Change semantics of socket close and detach. Add a new protocol switch

function, pru_close, to notify protocols that the file descriptor or
other consumer of a socket is closing the socket.  pru_abort is now a
notification of close also, and no longer detaches.  pru_detach is no
longer used to notify of close, and will be called during socket
tear-down by sofree() when all references to a socket evaporate after
an earlier call to abort or close the socket.  This means detach is now
an unconditional teardown of a socket, whereas previously sockets could
persist after detach of the protocol retained a reference.

This faciliates sharing mutexes between layers of the network stack as
the mutex is required during the checking and removal of references at
the head of sofree().  With this change, pru_detach can now assume that
the mutex will no longer be required by the socket layer after
completion, whereas before this was not necessarily true.

Reviewed by:	gnn

1 files changed, 12 insertions, 37 deletions

diff --git a/sys/netinet/tcp_timewait.c b/sys/netinet/tcp_timewait.c
index 676b22e..64574cf 100644
--- a/sys/netinet/tcp_timewait.c
+++ b/sys/netinet/tcp_timewait.c
@@ -808,18 +808,7 @@ tcp_close(struct tcpcb *tp)
 		KASSERT(so->so_state & SS_PROTOREF,
 		    ("tcp_close: !SS_PROTOREF"));
 		inp->inp_vflag &= ~INP_SOCKREF;
-		tcp_discardcb(tp);
-#ifdef INET6
-		if (inp->inp_vflag & INP_IPV6PROTO) {
-			in6_pcbdetach(inp);
-			in6_pcbfree(inp);
-		} else {
-#endif
-			in_pcbdetach(inp);
-			in_pcbfree(inp);
-#ifdef INET6
-		}
-#endif
+		INP_UNLOCK(inp);
 		ACCEPT_LOCK();
 		SOCK_LOCK(so);
 		so->so_state &= ~SS_PROTOREF;
@@ -1789,12 +1778,6 @@ tcp_twstart(struct tcpcb *tp)
 		KASSERT(so->so_state & SS_PROTOREF,
 		    ("tcp_twstart: !SS_PROTOREF"));
 		inp->inp_vflag &= ~INP_SOCKREF;
-#ifdef INET6
-		if (inp->inp_vflag & INP_IPV6PROTO)
-			in6_pcbdetach(inp);
-		else
-#endif
-			in_pcbdetach(inp);
 		INP_UNLOCK(inp);
 		ACCEPT_LOCK();
 		SOCK_LOCK(so);
@@ -1847,12 +1830,11 @@ tcp_twclose(struct tcptw *tw, int reuse)
 	/*
 	 * At this point, we are in one of two situations:
 	 *
-	 * (1) We have no socket, just an inpcb<->twtcp pair.  Release it all
-	 * after validating.
+	 * (1) We have no socket, just an inpcb<->twtcp pair.  We can free
+	 *     all state.
 	 *
-	 * (2) We have a socket, which we may or may now own the reference
-	 * for.  If we own the reference, release all the state after
-	 * validating.  If not, leave it for the socket close to clean up.
+	 * (2) We have a socket -- if we own a reference, release it and
+	 *     notify the socket layer.
 	 */
 	inp = tw->tw_inpcb;
 	KASSERT((inp->inp_vflag & INP_TIMEWAIT), ("tcp_twclose: !timewait"));
@@ -1867,22 +1849,15 @@ tcp_twclose(struct tcptw *tw, int reuse)
 
 	so = inp->inp_socket;
 	if (so != NULL) {
+		/*
+		 * If there's a socket, handle two cases: first, we own a
+		 * strong reference, which we will now release, or we don't
+		 * in which case another reference exists (XXXRW: think
+		 * about this more), and we don't need to take action.
+		 */
 		if (inp->inp_vflag & INP_SOCKREF) {
-			/*
-			 * If a socket is present, and we own the only
-			 * reference, we need to tear down the socket and the
-			 * inpcb.
-			 */
 			inp->inp_vflag &= ~INP_SOCKREF;
-#ifdef INET6
-			if (inp->inp_vflag & INP_IPV6PROTO) {
-				in6_pcbdetach(inp);
-				in6_pcbfree(inp);
-			} else {
-				in_pcbdetach(inp);
-				in_pcbfree(inp);
-			}
-#endif
+			INP_UNLOCK(inp);
 			ACCEPT_LOCK();
 			SOCK_LOCK(so);
 			KASSERT(so->so_state & SS_PROTOREF,