drm/xe: Introduce a range-fence utility

Add generic utility to track range conflicts signaled by a dma-fence.
Tracking implemented via an interval tree. An example use case being
tracking conflicts for pending (un)binds from multiple bind engines. By
being generic ths idea would this could moved to the DRM level and used
in multiple drivers for similar problems.

v2: Make interval tree functions static (CI)
v3: Remove non-static cleanup function (CI)

Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

1 files changed, 156 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_range_fence.c b/drivers/gpu/drm/xe/xe_range_fence.c
new file mode 100644
index 000000000000..d35d9ec58e86
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_range_fence.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#include <linux/dma-fence.h>
+#include <linux/interval_tree_generic.h>
+#include <linux/slab.h>
+
+#include "xe_macros.h"
+#include "xe_range_fence.h"
+
+#define XE_RANGE_TREE_START(_node)	((_node)->start)
+#define XE_RANGE_TREE_LAST(_node)	((_node)->last)
+
+INTERVAL_TREE_DEFINE(struct xe_range_fence, rb, u64, __subtree_last,
+		     XE_RANGE_TREE_START, XE_RANGE_TREE_LAST, static,
+		     xe_range_fence_tree);
+
+static void
+xe_range_fence_signal_notify(struct dma_fence *fence, struct dma_fence_cb *cb)
+{
+	struct xe_range_fence *rfence = container_of(cb, typeof(*rfence), cb);
+	struct xe_range_fence_tree *tree = rfence->tree;
+
+	llist_add(&rfence->link, &tree->list);
+}
+
+static bool __xe_range_fence_tree_cleanup(struct xe_range_fence_tree *tree)
+{
+	struct llist_node *node = llist_del_all(&tree->list);
+	struct xe_range_fence *rfence, *next;
+
+	llist_for_each_entry_safe(rfence, next, node, link) {
+		xe_range_fence_tree_remove(rfence, &tree->root);
+		dma_fence_put(rfence->fence);
+		kfree(rfence);
+	}
+
+	return !!node;
+}
+
+/**
+ * xe_range_fence_insert() - range fence insert
+ * @tree: range fence tree to insert intoi
+ * @rfence: range fence
+ * @ops: range fence ops
+ * @start: start address of range fence
+ * @last: last address of range fence
+ * @fence: dma fence which signals range fence can be removed + freed
+ *
+ * Return: 0 on success, non-zero on failure
+ */
+int xe_range_fence_insert(struct xe_range_fence_tree *tree,
+			  struct xe_range_fence *rfence,
+			  const struct xe_range_fence_ops *ops,
+			  u64 start, u64 last, struct dma_fence *fence)
+{
+	int err = 0;
+
+	__xe_range_fence_tree_cleanup(tree);
+
+	if (dma_fence_is_signaled(fence))
+		goto free;
+
+	rfence->ops = ops;
+	rfence->start = start;
+	rfence->last = last;
+	rfence->tree = tree;
+	rfence->fence = dma_fence_get(fence);
+	err = dma_fence_add_callback(fence, &rfence->cb,
+				     xe_range_fence_signal_notify);
+	if (err == -ENOENT) {
+		dma_fence_put(fence);
+		err = 0;
+		goto free;
+	} else if (err == 0) {
+		xe_range_fence_tree_insert(rfence, &tree->root);
+		return 0;
+	}
+
+free:
+	if (ops->free)
+		ops->free(rfence);
+
+	return err;
+}
+
+static void xe_range_fence_tree_remove_all(struct xe_range_fence_tree *tree)
+{
+	struct xe_range_fence *rfence;
+	bool retry = true;
+
+	rfence = xe_range_fence_tree_iter_first(&tree->root, 0, U64_MAX);
+	while (rfence) {
+		/* Should be ok with the minimalistic callback */
+		if (dma_fence_remove_callback(rfence->fence, &rfence->cb))
+			llist_add(&rfence->link, &tree->list);
+		rfence = xe_range_fence_tree_iter_next(rfence, 0, U64_MAX);
+	}
+
+	while (retry)
+		retry = __xe_range_fence_tree_cleanup(tree);
+}
+
+/**
+ * xe_range_fence_tree_init() - Init range fence tree
+ * @tree: range fence tree
+ */
+void xe_range_fence_tree_init(struct xe_range_fence_tree *tree)
+{
+	memset(tree, 0, sizeof(*tree));
+}
+
+/**
+ * xe_range_fence_tree_fini() - Fini range fence tree
+ * @tree: range fence tree
+ */
+void xe_range_fence_tree_fini(struct xe_range_fence_tree *tree)
+{
+	xe_range_fence_tree_remove_all(tree);
+	XE_WARN_ON(!RB_EMPTY_ROOT(&tree->root.rb_root));
+}
+
+/**
+ * xe_range_fence_tree_first() - range fence tree iterator first
+ * @tree: range fence tree
+ * @start: start address of range fence
+ * @last: last address of range fence
+ *
+ * Return: first range fence found in range or NULL
+ */
+struct xe_range_fence *
+xe_range_fence_tree_first(struct xe_range_fence_tree *tree, u64 start,
+			  u64 last)
+{
+	return xe_range_fence_tree_iter_first(&tree->root, start, last);
+}
+
+/**
+ * xe_range_fence_tree_next() - range fence tree iterator next
+ * @rfence: current range fence
+ * @start: start address of range fence
+ * @last: last address of range fence
+ *
+ * Return: next range fence found in range or NULL
+ */
+struct xe_range_fence *
+xe_range_fence_tree_next(struct xe_range_fence *rfence, u64 start, u64 last)
+{
+	return xe_range_fence_tree_iter_next(rfence, start, last);
+}
+
+const struct xe_range_fence_ops xe_range_fence_kfree_ops = {
+	.free = (void (*)(struct xe_range_fence *rfence)) kfree,
+};