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
 					    struct intel_engine_cs *engine)
+{
 	intel_engine_mask_t tmp, mask = engine->mask;
 	struct llist_node *first = NULL, *last = NULL;
 	struct intel_gt *gt = engine->gt;
 	int err;
 	GEM_BUG_ON(i915_active_is_idle(ref));
 	/* Wait until the previous preallocation is completed */
 	while (!llist_empty(&ref->preallocated_barriers))
 		cond_resched();
 	/*
 	 * Preallocate a node for each physical engine supporting the target
 	 * engine (remember virtual engines have more than one sibling).
 	 * We can then use the preallocated nodes in
 	 * i915_active_acquire_barrier()
 	 */
 	for_each_engine_masked(engine, gt, mask, tmp) {
 		u64 idx = engine->kernel_context->timeline->fence_context;
 		struct llist_node *prev = first;
 		struct active_node *node;
 		node = reuse_idle_barrier(ref, idx);
 		if (!node) {
 			node = kmem_cache_alloc(global.slab_cache, GFP_KERNEL);
 			if (!node) {
 				err = ENOMEM;
 				goto unwind;
+			}
 			memset(node, 0, sizeof(*node));
 			RCU_INIT_POINTER(node->base.fence, NULL);
 			node->base.cb.func = node_retire;
 			node->timeline = idx;
 			node->ref = ref;
+		}
 		if (!i915_active_fence_isset(&node->base)) {
 			/*
 			 * Mark this as being *our* unconnected proto-node.
+			 *
 			 * Since this node is not in any list, and we have
 			 * decoupled it from the rbtree, we can reuse the
 			 * request to indicate this is an idle-barrier node
 			 * and then we can use the rb_node and list pointers
 			 * for our tracking of the pending barrier.
 			 */
 			RCU_INIT_POINTER(node->base.fence, ERR_PTR(-EAGAIN));
 			node->engine = engine;
 			atomic_inc(&ref->count);
+		}
 		GEM_BUG_ON(rcu_access_pointer(node->base.fence) != ERR_PTR(-EAGAIN));
 		GEM_BUG_ON(barrier_to_engine(node) != engine);
 		first = barrier_to_ll(node);
 		first->next = prev;
 		if (!last)
 			last = first;
 		intel_engine_pm_get(engine);
+	}
 	GEM_BUG_ON(!llist_empty(&ref->preallocated_barriers));
 	llist_add_batch(first, last, &ref->preallocated_barriers);
 	return 0;
 unwind:
 	while (first) {
 		struct active_node *node = barrier_from_ll(first);
 		first = first->next;
 		atomic_dec(&ref->count);
 		intel_engine_pm_put(barrier_to_engine(node));
 		kmem_cache_free(global.slab_cache, node);
+	}
 	return err;
+}
 void i915_active_acquire_barrier(struct i915_active *ref)
+{
 	struct llist_node *pos, *next;
 	unsigned long flags;
 	GEM_BUG_ON(i915_active_is_idle(ref));
 	/*
 	 * Transfer the list of preallocated barriers into the
 	 * i915_active rbtree, but only as proto-nodes. They will be
 	 * populated by i915_request_add_active_barriers() to point to the
 	 * request that will eventually release them.
 	 */
 	llist_for_each_safe(pos, next, take_preallocated_barriers(ref)) {
 		struct active_node *node = barrier_from_ll(pos);
 		struct intel_engine_cs *engine = barrier_to_engine(node);
 		struct rb_node **p, *parent;
 		spin_lock_irqsave_nested(&ref->tree_lock, flags,
 					 SINGLE_DEPTH_NESTING);
 #ifdef __NetBSD__
 		__USE(p);
 		__USE(parent);
 		struct active_node *collision __diagused;
 		collision = rb_tree_insert_node(&ref->tree.rbr_tree, node);
 		KASSERT(collision == node);
 #else
 		parent = NULL;
 		p = &ref->tree.rb_node;
 		while (*p) {
 			struct active_node *it;
 			parent = *p;
 			it = rb_entry(parent, struct active_node, node);
 			if (it->timeline < node->timeline)
 				p = &parent->rb_right;
 			else
 				p = &parent->rb_left;
+		}
 		rb_link_node(&node->node, parent, p);
 		rb_insert_color(&node->node, &ref->tree);
 #endif
 		spin_unlock_irqrestore(&ref->tree_lock, flags);
 		GEM_BUG_ON(!intel_engine_pm_is_awake(engine));
 		llist_add(barrier_to_ll(node), &engine->barrier_tasks);
 		intel_engine_pm_put(engine);
+	}
+}
 static struct dma_fence **ll_to_fence_slot(struct llist_node *node)
+{
 	return __active_fence_slot(&barrier_from_ll(node)->base);
+}
 void i915_request_add_active_barriers(struct i915_request *rq)
+{
 	struct intel_engine_cs *engine = rq->engine;
 	struct llist_node *node, *next;
 	unsigned long flags;
 	GEM_BUG_ON(!intel_context_is_barrier(rq->context));
 	GEM_BUG_ON(intel_engine_is_virtual(engine));
 	GEM_BUG_ON(i915_request_timeline(rq) != engine->kernel_context->timeline);
 	node = llist_del_all(&engine->barrier_tasks);
 	if (!node)
 		return;
 	/*
 	 * Attach the list of proto-fences to the in-flight request such
 	 * that the parent i915_active will be released when this request
 	 * is retired.
 	 */
 	spin_lock_irqsave(&rq->lock, flags);
 	llist_for_each_safe(node, next, node) {
 		/* serialise with reuse_idle_barrier */
 		smp_store_mb(*ll_to_fence_slot(node), &rq->fence);
 #ifdef __NetBSD__
 		/* XXX ugh bletch */
 		struct i915_active_fence *active =
 		    container_of(node, struct i915_active_fence, llist);
 		/* XXX something bad went wrong in making this code */
 		KASSERT(active->cb.func == node_retire ||
 		    active->cb.func == excl_retire ||
 		    active->cb.func == i915_active_noop);
 		KASSERTMSG(active->fence == &rq->fence,
 		    "active=%p fence=%p; rq=%p fence=%p",
 		    active, active->fence, rq, &rq->fence);
 		KASSERTMSG(!active->cb.fcb_onqueue, "active=%p", active);
 		active->cb.fcb_onqueue = true;
 		TAILQ_INSERT_TAIL(&rq->fence.f_callbacks, &active->cb,
 		    fcb_entry);
 #else
 		list_add_tail((struct list_head *)node, &rq->fence.cb_list);
 #endif
+	}
 	spin_unlock_irqrestore(&rq->lock, flags);
+}
 /*
  * __i915_active_fence_set: Update the last active fence along its timeline
  * @active: the active tracker
  * @fence: the new fence (under construction)
+ *
  * Records the new @fence as the last active fence along its timeline in
  * this active tracker, moving the tracking callbacks from the previous
  * fence onto this one. Returns the previous fence (if not already completed),
  * which the caller must ensure is executed before the new fence. To ensure
  * that the order of fences within the timeline of the i915_active_fence is
  * understood, it should be locked by the caller.
  */
 struct dma_fence *
 __i915_active_fence_set(struct i915_active_fence *active,
 			struct dma_fence *fence)
+{
 	struct dma_fence *prev;
 	unsigned long flags;
 	if (fence == rcu_access_pointer(active->fence))
 		return fence;
 	GEM_BUG_ON(test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags));
 	/*
 	 * Consider that we have two threads arriving (A and B), with
 	 * C already resident as the active->fence.
+	 *
 	 * A does the xchg first, and so it sees C or NULL depending
 	 * on the timing of the interrupt handler. If it is NULL, the
 	 * previous fence must have been signaled and we know that
 	 * we are first on the timeline. If it is still present,
 	 * we acquire the lock on that fence and serialise with the interrupt
 	 * handler, in the process removing it from any future interrupt
 	 * callback. A will then wait on C before executing (if present).
+	 *
 	 * As B is second, it sees A as the previous fence and so waits for
 	 * it to complete its transition and takes over the occupancy for
 	 * itself -- remembering that it needs to wait on A before executing.
+	 *
 	 * Note the strong ordering of the timeline also provides consistent
 	 * nesting rules for the fence->lock; the inner lock is always the
 	 * older lock.
 	 */
 	spin_lock_irqsave(fence->lock, flags);
 	prev = xchg(__active_fence_slot(active), fence);
 	if (prev) {
 		GEM_BUG_ON(prev == fence);
 		spin_lock_nested(prev->lock, SINGLE_DEPTH_NESTING);
 #ifdef __NetBSD__
 		/* XXX ugh bletch */
 		KASSERT(active->cb.func == node_retire ||
 		    active->cb.func == excl_retire ||
 		    active->cb.func == i915_active_noop);
 		if (active->cb.fcb_onqueue) {
 			TAILQ_REMOVE(&prev->f_callbacks, &active->cb,
 			    fcb_entry);
 			active->cb.fcb_onqueue = false;
+		}
 #else
 		__list_del_entry(&active->cb.node);
 #endif
 		spin_unlock(prev->lock); /* serialise with prev->cb_list */
+	}
 	GEM_BUG_ON(rcu_access_pointer(active->fence) != fence);
 #ifdef __NetBSD__
 	/* XXX ugh bletch */
 	KASSERT(!active->cb.fcb_onqueue);
 	active->cb.fcb_onqueue = true;
 	TAILQ_INSERT_TAIL(&fence->f_callbacks, &active->cb, fcb_entry);
 #else
 	list_add_tail(&active->cb.node, &fence->cb_list);
 #endif
 	spin_unlock_irqrestore(fence->lock, flags);
 	return prev;
+}
 int i915_active_fence_set(struct i915_active_fence *active,
 			  struct i915_request *rq)
+{
 	struct dma_fence *fence;
 	int err = 0;
 	/* Must maintain timeline ordering wrt previous active requests */
 	rcu_read_lock();
 	fence = __i915_active_fence_set(active, &rq->fence);
 	if (fence) /* but the previous fence may not belong to that timeline! */
 		fence = dma_fence_get_rcu(fence);
 	rcu_read_unlock();
 	if (fence) {
 		err = i915_request_await_dma_fence(rq, fence);
 		dma_fence_put(fence);
+	}
 	return err;
+}
 void i915_active_noop(struct dma_fence *fence, struct dma_fence_cb *cb)
+{
 	active_fence_cb(fence, cb);
+}
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/i915_active.c"
 #endif
 static void i915_global_active_shrink(void)
+{
 	kmem_cache_shrink(global.slab_cache);
+}
 static void i915_global_active_exit(void)
+{
 	kmem_cache_destroy(global.slab_cache);
+}
 static struct i915_global_active global = { {
 	.shrink = i915_global_active_shrink,
 	.exit = i915_global_active_exit,
 } };
 int __init i915_global_active_init(void)
+{
 	global.slab_cache = KMEM_CACHE(active_node, SLAB_HWCACHE_ALIGN);
 	if (!global.slab_cache)
 		return -ENOMEM;
 	i915_global_register(&global.base);
 	return 0;
+}