[PATCH 7/9] epoll: Split handling of listening TCP sockets into their own handler

[David Gibson <david@gibson.dropbear.id.au>]

tcp_sock_handler() handles both listening TCP sockets, and connected TCP
sockets, but what it needs to do in those cases has essentially nothing in
common.  Therefore, give listening sockets their own epoll_type value and
dispatch directly to their own handler from the top level.  This also lets
us remove the listen field from tcp_epoll_ref, since the information it
carries is implicit in the epoll_type.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 passt.c |  8 ++++++--
 passt.h |  4 +++-
 tcp.c   | 31 +++++++++----------------------
 tcp.h   |  8 ++++----
 util.c  |  2 +-
 5 files changed, 23 insertions(+), 30 deletions(-)

diff --git a/passt.c b/passt.c
index c750fad..c32981d 100644
--- a/passt.c
+++ b/passt.c
@@ -56,7 +56,8 @@
 char pkt_buf[PKT_BUF_BYTES]	__attribute__ ((aligned(PAGE_SIZE)));
 
 char *epoll_type_str[EPOLL_TYPE_MAX+1] = {
-	[EPOLL_TYPE_TCP]	= "TCP socket",
+	[EPOLL_TYPE_TCP]	= "connected TCP socket",
+	[EPOLL_TYPE_TCP_LISTEN]	= "listening TCP socket",
 	[EPOLL_TYPE_TCP_TIMER]	= "TCP timer",
 	[EPOLL_TYPE_UDP]	= "UDP socket",
 	[EPOLL_TYPE_ICMP]	= "ICMP socket",
@@ -323,7 +324,10 @@ loop:
 			break;
 		case EPOLL_TYPE_TCP:
 			if (!c.no_tcp)
-				tcp_sock_handler(&c, ref, eventmask, &now);
+				tcp_sock_handler(&c, ref, eventmask);
+			break;
+		case EPOLL_TYPE_TCP_LISTEN:
+			tcp_listen_handler(&c, ref, &now);
 			break;
 		case EPOLL_TYPE_TCP_TIMER:
 			tcp_timer_handler(&c, ref);
diff --git a/passt.h b/passt.h
index fc1efdb..176bc85 100644
--- a/passt.h
+++ b/passt.h
@@ -47,8 +47,10 @@ union epoll_ref;
 enum epoll_type {
 	/* Special value to indicate an invalid type */
 	EPOLL_TYPE_NONE = 0,
-	/* TCP sockets */
+	/* Connected TCP sockets */
 	EPOLL_TYPE_TCP,
+	/* Listening TCP sockets */
+	EPOLL_TYPE_TCP_LISTEN,
 	/* timerfds used for TCP timers */
 	EPOLL_TYPE_TCP_TIMER,
 	/* UDP sockets */
diff --git a/tcp.c b/tcp.c
index 98761a2..c237393 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2765,22 +2765,20 @@ static void tcp_tap_conn_from_sock(struct ctx *c, union epoll_ref ref,
 }
 
 /**
- * tcp_conn_from_sock() - Handle new connection request from listening socket
+ * tcp_listen_handler() - Handle new connection request from listening socket
  * @c:		Execution context
  * @ref:	epoll reference of listening socket
  * @now:	Current timestamp
  */
-static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
-			       const struct timespec *now)
+void tcp_listen_handler(struct ctx *c, union epoll_ref ref,
+			const struct timespec *now)
 {
 	struct sockaddr_storage sa;
 	union tcp_conn *conn;
 	socklen_t sl;
 	int s;
 
-	ASSERT(ref.tcp.listen);
-
-	if (c->tcp.conn_count >= TCP_MAX_CONNS)
+	if (c->no_tcp || c->tcp.conn_count >= TCP_MAX_CONNS)
 		return;
 
 	sl = sizeof(sa);
@@ -2926,19 +2924,10 @@ static void tcp_tap_sock_handler(struct ctx *c, struct tcp_tap_conn *conn,
  * @c:		Execution context
  * @ref:	epoll reference
  * @events:	epoll events bitmap
- * @now:	Current timestamp
  */
-void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
-		      const struct timespec *now)
+void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events)
 {
-	union tcp_conn *conn;
-
-	if (ref.tcp.listen) {
-		tcp_conn_from_sock(c, ref, now);
-		return;
-	}
-
-	conn = tc + ref.tcp.index;
+	union tcp_conn *conn = tc + ref.tcp.index;
 
 	if (conn->c.spliced)
 		tcp_splice_sock_handler(c, &conn->splice, ref.fd, events);
@@ -2960,7 +2949,7 @@ static int tcp_sock_init_af(const struct ctx *c, int af, in_port_t port,
 			    const struct in_addr *addr, const char *ifname)
 {
 	in_port_t idx = port + c->tcp.fwd_in.delta[port];
-	union tcp_epoll_ref tref = { .listen = 1, .index = idx };
+	union tcp_epoll_ref tref = { .index = idx };
 	int s;
 
 	s = sock_l4(c, af, IPPROTO_TCP, addr, ifname, port, tref.u32);
@@ -3020,8 +3009,7 @@ int tcp_sock_init(const struct ctx *c, sa_family_t af, const void *addr,
 static void tcp_ns_sock_init4(const struct ctx *c, in_port_t port)
 {
 	in_port_t idx = port + c->tcp.fwd_out.delta[port];
-	union tcp_epoll_ref tref = { .listen = 1, .outbound = 1,
-				     .index = idx };
+	union tcp_epoll_ref tref = { .outbound = 1, .index = idx };
 	struct in_addr loopback = { htonl(INADDR_LOOPBACK) };
 	int s;
 
@@ -3045,8 +3033,7 @@ static void tcp_ns_sock_init4(const struct ctx *c, in_port_t port)
 static void tcp_ns_sock_init6(const struct ctx *c, in_port_t port)
 {
 	in_port_t idx = port + c->tcp.fwd_out.delta[port];
-	union tcp_epoll_ref tref = { .listen = 1, .outbound = 1,
-				     .index = idx };
+	union tcp_epoll_ref tref = { .outbound = 1, .index = idx };
 	int s;
 
 	ASSERT(c->mode == MODE_PASTA);
diff --git a/tcp.h b/tcp.h
index 8eb7782..8189ac0 100644
--- a/tcp.h
+++ b/tcp.h
@@ -14,8 +14,9 @@
 struct ctx;
 
 void tcp_timer_handler(struct ctx *c, union epoll_ref ref);
-void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
-		      const struct timespec *now);
+void tcp_listen_handler(struct ctx *c, union epoll_ref ref,
+			const struct timespec *now);
+void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events);
 int tcp_tap_handler(struct ctx *c, int af, const void *addr,
 		    const struct pool *p, const struct timespec *now);
 int tcp_sock_init(const struct ctx *c, sa_family_t af, const void *addr,
@@ -37,8 +38,7 @@ void tcp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s,
  */
 union tcp_epoll_ref {
 	struct {
-		uint32_t	listen:1,
-				outbound:1,
+		uint32_t	outbound:1,
 				index:20;
 	};
 	uint32_t u32;
diff --git a/util.c b/util.c
index 2cac7ba..d965f48 100644
--- a/util.c
+++ b/util.c
@@ -120,7 +120,7 @@ int sock_l4(const struct ctx *c, int af, uint8_t proto,
 
 	switch (proto) {
 	case IPPROTO_TCP:
-		ref.type = EPOLL_TYPE_TCP;
+		ref.type = EPOLL_TYPE_TCP_LISTEN;
 		break;
 	case IPPROTO_UDP:
 		ref.type = EPOLL_TYPE_UDP;
-- 
@@ -120,7 +120,7 @@ int sock_l4(const struct ctx *c, int af, uint8_t proto,
 
 	switch (proto) {
 	case IPPROTO_TCP:
-		ref.type = EPOLL_TYPE_TCP;
+		ref.type = EPOLL_TYPE_TCP_LISTEN;
 		break;
 	case IPPROTO_UDP:
 		ref.type = EPOLL_TYPE_UDP;
-- 
2.41.0