[PATCH 7/7] iommu/arm-smmu-v3: Use the new rb tree helpers

[Jason Gunthorpe]

Since v5.12 the rbtree has gained some simplifying helpers aimed at making
rb tree users write less convoluted boiler plate code. Instead the caller
provides a single comparison function and the helpers generate the prior
open-coded stuff.

Update smmu->streams to use rb_find_add() and rb_find().

Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 68 ++++++++++-----------
 1 file changed, 31 insertions(+), 37 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 7a6c9aac4cd450..25bae0b05a488c 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1667,26 +1667,37 @@ static int arm_smmu_init_l2_strtab(struct arm_smmu_device *smmu, u32 sid)
 	return 0;
 }
 
+static int arm_smmu_streams_cmp_key(const void *lhs, const struct rb_node *rhs)
+{
+	struct arm_smmu_stream *stream_rhs =
+		rb_entry(rhs, struct arm_smmu_stream, node);
+	const u32 *sid_lhs = lhs;
+
+	if (*sid_lhs < stream_rhs->id)
+		return -1;
+	if (*sid_lhs > stream_rhs->id)
+		return 1;
+	return 0;
+}
+
+static int arm_smmu_streams_cmp_node(struct rb_node *lhs,
+				     const struct rb_node *rhs)
+{
+	return arm_smmu_streams_cmp_key(
+		&rb_entry(lhs, struct arm_smmu_stream, node)->id, rhs);
+}
+
 static struct arm_smmu_master *
 arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
 {
 	struct rb_node *node;
-	struct arm_smmu_stream *stream;
 
 	lockdep_assert_held(&smmu->streams_mutex);
 
-	node = smmu->streams.rb_node;
-	while (node) {
-		stream = rb_entry(node, struct arm_smmu_stream, node);
-		if (stream->id < sid)
-			node = node->rb_right;
-		else if (stream->id > sid)
-			node = node->rb_left;
-		else
-			return stream->master;
-	}
-
-	return NULL;
+	node = rb_find(&sid, &smmu->streams, arm_smmu_streams_cmp_key);
+	if (!node)
+		return NULL;
+	return rb_entry(node, struct arm_smmu_stream, node)->master;
 }
 
 /* IRQ and event handlers */
@@ -2795,8 +2806,6 @@ static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
 {
 	int i;
 	int ret = 0;
-	struct arm_smmu_stream *new_stream, *cur_stream;
-	struct rb_node **new_node, *parent_node = NULL;
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev);
 
 	master->streams = kcalloc(fwspec->num_ids, sizeof(*master->streams),
@@ -2807,9 +2816,9 @@ static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
 
 	mutex_lock(&smmu->streams_mutex);
 	for (i = 0; i < fwspec->num_ids; i++) {
+		struct arm_smmu_stream *new_stream = &master->streams[i];
 		u32 sid = fwspec->ids[i];
 
-		new_stream = &master->streams[i];
 		new_stream->id = sid;
 		new_stream->master = master;
 
@@ -2818,28 +2827,13 @@ static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
 			break;
 
 		/* Insert into SID tree */
-		new_node = &(smmu->streams.rb_node);
-		while (*new_node) {
-			cur_stream = rb_entry(*new_node, struct arm_smmu_stream,
-					      node);
-			parent_node = *new_node;
-			if (cur_stream->id > new_stream->id) {
-				new_node = &((*new_node)->rb_left);
-			} else if (cur_stream->id < new_stream->id) {
-				new_node = &((*new_node)->rb_right);
-			} else {
-				dev_warn(master->dev,
-					 "stream %u already in tree\n",
-					 cur_stream->id);
-				ret = -EINVAL;
-				break;
-			}
-		}
-		if (ret)
+		if (rb_find_add(&new_stream->node, &smmu->streams,
+				arm_smmu_streams_cmp_node)) {
+			dev_warn(master->dev, "stream %u already in tree\n",
+				 sid);
+			ret = -EINVAL;
 			break;
-
-		rb_link_node(&new_stream->node, parent_node, new_node);
-		rb_insert_color(&new_stream->node, &smmu->streams);
+		}
 	}
 
 	if (ret) {
-- 
2.45.2