[PATCH v3 10/16] flow,tcp: Generalise TCP epoll_ref to generic flows

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

TCP uses three different epoll object types: one for connected sockets, one
for timers and one for listening sockets.  Listening sockets really need
information that's specific to TCP, so need their own epoll_ref field.
Timers and connected sockets, however, only need the connection (flow)
they're associated with.  As we expand the use of the flow table, we expect
that to be true for more epoll fds.  So, rename the "TCP" epoll_ref field
to be a "flow" epoll_ref field that can be used both for TCP and for other
future cases.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 passt.h      |  6 +++---
 tcp.c        | 10 +++++-----
 tcp_splice.c |  4 ++--
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/passt.h b/passt.h
index 0fce637..66a819f 100644
--- a/passt.h
+++ b/passt.h
@@ -76,8 +76,8 @@ enum epoll_type {
  * union epoll_ref - Breakdown of reference for epoll fd bookkeeping
  * @type:	Type of fd (tells us what to do with events)
  * @fd:		File descriptor number (implies < 2^24 total descriptors)
- * @tcp:	TCP-specific reference part (connected sockets)
- * @tcp_listen:	TCP-specific reference part (listening sockets)
+ * @flow:	Index of the flow this fd is linked to
+ * @tcp_listen:	TCP-specific reference part for listening sockets
  * @udp:	UDP-specific reference part
  * @icmp:	ICMP-specific reference part
  * @data:	Data handled by protocol handlers
@@ -90,7 +90,7 @@ union epoll_ref {
 #define FD_REF_MAX		((int)MAX_FROM_BITS(FD_REF_BITS))
 		int32_t		fd:FD_REF_BITS;
 		union {
-			union tcp_epoll_ref tcp;
+			uint32_t flow;
 			union tcp_listen_epoll_ref tcp_listen;
 			union udp_epoll_ref udp;
 			union icmp_epoll_ref icmp;
diff --git a/tcp.c b/tcp.c
index 512baf3..e80a6aa 100644
--- a/tcp.c
+++ b/tcp.c
@@ -639,7 +639,7 @@ static int tcp_epoll_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 {
 	int m = conn->in_epoll ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
 	union epoll_ref ref = { .type = EPOLL_TYPE_TCP, .fd = conn->sock,
-				.tcp.index = FLOW_IDX(conn) };
+				.flow = FLOW_IDX(conn) };
 	struct epoll_event ev = { .data.u64 = ref.u64 };
 
 	if (conn->events == CLOSED) {
@@ -660,7 +660,7 @@ static int tcp_epoll_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 	if (conn->timer != -1) {
 		union epoll_ref ref_t = { .type = EPOLL_TYPE_TCP_TIMER,
 					  .fd = conn->sock,
-					  .tcp.index = FLOW_IDX(conn) };
+					  .flow = FLOW_IDX(conn) };
 		struct epoll_event ev_t = { .data.u64 = ref_t.u64,
 					    .events = EPOLLIN | EPOLLET };
 
@@ -688,7 +688,7 @@ static void tcp_timer_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 	if (conn->timer == -1) {
 		union epoll_ref ref = { .type = EPOLL_TYPE_TCP_TIMER,
 					.fd = conn->sock,
-					.tcp.index = FLOW_IDX(conn) };
+					.flow = FLOW_IDX(conn) };
 		struct epoll_event ev = { .data.u64 = ref.u64,
 					  .events = EPOLLIN | EPOLLET };
 		int fd;
@@ -2760,7 +2760,7 @@ void tcp_listen_handler(struct ctx *c, union epoll_ref ref,
 void tcp_timer_handler(struct ctx *c, union epoll_ref ref)
 {
 	struct itimerspec check_armed = { { 0 }, { 0 } };
-	struct tcp_tap_conn *conn = CONN(ref.tcp.index);
+	struct tcp_tap_conn *conn = CONN(ref.flow);
 
 	if (c->no_tcp)
 		return;
@@ -2874,7 +2874,7 @@ static void tcp_tap_sock_handler(struct ctx *c, struct tcp_tap_conn *conn,
  */
 void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events)
 {
-	union flow *flow = flowtab + ref.tcp.index;
+	union flow *flow = FLOW(ref.flow);
 
 	switch (flow->f.type) {
 	case FLOW_TCP:
diff --git a/tcp_splice.c b/tcp_splice.c
index 28b91e1..5ebc4e5 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -128,8 +128,8 @@ static int tcp_splice_epoll_ctl(const struct ctx *c,
 {
 	int m = conn->in_epoll ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
 	union epoll_ref ref[SIDES] = {
-		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[0], .tcp.index = FLOW_IDX(conn) },
-		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[1], .tcp.index = FLOW_IDX(conn) }
+		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[0], .flow = FLOW_IDX(conn) },
+		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[1], .flow = FLOW_IDX(conn) }
 	};
 	struct epoll_event ev[SIDES] = { { .data.u64 = ref[0].u64 },
 					 { .data.u64 = ref[1].u64 } };
-- 
@@ -128,8 +128,8 @@ static int tcp_splice_epoll_ctl(const struct ctx *c,
 {
 	int m = conn->in_epoll ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
 	union epoll_ref ref[SIDES] = {
-		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[0], .tcp.index = FLOW_IDX(conn) },
-		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[1], .tcp.index = FLOW_IDX(conn) }
+		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[0], .flow = FLOW_IDX(conn) },
+		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[1], .flow = FLOW_IDX(conn) }
 	};
 	struct epoll_event ev[SIDES] = { { .data.u64 = ref[0].u64 },
 					 { .data.u64 = ref[1].u64 } };
-- 
2.43.0