rxrpc: Unlock new call in rxrpc_new_incoming_call() rather than the caller

[ Upstream commit f33121c ]

Move the unlock and the ping transmission for a new incoming call into
rxrpc_new_incoming_call() rather than doing it in the caller.  This makes
it clearer to see what's going on.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
cc: Ingo Molnar <mingo@redhat.com>
cc: Will Deacon <will@kernel.org>
cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: dhowells

net/rxrpc/call_accept.c

@@ -239,6 +239,22 @@ void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
 	kfree(b);
 }
 
+/*
+ * Ping the other end to fill our RTT cache and to retrieve the rwind
+ * and MTU parameters.
+ */
+static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	ktime_t now = skb->tstamp;
+
+	if (call->peer->rtt_usage < 3 ||
+	    ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
+		rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
+				  true, true,
+				  rxrpc_propose_ack_ping_for_params);
+}
+
 /*
  * Allocate a new incoming call from the prealloc pool, along with a connection
  * and a peer as necessary.
@@ -346,9 +362,7 @@ struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 				  sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
 		skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
 		skb->priority = RX_INVALID_OPERATION;
-		_leave(" = NULL [close]");
-		call = NULL;
-		goto out;
+		goto no_call;
 	}
 
 	/* The peer, connection and call may all have sprung into existence due
@@ -361,9 +375,7 @@ struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 	call = rxrpc_alloc_incoming_call(rx, local, peer, conn, skb);
 	if (!call) {
 		skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
-		_leave(" = NULL [busy]");
-		call = NULL;
-		goto out;
+		goto no_call;
 	}
 
 	trace_rxrpc_receive(call, rxrpc_receive_incoming,
@@ -432,10 +444,18 @@ struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 	 */
 	rxrpc_put_call(call, rxrpc_call_put);
 
-	_leave(" = %p{%d}", call, call->debug_id);
-out:
 	spin_unlock(&rx->incoming_lock);
+
+	rxrpc_send_ping(call, skb);
+	mutex_unlock(&call->user_mutex);
+
+	_leave(" = %p{%d}", call, call->debug_id);
 	return call;
+
+no_call:
+	spin_unlock(&rx->incoming_lock);
+	_leave(" = NULL [%u]", skb->mark);
+	return NULL;
 }
 
 /*

net/rxrpc/input.c

@@ -192,22 +192,6 @@ static void rxrpc_congestion_management(struct rxrpc_call *call,
 	goto out_no_clear_ca;
 }
 
-/*
- * Ping the other end to fill our RTT cache and to retrieve the rwind
- * and MTU parameters.
- */
-static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb)
-{
-	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
-	ktime_t now = skb->tstamp;
-
-	if (call->peer->rtt_usage < 3 ||
-	    ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
-		rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
-				  true, true,
-				  rxrpc_propose_ack_ping_for_params);
-}
-
 /*
  * Apply a hard ACK by advancing the Tx window.
  */
@@ -1396,8 +1380,6 @@ int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
 		call = rxrpc_new_incoming_call(local, rx, skb);
 		if (!call)
 			goto reject_packet;
-		rxrpc_send_ping(call, skb);
-		mutex_unlock(&call->user_mutex);
 	}
 
 	/* Process a call packet; this either discards or passes on the ref