[DCCP]: Dedicated auxiliary states to support passive-close

This adds two auxiliary states to deal with passive closes:
  * PASSIVE_CLOSE    (reached from OPEN via reception of Close)    and
  * PASSIVE_CLOSEREQ (reached from OPEN via reception of CloseReq)
as internal intermediate states.

These states are used to allow a receiver to process unread data before
acknowledging the received connection-termination-request (the Close/CloseReq).

Without such support, it will happen that passively-closed sockets enter CLOSED
state while there is still unprocessed data in the queue; leading to unexpected
and erratic API behaviour.

PASSIVE_CLOSE has been mapped into TCPF_CLOSE_WAIT, so that the code will
seamlessly work with inet_accept() (which tests for this state).

The state names are thanks to Arnaldo, who suggested this naming scheme
following an earlier revision of this patch.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 10 deletions

diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 73006b747678..3489d3f21f50 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -60,8 +60,7 @@ void dccp_set_state(struct sock *sk, const int state)
 {
         const int oldstate = sk->sk_state;
 
-        dccp_pr_debug("%s(%p) %-10.10s -> %s\n",
-                      dccp_role(sk), sk,
+        dccp_pr_debug("%s(%p)  %s  -->  %s\n", dccp_role(sk), sk,
                       dccp_state_name(oldstate), dccp_state_name(state));
         WARN_ON(state == oldstate);
 
@@ -134,14 +133,17 @@ EXPORT_SYMBOL_GPL(dccp_packet_name);
 const char *dccp_state_name(const int state)
 {
         static char *dccp_state_names[] = {
-        [DCCP_OPEN]       = "OPEN",
-        [DCCP_REQUESTING] = "REQUESTING",
-        [DCCP_PARTOPEN]   = "PARTOPEN",
-        [DCCP_LISTEN]     = "LISTEN",
-        [DCCP_RESPOND]    = "RESPOND",
-        [DCCP_CLOSING]    = "CLOSING",
-        [DCCP_TIME_WAIT]  = "TIME_WAIT",
-        [DCCP_CLOSED]     = "CLOSED",
+        [DCCP_OPEN]             = "OPEN",
+        [DCCP_REQUESTING]       = "REQUESTING",
+        [DCCP_PARTOPEN]         = "PARTOPEN",
+        [DCCP_LISTEN]           = "LISTEN",
+        [DCCP_RESPOND]          = "RESPOND",
+        [DCCP_CLOSING]          = "CLOSING",
+        [DCCP_ACTIVE_CLOSEREQ]  = "CLOSEREQ",
+        [DCCP_PASSIVE_CLOSE]    = "PASSIVE_CLOSE",
+        [DCCP_PASSIVE_CLOSEREQ] = "PASSIVE_CLOSEREQ",
+        [DCCP_TIME_WAIT]        = "TIME_WAIT",
+        [DCCP_CLOSED]           = "CLOSED",
         };
 
         if (state >= DCCP_MAX_STATES)