rxrpc: Offload the completion of service conn security to the I/O thread

Offload the completion of the challenge/response cycle on a service
connection to the I/O thread.  After the RESPONSE packet has been
successfully decrypted and verified by the work queue, offloading the
changing of the call states to the I/O thread makes iteration over the
conn's channel list simpler.

Do this by marking the RESPONSE skbuff and putting it onto the receive
queue for the I/O thread to collect.  We put it on the front of the queue
as we've already received the packet for it.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

include/trace/events/rxrpc.h

@@ -126,6 +126,7 @@
 #define rxrpc_skb_traces \
 	EM(rxrpc_skb_eaten_by_unshare,		"ETN unshare  ") \
 	EM(rxrpc_skb_eaten_by_unshare_nomem,	"ETN unshar-nm") \
+	EM(rxrpc_skb_get_conn_secured,		"GET conn-secd") \
 	EM(rxrpc_skb_get_conn_work,		"GET conn-work") \
 	EM(rxrpc_skb_get_local_work,		"GET locl-work") \
 	EM(rxrpc_skb_get_reject_work,		"GET rej-work ") \
@@ -135,6 +136,7 @@
 	EM(rxrpc_skb_new_error_report,		"NEW error-rpt") \
 	EM(rxrpc_skb_new_jumbo_subpacket,	"NEW jumbo-sub") \
 	EM(rxrpc_skb_new_unshared,		"NEW unshared ") \
+	EM(rxrpc_skb_put_conn_secured,		"PUT conn-secd") \
 	EM(rxrpc_skb_put_conn_work,		"PUT conn-work") \
 	EM(rxrpc_skb_put_error_report,		"PUT error-rep") \
 	EM(rxrpc_skb_put_input,			"PUT input    ") \

net/rxrpc/ar-internal.h

@@ -38,6 +38,7 @@ struct rxrpc_txbuf;
 enum rxrpc_skb_mark {
 	RXRPC_SKB_MARK_PACKET,		/* Received packet */
 	RXRPC_SKB_MARK_ERROR,		/* Error notification */
+	RXRPC_SKB_MARK_SERVICE_CONN_SECURED, /* Service connection response has been verified */
 	RXRPC_SKB_MARK_REJECT_BUSY,	/* Reject with BUSY */
 	RXRPC_SKB_MARK_REJECT_ABORT,	/* Reject with ABORT (code in skb->priority) */
 };

net/rxrpc/conn_event.c

@@ -248,7 +248,7 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
 			       struct sk_buff *skb)
 {
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
-	int loop, ret;
+	int ret;
 
 	if (conn->state == RXRPC_CONN_ABORTED)
 		return -ECONNABORTED;
@@ -269,22 +269,21 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
 		if (ret < 0)
 			return ret;
 
-		spin_lock(&conn->bundle->channel_lock);
 		spin_lock(&conn->state_lock);
-
-		if (conn->state == RXRPC_CONN_SERVICE_CHALLENGING) {
+		if (conn->state == RXRPC_CONN_SERVICE_CHALLENGING)
 			conn->state = RXRPC_CONN_SERVICE;
-			spin_unlock(&conn->state_lock);
-			for (loop = 0; loop < RXRPC_MAXCALLS; loop++)
-				rxrpc_call_is_secure(
-					rcu_dereference_protected(
-						conn->channels[loop].call,
-						lockdep_is_held(&conn->bundle->channel_lock)));
-		} else {
-			spin_unlock(&conn->state_lock);
-		}
+		spin_unlock(&conn->state_lock);
 
-		spin_unlock(&conn->bundle->channel_lock);
+		if (conn->state == RXRPC_CONN_SERVICE) {
+			/* Offload call state flipping to the I/O thread.  As
+			 * we've already received the packet, put it on the
+			 * front of the queue.
+			 */
+			skb->mark = RXRPC_SKB_MARK_SERVICE_CONN_SECURED;
+			rxrpc_get_skb(skb, rxrpc_skb_get_conn_secured);
+			skb_queue_head(&conn->local->rx_queue, skb);
+			rxrpc_wake_up_io_thread(conn->local);
+		}
 		return 0;
 
 	default:
@@ -442,9 +441,28 @@ bool rxrpc_input_conn_packet(struct rxrpc_connection *conn, struct sk_buff *skb)
  */
 void rxrpc_input_conn_event(struct rxrpc_connection *conn, struct sk_buff *skb)
 {
+	unsigned int loop;
+
 	if (test_and_clear_bit(RXRPC_CONN_EV_ABORT_CALLS, &conn->events))
 		rxrpc_abort_calls(conn);
 
+	switch (skb->mark) {
+	case RXRPC_SKB_MARK_SERVICE_CONN_SECURED:
+		if (conn->state != RXRPC_CONN_SERVICE)
+			break;
+
+		spin_lock(&conn->bundle->channel_lock);
+
+		for (loop = 0; loop < RXRPC_MAXCALLS; loop++)
+			rxrpc_call_is_secure(
+				rcu_dereference_protected(
+					conn->channels[loop].call,
+					lockdep_is_held(&conn->bundle->channel_lock)));
+
+		spin_unlock(&conn->bundle->channel_lock);
+		break;
+	}
+
 	/* Process delayed ACKs whose time has come. */
 	if (conn->flags & RXRPC_CONN_FINAL_ACK_MASK)
 		rxrpc_process_delayed_final_acks(conn, false);

net/rxrpc/io_thread.c

@@ -451,6 +451,7 @@ int rxrpc_io_thread(void *data)
 
 		/* Process received packets and errors. */
 		if ((skb = __skb_dequeue(&rx_queue))) {
+			struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 			switch (skb->mark) {
 			case RXRPC_SKB_MARK_PACKET:
 				skb->priority = 0;
@@ -463,6 +464,10 @@ int rxrpc_io_thread(void *data)
 				rxrpc_input_error(local, skb);
 				rxrpc_free_skb(skb, rxrpc_skb_put_error_report);
 				break;
+			case RXRPC_SKB_MARK_SERVICE_CONN_SECURED:
+				rxrpc_input_conn_event(sp->conn, skb);
+				rxrpc_put_connection(sp->conn, rxrpc_conn_put_poke);
+				rxrpc_free_skb(skb, rxrpc_skb_put_conn_secured);
 				break;
 			default:
 				WARN_ON_ONCE(1);