qrtr: Convert qrtr_ports from IDR to XArray

The XArray interface is easier for this driver to use.  Also fixes a
bug reported by the improper use of GFP_ATOMIC.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/qrtr/qrtr.c

@@ -20,6 +20,8 @@
 /* auto-bind range */
 #define QRTR_MIN_EPH_SOCKET 0x4000
 #define QRTR_MAX_EPH_SOCKET 0x7fff
+#define QRTR_EPH_PORT_RANGE \
+		XA_LIMIT(QRTR_MIN_EPH_SOCKET, QRTR_MAX_EPH_SOCKET)
 
 /**
  * struct qrtr_hdr_v1 - (I|R)PCrouter packet header version 1
@@ -106,8 +108,7 @@ static LIST_HEAD(qrtr_all_nodes);
 static DEFINE_MUTEX(qrtr_node_lock);
 
 /* local port allocation management */
-static DEFINE_IDR(qrtr_ports);
-static DEFINE_MUTEX(qrtr_port_lock);
+static DEFINE_XARRAY_ALLOC(qrtr_ports);
 
 /**
  * struct qrtr_node - endpoint node
@@ -653,7 +654,7 @@ static struct qrtr_sock *qrtr_port_lookup(int port)
 		port = 0;
 
 	rcu_read_lock();
-	ipc = idr_find(&qrtr_ports, port);
+	ipc = xa_load(&qrtr_ports, port);
 	if (ipc)
 		sock_hold(&ipc->sk);
 	rcu_read_unlock();
@@ -695,9 +696,7 @@ static void qrtr_port_remove(struct qrtr_sock *ipc)
 
 	__sock_put(&ipc->sk);
 
-	mutex_lock(&qrtr_port_lock);
-	idr_remove(&qrtr_ports, port);
-	mutex_unlock(&qrtr_port_lock);
+	xa_erase(&qrtr_ports, port);
 
 	/* Ensure that if qrtr_port_lookup() did enter the RCU read section we
 	 * wait for it to up increment the refcount */
@@ -716,29 +715,20 @@ static void qrtr_port_remove(struct qrtr_sock *ipc)
  */
 static int qrtr_port_assign(struct qrtr_sock *ipc, int *port)
 {
-	u32 min_port;
 	int rc;
 
-	mutex_lock(&qrtr_port_lock);
 	if (!*port) {
-		min_port = QRTR_MIN_EPH_SOCKET;
-		rc = idr_alloc_u32(&qrtr_ports, ipc, &min_port, QRTR_MAX_EPH_SOCKET, GFP_ATOMIC);
-		if (!rc)
-			*port = min_port;
+		rc = xa_alloc(&qrtr_ports, port, ipc, QRTR_EPH_PORT_RANGE,
+				GFP_KERNEL);
 	} else if (*port < QRTR_MIN_EPH_SOCKET && !capable(CAP_NET_ADMIN)) {
 		rc = -EACCES;
 	} else if (*port == QRTR_PORT_CTRL) {
-		min_port = 0;
-		rc = idr_alloc_u32(&qrtr_ports, ipc, &min_port, 0, GFP_ATOMIC);
+		rc = xa_insert(&qrtr_ports, 0, ipc, GFP_KERNEL);
 	} else {
-		min_port = *port;
-		rc = idr_alloc_u32(&qrtr_ports, ipc, &min_port, *port, GFP_ATOMIC);
-		if (!rc)
-			*port = min_port;
+		rc = xa_insert(&qrtr_ports, *port, ipc, GFP_KERNEL);
 	}
-	mutex_unlock(&qrtr_port_lock);
 
-	if (rc == -ENOSPC)
+	if (rc == -EBUSY)
 		return -EADDRINUSE;
 	else if (rc < 0)
 		return rc;
@@ -752,20 +742,16 @@ static int qrtr_port_assign(struct qrtr_sock *ipc, int *port)
 static void qrtr_reset_ports(void)
 {
 	struct qrtr_sock *ipc;
-	int id;
-
-	mutex_lock(&qrtr_port_lock);
-	idr_for_each_entry(&qrtr_ports, ipc, id) {
-		/* Don't reset control port */
-		if (id == 0)
-			continue;
+	unsigned long index;
 
+	rcu_read_lock();
+	xa_for_each_start(&qrtr_ports, index, ipc, 1) {
 		sock_hold(&ipc->sk);
 		ipc->sk.sk_err = ENETRESET;
 		ipc->sk.sk_error_report(&ipc->sk);
 		sock_put(&ipc->sk);
 	}
-	mutex_unlock(&qrtr_port_lock);
+	rcu_read_unlock();
 }
 
 /* Bind socket to address.