rxrpc: Use the peer record to distribute network errors

Use the peer record to distribute network errors rather than the transport
object (which I want to get rid of).  An error from a particular peer
terminates all calls on that peer.

For future consideration:

 (1) For ICMP-induced errors it might be worth trying to extract the RxRPC
     header from the offending packet, if one is returned attached to the
     ICMP packet, to better direct the error.

     This may be overkill, though, since an ICMP packet would be expected
     to be relating to the destination port, machine or network.  RxRPC
     ABORT and BUSY packets give notice at RxRPC level.

 (2) To also abort connection-level communications (such as CHALLENGE
     packets) where indicted by an error - but that requires some revamping
     of the connection event handling first.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 50 insertions, 59 deletions

diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c
index 31c440acd8c9..8940674b5e08 100644
--- a/net/rxrpc/peer_event.c
+++ b/net/rxrpc/peer_event.c
@@ -1,4 +1,4 @@
-/* Error message handling (ICMP)
+/* Peer event handling, typically ICMP messages.
  *
  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
@@ -22,6 +22,8 @@
 #include <net/ip.h>
 #include "ar-internal.h"
 
+static void rxrpc_store_error(struct rxrpc_peer *, struct sock_exterr_skb *);
+
 /*
  * Find the peer associated with an ICMP packet.
  */
@@ -111,12 +113,11 @@ static void rxrpc_adjust_mtu(struct rxrpc_peer *peer, struct sock_exterr_skb *se
 }
 
 /*
- * handle an error received on the local endpoint
+ * Handle an error received on the local endpoint.
  */
 void rxrpc_error_report(struct sock *sk)
 {
 	struct sock_exterr_skb *serr;
-	struct rxrpc_transport *trans;
 	struct rxrpc_local *local = sk->sk_user_data;
 	struct rxrpc_peer *peer;
 	struct sk_buff *skb;
@@ -148,57 +149,37 @@ void rxrpc_error_report(struct sock *sk)
 		return;
 	}
 
-	trans = rxrpc_find_transport(local, peer);
-	if (!trans) {
-		rcu_read_unlock();
-		rxrpc_put_peer(peer);
-		rxrpc_free_skb(skb);
-		_leave(" [no trans]");
-		return;
-	}
-
 	if ((serr->ee.ee_origin == SO_EE_ORIGIN_ICMP &&
 	     serr->ee.ee_type == ICMP_DEST_UNREACH &&
 	     serr->ee.ee_code == ICMP_FRAG_NEEDED)) {
 		rxrpc_adjust_mtu(peer, serr);
+		rcu_read_unlock();
 		rxrpc_free_skb(skb);
-		skb = NULL;
-		goto out;
+		rxrpc_put_peer(peer);
+		_leave(" [MTU update]");
+		return;
 	}
 
-out:
+	rxrpc_store_error(peer, serr);
 	rcu_read_unlock();
-	rxrpc_put_peer(peer);
+	rxrpc_free_skb(skb);
 
-	if (skb) {
-		/* pass the transport ref to error_handler to release */
-		skb_queue_tail(&trans->error_queue, skb);
-		rxrpc_queue_work(&trans->error_handler);
-	} else {
-		rxrpc_put_transport(trans);
-	}
+	/* The ref we obtained is passed off to the work item */
+	rxrpc_queue_work(&peer->error_distributor);
 	_leave("");
 }
 
 /*
- * deal with UDP error messages
+ * Map an error report to error codes on the peer record.
  */
-void rxrpc_UDP_error_handler(struct work_struct *work)
+static void rxrpc_store_error(struct rxrpc_peer *peer,
+			      struct sock_exterr_skb *serr)
 {
 	struct sock_extended_err *ee;
-	struct sock_exterr_skb *serr;
-	struct rxrpc_transport *trans =
-		container_of(work, struct rxrpc_transport, error_handler);
-	struct sk_buff *skb;
 	int err;
 
 	_enter("");
 
-	skb = skb_dequeue(&trans->error_queue);
-	if (!skb)
-		return;
-
-	serr = SKB_EXT_ERR(skb);
 	ee = &serr->ee;
 
 	_net("Rx Error o=%d t=%d c=%d e=%d",
@@ -244,47 +225,57 @@ void rxrpc_UDP_error_handler(struct work_struct *work)
 		}
 		break;
 
+	case SO_EE_ORIGIN_NONE:
 	case SO_EE_ORIGIN_LOCAL:
 		_proto("Rx Received local error { error=%d }", err);
+		err += RXRPC_LOCAL_ERROR_OFFSET;
 		break;
 
-	case SO_EE_ORIGIN_NONE:
 	case SO_EE_ORIGIN_ICMP6:
 	default:
 		_proto("Rx Received error report { orig=%u }", ee->ee_origin);
 		break;
 	}
 
-	/* terminate all the affected calls if there's an unrecoverable
-	 * error */
-	if (err) {
-		struct rxrpc_call *call, *_n;
+	peer->error_report = err;
+}
+
+/*
+ * Distribute an error that occurred on a peer
+ */
+void rxrpc_peer_error_distributor(struct work_struct *work)
+{
+	struct rxrpc_peer *peer =
+		container_of(work, struct rxrpc_peer, error_distributor);
+	struct rxrpc_call *call;
+	int error_report;
+
+	_enter("");
 
-		_debug("ISSUE ERROR %d", err);
+	error_report = READ_ONCE(peer->error_report);
 
-		spin_lock_bh(&trans->peer->lock);
-		trans->peer->net_error = err;
+	_debug("ISSUE ERROR %d", error_report);
 
-		list_for_each_entry_safe(call, _n, &trans->peer->error_targets,
-					 error_link) {
-			write_lock(&call->state_lock);
-			if (call->state != RXRPC_CALL_COMPLETE &&
-			    call->state < RXRPC_CALL_NETWORK_ERROR) {
-				call->state = RXRPC_CALL_NETWORK_ERROR;
-				set_bit(RXRPC_CALL_EV_RCVD_ERROR, &call->events);
-				rxrpc_queue_call(call);
-			}
-			write_unlock(&call->state_lock);
-			list_del_init(&call->error_link);
-		}
+	spin_lock_bh(&peer->lock);
 
-		spin_unlock_bh(&trans->peer->lock);
+	while (!hlist_empty(&peer->error_targets)) {
+		call = hlist_entry(peer->error_targets.first,
+				   struct rxrpc_call, error_link);
+		hlist_del_init(&call->error_link);
+
+		write_lock(&call->state_lock);
+		if (call->state != RXRPC_CALL_COMPLETE &&
+		    call->state < RXRPC_CALL_NETWORK_ERROR) {
+			call->error_report = error_report;
+			call->state = RXRPC_CALL_NETWORK_ERROR;
+			set_bit(RXRPC_CALL_EV_RCVD_ERROR, &call->events);
+			rxrpc_queue_call(call);
+		}
+		write_unlock(&call->state_lock);
 	}
 
-	if (!skb_queue_empty(&trans->error_queue))
-		rxrpc_queue_work(&trans->error_handler);
+	spin_unlock_bh(&peer->lock);
 
-	rxrpc_free_skb(skb);
-	rxrpc_put_transport(trans);
+	rxrpc_put_peer(peer);
 	_leave("");
 }