1 files changed, 286 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
new file mode 100644
index 000000000000..215b6ff8aa73
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_active.c
@@ -0,0 +1,286 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2019 Intel Corporation
+ */
+
+#include "i915_drv.h"
+#include "i915_active.h"
+
+#define BKL(ref) (&(ref)->i915->drm.struct_mutex)
+
+/*
+ * 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 kmem_cache *slab_cache;
+} global;
+
+struct active_node {
+	struct i915_active_request base;
+	struct i915_active *ref;
+	struct rb_node node;
+	u64 timeline;
+};
+
+static void
+__active_park(struct i915_active *ref)
+{
+	struct active_node *it, *n;
+
+	rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
+		GEM_BUG_ON(i915_active_request_isset(&it->base));
+		kmem_cache_free(global.slab_cache, it);
+	}
+	ref->tree = RB_ROOT;
+}
+
+static void
+__active_retire(struct i915_active *ref)
+{
+	GEM_BUG_ON(!ref->count);
+	if (--ref->count)
+		return;
+
+	/* return the unused nodes to our slabcache */
+	__active_park(ref);
+
+	ref->retire(ref);
+}
+
+static void
+node_retire(struct i915_active_request *base, struct i915_request *rq)
+{
+	__active_retire(container_of(base, struct active_node, base)->ref);
+}
+
+static void
+last_retire(struct i915_active_request *base, struct i915_request *rq)
+{
+	__active_retire(container_of(base, struct i915_active, last));
+}
+
+static struct i915_active_request *
+active_instance(struct i915_active *ref, u64 idx)
+{
+	struct active_node *node;
+	struct rb_node **p, *parent;
+	struct i915_request *old;
+
+	/*
+	 * 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.
+	 *
+	 * Note that we allow the timeline to be active simultaneously in
+	 * the rbtree and the last cache. We do this to avoid having
+	 * to search and replace the rbtree element for a new timeline, with
+	 * the cost being that we must be aware that the ref may be retired
+	 * twice for the same timeline (as the older rbtree element will be
+	 * retired before the new request added to last).
+	 */
+	old = i915_active_request_raw(&ref->last, BKL(ref));
+	if (!old || old->fence.context == idx)
+		goto out;
+
+	/* Move the currently active fence into the rbtree */
+	idx = old->fence.context;
+
+	parent = NULL;
+	p = &ref->tree.rb_node;
+	while (*p) {
+		parent = *p;
+
+		node = rb_entry(parent, struct active_node, node);
+		if (node->timeline == idx)
+			goto replace;
+
+		if (node->timeline < idx)
+			p = &parent->rb_right;
+		else
+			p = &parent->rb_left;
+	}
+
+	node = kmem_cache_alloc(global.slab_cache, GFP_KERNEL);
+
+	/* kmalloc may retire the ref->last (thanks shrinker)! */
+	if (unlikely(!i915_active_request_raw(&ref->last, BKL(ref)))) {
+		kmem_cache_free(global.slab_cache, node);
+		goto out;
+	}
+
+	if (unlikely(!node))
+		return ERR_PTR(-ENOMEM);
+
+	i915_active_request_init(&node->base, NULL, node_retire);
+	node->ref = ref;
+	node->timeline = idx;
+
+	rb_link_node(&node->node, parent, p);
+	rb_insert_color(&node->node, &ref->tree);
+
+replace:
+	/*
+	 * Overwrite the previous active slot in the rbtree with last,
+	 * leaving last zeroed. If the previous slot is still active,
+	 * we must be careful as we now only expect to receive one retire
+	 * callback not two, and so much undo the active counting for the
+	 * overwritten slot.
+	 */
+	if (i915_active_request_isset(&node->base)) {
+		/* Retire ourselves from the old rq->active_list */
+		__list_del_entry(&node->base.link);
+		ref->count--;
+		GEM_BUG_ON(!ref->count);
+	}
+	GEM_BUG_ON(list_empty(&ref->last.link));
+	list_replace_init(&ref->last.link, &node->base.link);
+	node->base.request = fetch_and_zero(&ref->last.request);
+
+out:
+	return &ref->last;
+}
+
+void i915_active_init(struct drm_i915_private *i915,
+		      struct i915_active *ref,
+		      void (*retire)(struct i915_active *ref))
+{
+	ref->i915 = i915;
+	ref->retire = retire;
+	ref->tree = RB_ROOT;
+	i915_active_request_init(&ref->last, NULL, last_retire);
+	ref->count = 0;
+}
+
+int i915_active_ref(struct i915_active *ref,
+		    u64 timeline,
+		    struct i915_request *rq)
+{
+	struct i915_active_request *active;
+
+	active = active_instance(ref, timeline);
+	if (IS_ERR(active))
+		return PTR_ERR(active);
+
+	if (!i915_active_request_isset(active))
+		ref->count++;
+	__i915_active_request_set(active, rq);
+
+	GEM_BUG_ON(!ref->count);
+	return 0;
+}
+
+bool i915_active_acquire(struct i915_active *ref)
+{
+	lockdep_assert_held(BKL(ref));
+	return !ref->count++;
+}
+
+void i915_active_release(struct i915_active *ref)
+{
+	lockdep_assert_held(BKL(ref));
+	__active_retire(ref);
+}
+
+int i915_active_wait(struct i915_active *ref)
+{
+	struct active_node *it, *n;
+	int ret = 0;
+
+	if (i915_active_acquire(ref))
+		goto out_release;
+
+	ret = i915_active_request_retire(&ref->last, BKL(ref));
+	if (ret)
+		goto out_release;
+
+	rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
+		ret = i915_active_request_retire(&it->base, BKL(ref));
+		if (ret)
+			break;
+	}
+
+out_release:
+	i915_active_release(ref);
+	return ret;
+}
+
+int i915_request_await_active_request(struct i915_request *rq,
+				      struct i915_active_request *active)
+{
+	struct i915_request *barrier =
+		i915_active_request_raw(active, &rq->i915->drm.struct_mutex);
+
+	return barrier ? i915_request_await_dma_fence(rq, &barrier->fence) : 0;
+}
+
+int i915_request_await_active(struct i915_request *rq, struct i915_active *ref)
+{
+	struct active_node *it, *n;
+	int ret;
+
+	ret = i915_request_await_active_request(rq, &ref->last);
+	if (ret)
+		return ret;
+
+	rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
+		ret = i915_request_await_active_request(rq, &it->base);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
+void i915_active_fini(struct i915_active *ref)
+{
+	GEM_BUG_ON(i915_active_request_isset(&ref->last));
+	GEM_BUG_ON(!RB_EMPTY_ROOT(&ref->tree));
+	GEM_BUG_ON(ref->count);
+}
+#endif
+
+int i915_active_request_set(struct i915_active_request *active,
+			    struct i915_request *rq)
+{
+	int err;
+
+	/* Must maintain ordering wrt previous active requests */
+	err = i915_request_await_active_request(rq, active);
+	if (err)
+		return err;
+
+	__i915_active_request_set(active, rq);
+	return 0;
+}
+
+void i915_active_retire_noop(struct i915_active_request *active,
+			     struct i915_request *request)
+{
+	/* Space left intentionally blank */
+}
+
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+#include "selftests/i915_active.c"
+#endif
+
+int __init i915_global_active_init(void)
+{
+	global.slab_cache = KMEM_CACHE(active_node, SLAB_HWCACHE_ALIGN);
+	if (!global.slab_cache)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void __exit i915_global_active_exit(void)
+{
+	kmem_cache_destroy(global.slab_cache);
+}