tcp, tcp_splice: Avoid double layered dispatch for connected TCP sockets

Currently connected TCP sockets have the same epoll type, whether they're
for a "tap" connection or a spliced connection.  This means that
tcp_sock_handler() has to do a secondary check on the type of the
connection to call the right function.  We can avoid this by adding a new
epoll type and dispatching directly to the right thing.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 9 insertions, 7 deletions

diff --git a/tcp_splice.c b/tcp_splice.c
index a7d577a..33bbef1 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -127,9 +127,9 @@ static int tcp_splice_epoll_ctl(const struct ctx *c,
 {
 	int m = conn->in_epoll ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
 	const union epoll_ref ref[SIDES] = {
-		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[0],
+		{ .type = EPOLL_TYPE_TCP_SPLICE, .fd = conn->s[0],
 		  .flowside = FLOW_SIDX(conn, 0) },
-		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[1],
+		{ .type = EPOLL_TYPE_TCP_SPLICE, .fd = conn->s[1],
 		  .flowside = FLOW_SIDX(conn, 1) }
 	};
 	struct epoll_event ev[SIDES] = { { .data.u64 = ref[0].u64 },
@@ -484,18 +484,20 @@ bool tcp_splice_conn_from_sock(const struct ctx *c,
 /**
  * tcp_splice_sock_handler() - Handler for socket mapped to spliced connection
  * @c:		Execution context
- * @conn:	Connection state
- * @side:	Side of the connection on which an event has occurred
+ * @ref:	epoll reference
  * @events:	epoll events bitmap
  *
  * #syscalls:pasta splice
  */
-void tcp_splice_sock_handler(struct ctx *c, struct tcp_splice_conn *conn,
-			     int side, uint32_t events)
+void tcp_splice_sock_handler(struct ctx *c, union epoll_ref ref,
+			     uint32_t events)
 {
+	struct tcp_splice_conn *conn = CONN(ref.flowside.flow);
+	unsigned side = ref.flowside.side, fromside;
 	uint8_t lowat_set_flag, lowat_act_flag;
 	int eof, never_read;
-	unsigned fromside;
+
+	ASSERT(conn->f.type == FLOW_TCP_SPLICE);
 
 	if (conn->events == SPLICE_CLOSED)
 		return;