From fe27ebce5c59c7fc684c5affa6ce27fdc32d362d Mon Sep 17 00:00:00 2001 From: David Gibson Date: Mon, 19 Feb 2024 18:56:50 +1100 Subject: tcp, tcp_splice: Helpers for getting sockets from the pools We maintain pools of ready-to-connect sockets in both the original and (for pasta) guest namespace to reduce latency when starting new TCP connections. If we exhaust those pools we have to take a higher latency path to get a new socket. Currently we open-code that fallback in the places we need it. To improve clarity encapsulate that into helper functions. While we're at it, give those helpers clearer error reporting. Signed-off-by: David Gibson Signed-off-by: Stefano Brivio --- tcp_splice.c | 55 ++++++++++++++++++++++++++++++++----------------------- 1 file changed, 32 insertions(+), 23 deletions(-) (limited to 'tcp_splice.c') diff --git a/tcp_splice.c b/tcp_splice.c index ee68029..5b38a82 100644 --- a/tcp_splice.c +++ b/tcp_splice.c @@ -376,6 +376,34 @@ static int tcp_splice_connect(const struct ctx *c, struct tcp_splice_conn *conn, return 0; } +/** + * tcp_conn_sock_ns() - Obtain a connectable socket in the namespace + * @c: Execution context + * @af: Address family (AF_INET or AF_INET6) + * + * Return: Socket fd in the namespace on success, -errno on failure + */ +static int tcp_conn_sock_ns(const struct ctx *c, sa_family_t af) +{ + int *p = af == AF_INET6 ? ns_sock_pool6 : ns_sock_pool4; + int s; + + if ((s = tcp_conn_pool_sock(p)) >= 0) + return s; + + /* If the pool is empty we have to incur the latency of entering the ns. + * Therefore, we might as well refill the whole pool while we're at it. + * This differs from tcp_conn_sock(). + */ + NS_CALL(tcp_sock_refill_ns, c); + + if ((s = tcp_conn_pool_sock(p)) >= 0) + return s; + + err("TCP: No available ns sockets for new connection"); + return -1; +} + /** * tcp_splice_new() - Handle new spliced connection * @c: Execution context @@ -388,38 +416,19 @@ static int tcp_splice_connect(const struct ctx *c, struct tcp_splice_conn *conn, static int tcp_splice_new(const struct ctx *c, struct tcp_splice_conn *conn, in_port_t port, uint8_t pif) { + sa_family_t af = CONN_V6(conn) ? AF_INET6 : AF_INET; int s = -1; - /* If the pool is empty we take slightly different approaches - * for init or ns sockets. For init sockets we just open a - * new one without refilling the pool to keep latency down. - * For ns sockets, we're going to incur the latency of - * entering the ns anyway, so we might as well refill the - * pool. - */ if (pif == PIF_SPLICE) { - int *p = CONN_V6(conn) ? init_sock_pool6 : init_sock_pool4; - sa_family_t af = CONN_V6(conn) ? AF_INET6 : AF_INET; - - s = tcp_conn_pool_sock(p); - if (s < 0) - s = tcp_conn_new_sock(c, af); + s = tcp_conn_sock(c, af); } else { - int *p = CONN_V6(conn) ? ns_sock_pool6 : ns_sock_pool4; - ASSERT(pif == PIF_HOST); - /* If pool is empty, refill it first */ - if (p[TCP_SOCK_POOL_SIZE-1] < 0) - NS_CALL(tcp_sock_refill_ns, c); - - s = tcp_conn_pool_sock(p); + s = tcp_conn_sock_ns(c, af); } - if (s < 0) { - warn("Couldn't open connectable socket for splice (%d)", s); + if (s < 0) return s; - } return tcp_splice_connect(c, conn, s, port); } -- cgit v1.2.3