net: qrtr: Migrate node lookup tree to spinlock

Move operations on the qrtr_nodes radix tree under a separate spinlock
and make the qrtr_nodes tree GFP_ATOMIC, to allow operation from atomic
context in a subsequent patch.
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/qrtr/qrtr.c

@@ -8,6 +8,7 @@
 #include <linux/qrtr.h>
 #include <linux/termios.h>	/* For TIOCINQ/OUTQ */
 #include <linux/numa.h>
+#include <linux/spinlock.h>
 #include <linux/wait.h>
 
 #include <net/sock.h>
@@ -98,10 +99,11 @@ static inline struct qrtr_sock *qrtr_sk(struct sock *sk)
 static unsigned int qrtr_local_nid = NUMA_NO_NODE;
 
 /* for node ids */
-static RADIX_TREE(qrtr_nodes, GFP_KERNEL);
+static RADIX_TREE(qrtr_nodes, GFP_ATOMIC);
+static DEFINE_SPINLOCK(qrtr_nodes_lock);
 /* broadcast list */
 static LIST_HEAD(qrtr_all_nodes);
-/* lock for qrtr_nodes, qrtr_all_nodes and node reference */
+/* lock for qrtr_all_nodes and node reference */
 static DEFINE_MUTEX(qrtr_node_lock);
 
 /* local port allocation management */
@@ -165,10 +167,13 @@ static void __qrtr_node_release(struct kref *kref)
 {
 	struct qrtr_node *node = container_of(kref, struct qrtr_node, ref);
 	struct radix_tree_iter iter;
+	unsigned long flags;
 	void __rcu **slot;
 
+	spin_lock_irqsave(&qrtr_nodes_lock, flags);
 	if (node->nid != QRTR_EP_NID_AUTO)
 		radix_tree_delete(&qrtr_nodes, node->nid);
+	spin_unlock_irqrestore(&qrtr_nodes_lock, flags);
 
 	list_del(&node->item);
 	mutex_unlock(&qrtr_node_lock);
@@ -376,11 +381,12 @@ static int qrtr_node_enqueue(struct qrtr_node *node, struct sk_buff *skb,
 static struct qrtr_node *qrtr_node_lookup(unsigned int nid)
 {
 	struct qrtr_node *node;
+	unsigned long flags;
 
-	mutex_lock(&qrtr_node_lock);
+	spin_lock_irqsave(&qrtr_nodes_lock, flags);
 	node = radix_tree_lookup(&qrtr_nodes, nid);
 	node = qrtr_node_acquire(node);
-	mutex_unlock(&qrtr_node_lock);
+	spin_unlock_irqrestore(&qrtr_nodes_lock, flags);
 
 	return node;
 }
@@ -392,13 +398,15 @@ static struct qrtr_node *qrtr_node_lookup(unsigned int nid)
  */
 static void qrtr_node_assign(struct qrtr_node *node, unsigned int nid)
 {
+	unsigned long flags;
+
 	if (node->nid != QRTR_EP_NID_AUTO || nid == QRTR_EP_NID_AUTO)
 		return;
 
-	mutex_lock(&qrtr_node_lock);
+	spin_lock_irqsave(&qrtr_nodes_lock, flags);
 	radix_tree_insert(&qrtr_nodes, nid, node);
 	node->nid = nid;
-	mutex_unlock(&qrtr_node_lock);
+	spin_unlock_irqrestore(&qrtr_nodes_lock, flags);
 }
 
 /**