[PATCH v3 04/11] net: qrtr: support identical node ids

[Mihai Moldovan <ionic@ionic.de>]

From: Denis Kenzior <denkenz@gmail.com>

Add support for tracking multiple endpoints that may have conflicting
node identifiers. This is achieved by using both the node and endpoint
identifiers as the key inside the radix_tree data structure.

For backward compatibility with existing clients, the previous key
schema (node identifier only) is preserved. However, this schema will
only support the first endpoint/node combination.  This is acceptable
for legacy clients as support for multiple endpoints with conflicting
node identifiers was not previously possible.

Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Andy Gross <agross@kernel.org>
Signed-off-by: Mihai Moldovan <ionic@ionic.de>

---

v3:
  - rebase against current master
  - port usage of [endpoint ID|node ID] key usage to the generic
    solution already established for the [node ID|port number] usage
  - Link to v2: https://msgid.link/4d0fe1eab4b38fb85e2ec53c07289bc0843611a2.1752947108.git.ionic@ionic.de

v2:
  - rebase against current master
  - no action on review comment regarding integer overflow on 32 bit
    long platforms (thus far)
  - Link to v1: https://msgid.link/20241018181842.1368394-4-denkenz@gmail.com
---
 net/qrtr/af_qrtr.c | 50 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 37 insertions(+), 13 deletions(-)

diff --git a/net/qrtr/af_qrtr.c b/net/qrtr/af_qrtr.c
index 1cb13242e41b..d6efd7f2eddf 100644
--- a/net/qrtr/af_qrtr.c
+++ b/net/qrtr/af_qrtr.c
@@ -119,14 +119,15 @@ static DEFINE_XARRAY_ALLOC(qrtr_ports);
 
 /* The radix tree API uses fixed unsigned long keys and we will have to make
  * do with that.
- * These keys are often a combination of node IDs (currently u32) and
- * port numbers (also currently u32).
- * Using the high 32 bits for the node ID and the low 32 bits for the
- * port number will work fine to create keys on platforms where unsigned long
- * is 64 bits wide, but obviously is not be possible on platforms where
- * unsigned long is smaller.
+ * These keys are often a combination of node IDs and port numbers or
+ * endpoint IDs and node IDs (all currently u32).
+ * Using the high 32 bits for the node/endpoint ID and the low 32 bits for the
+ * port number/node ID will work fine to create keys on platforms where
+ * unsigned long is 64 bits wide, but obviously is not be possible on
+ * platforms where unsigned long is smaller.
  * Virtually split up unsigned long in half and assign the upper bits to
- * node IDs and the lower bits to the port number, however big that may be.
+ * node/endpoint IDs and the lower bits to the port number/node ID, however
+ * big that may be.
  */
 #define QRTR_INDEX_HALF_BITS (RADIX_TREE_INDEX_BITS >> 1)
 
@@ -465,19 +466,36 @@ static struct qrtr_node *qrtr_node_lookup(unsigned int nid)
  *
  * This is mostly useful for automatic node id assignment, based on
  * the source id in the incoming packet.
+ *
+ * Return: 0 on success; negative error code on failure
  */
-static void qrtr_node_assign(struct qrtr_node *node, unsigned int nid)
+static int qrtr_node_assign(struct qrtr_node *node, unsigned int nid)
 {
 	unsigned long flags;
+	unsigned long key;
 
 	if (nid == QRTR_EP_NID_AUTO)
-		return;
+		return 0;
 
 	spin_lock_irqsave(&qrtr_nodes_lock, flags);
-	radix_tree_insert(&qrtr_nodes, nid, node);
+
+	if (node->ep->id > QRTR_INDEX_HALF_UNSIGNED_MAX ||
+	    nid > QRTR_INDEX_HALF_UNSIGNED_MAX)
+		return -EINVAL;
+
+	/* Always insert with the endpoint_id + node_id */
+	key = ((unsigned long)(node->ep->id) << QRTR_INDEX_HALF_BITS) |
+	      ((unsigned long)(nid) & QRTR_INDEX_HALF_UNSIGNED_MAX);
+	radix_tree_insert(&qrtr_nodes, key, node);
+
+	if (!radix_tree_lookup(&qrtr_nodes, nid))
+		radix_tree_insert(&qrtr_nodes, nid, node);
+
 	if (node->nid == QRTR_EP_NID_AUTO)
 		node->nid = nid;
 	spin_unlock_irqrestore(&qrtr_nodes_lock, flags);
+
+	return 0;
 }
 
 /**
@@ -571,14 +589,18 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
 
 	skb_put_data(skb, data + hdrlen, size);
 
-	qrtr_node_assign(node, cb->src_node);
+	ret = qrtr_node_assign(node, cb->src_node);
+	if (ret)
+		goto err;
 
 	if (cb->type == QRTR_TYPE_NEW_SERVER) {
 		/* Remote node endpoint can bridge other distant nodes */
 		const struct qrtr_ctrl_pkt *pkt;
 
 		pkt = data + hdrlen;
-		qrtr_node_assign(node, le32_to_cpu(pkt->server.node));
+		ret = qrtr_node_assign(node, le32_to_cpu(pkt->server.node));
+		if (ret)
+			goto err;
 	}
 
 	if (cb->type == QRTR_TYPE_RESUME_TX) {
@@ -670,7 +692,9 @@ int qrtr_endpoint_register(struct qrtr_endpoint *ep, unsigned int nid)
 	INIT_RADIX_TREE(&node->qrtr_tx_flow, GFP_KERNEL);
 	mutex_init(&node->qrtr_tx_lock);
 
-	qrtr_node_assign(node, nid);
+	rc = qrtr_node_assign(node, nid);
+	if (rc < 0)
+		goto free_node;
 
 	mutex_lock(&qrtr_node_lock);
 	list_add(&node->item, &qrtr_all_nodes);
-- 
2.50.0