[NETROM]: Implement G8PZT Circuit reset for NET/ROM

NET/ROM is lacking a connection reset like TCP's RST flag which at times
may result in a connecting having to slowly timing out instead of just being
reset.  An earlier attempt to reset the connection by sending a
NR_CONNACK | NR_CHOKE_FLAG transport was inacceptable as it did result in
crashes of BPQ systems.  An alternative approach of introducing a new
transport type 7 (NR_RESET) has be implemented several years ago in
Paula Jayne Dowie G8PZT's Xrouter.

Implement NR_RESET for Linux's NET/ROM but like any messing with the state
engine consider this experimental for now and thus control it by a sysctl
(net.netrom.reset) which for the time being defaults to off.

Signed-off-by: Ralf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 0 deletions

diff --git a/net/netrom/nr_in.c b/net/netrom/nr_in.c
index 64b81a796907..004e8599b8fe 100644
--- a/net/netrom/nr_in.c
+++ b/net/netrom/nr_in.c
@@ -98,6 +98,11 @@ static int nr_state1_machine(struct sock *sk, struct sk_buff *skb,
                 nr_disconnect(sk, ECONNREFUSED);
                 break;
 
+        case NR_RESET:
+                if (sysctl_netrom_reset_circuit);
+                        nr_disconnect(sk, ECONNRESET);
+                break;
+
         default:
                 break;
         }
@@ -124,6 +129,11 @@ static int nr_state2_machine(struct sock *sk, struct sk_buff *skb,
                 nr_disconnect(sk, 0);
                 break;
 
+        case NR_RESET:
+                if (sysctl_netrom_reset_circuit);
+                        nr_disconnect(sk, ECONNRESET);
+                break;
+
         default:
                 break;
         }
@@ -254,6 +264,11 @@ static int nr_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype
                 }
                 break;
 
+        case NR_RESET:
+                if (sysctl_netrom_reset_circuit);
+                        nr_disconnect(sk, ECONNRESET);
+                break;
+
         default:
                 break;
         }