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 <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
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fbe81decbd
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3 changed files with 62 additions and 29 deletions
34
tcp.c
34
tcp.c
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@ -1792,7 +1792,7 @@ int tcp_conn_pool_sock(int pool[])
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*
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*
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* Return: socket number on success, negative code if socket creation failed
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* Return: socket number on success, negative code if socket creation failed
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*/
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*/
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int tcp_conn_new_sock(const struct ctx *c, sa_family_t af)
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static int tcp_conn_new_sock(const struct ctx *c, sa_family_t af)
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{
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{
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int s;
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int s;
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@ -1811,6 +1811,32 @@ int tcp_conn_new_sock(const struct ctx *c, sa_family_t af)
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return s;
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return s;
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}
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}
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/**
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* tcp_conn_sock() - Obtain a connectable socket in the host/init namespace
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* @c: Execution context
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* @af: Address family (AF_INET or AF_INET6)
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*
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* Return: Socket fd on success, -errno on failure
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*/
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int tcp_conn_sock(const struct ctx *c, sa_family_t af)
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{
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int *pool = af == AF_INET6 ? init_sock_pool6 : init_sock_pool4;
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int s;
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if ((s = tcp_conn_pool_sock(pool)) >= 0)
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return s;
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/* If the pool is empty we just open a new one without refilling the
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* pool to keep latency down.
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*/
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if ((s = tcp_conn_new_sock(c, af)) >= 0)
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return s;
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err("TCP: Unable to open socket for new connection: %s",
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strerror(-s));
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return -1;
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}
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/**
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/**
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* tcp_conn_tap_mss() - Get MSS value advertised by tap/guest
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* tcp_conn_tap_mss() - Get MSS value advertised by tap/guest
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* @conn: Connection pointer
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* @conn: Connection pointer
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@ -1909,7 +1935,6 @@ static void tcp_conn_from_tap(struct ctx *c, sa_family_t af,
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const struct tcphdr *th, const char *opts,
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const struct tcphdr *th, const char *opts,
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size_t optlen, const struct timespec *now)
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size_t optlen, const struct timespec *now)
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{
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{
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int *pool = af == AF_INET6 ? init_sock_pool6 : init_sock_pool4;
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struct sockaddr_in addr4 = {
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struct sockaddr_in addr4 = {
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.sin_family = AF_INET,
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.sin_family = AF_INET,
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.sin_port = th->dest,
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.sin_port = th->dest,
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@ -1931,9 +1956,8 @@ static void tcp_conn_from_tap(struct ctx *c, sa_family_t af,
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if (!(flow = flow_alloc()))
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if (!(flow = flow_alloc()))
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return;
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return;
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if ((s = tcp_conn_pool_sock(pool)) < 0)
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if ((s = tcp_conn_sock(c, af)) < 0)
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if ((s = tcp_conn_new_sock(c, af)) < 0)
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goto cancel;
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goto cancel;
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if (!c->no_map_gw) {
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if (!c->no_map_gw) {
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if (af == AF_INET && IN4_ARE_ADDR_EQUAL(daddr, &c->ip4.gw))
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if (af == AF_INET && IN4_ARE_ADDR_EQUAL(daddr, &c->ip4.gw))
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@ -159,7 +159,7 @@ bool tcp_flow_defer(union flow *flow);
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bool tcp_splice_flow_defer(union flow *flow);
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bool tcp_splice_flow_defer(union flow *flow);
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void tcp_splice_timer(const struct ctx *c, union flow *flow);
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void tcp_splice_timer(const struct ctx *c, union flow *flow);
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int tcp_conn_pool_sock(int pool[]);
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int tcp_conn_pool_sock(int pool[]);
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int tcp_conn_new_sock(const struct ctx *c, sa_family_t af);
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int tcp_conn_sock(const struct ctx *c, sa_family_t af);
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int tcp_sock_refill_pool(const struct ctx *c, int pool[], sa_family_t af);
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int tcp_sock_refill_pool(const struct ctx *c, int pool[], sa_family_t af);
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void tcp_splice_refill(const struct ctx *c);
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void tcp_splice_refill(const struct ctx *c);
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55
tcp_splice.c
55
tcp_splice.c
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@ -376,6 +376,34 @@ static int tcp_splice_connect(const struct ctx *c, struct tcp_splice_conn *conn,
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return 0;
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return 0;
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}
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}
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/**
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* tcp_conn_sock_ns() - Obtain a connectable socket in the namespace
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* @c: Execution context
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* @af: Address family (AF_INET or AF_INET6)
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*
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* Return: Socket fd in the namespace on success, -errno on failure
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*/
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static int tcp_conn_sock_ns(const struct ctx *c, sa_family_t af)
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{
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int *p = af == AF_INET6 ? ns_sock_pool6 : ns_sock_pool4;
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int s;
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if ((s = tcp_conn_pool_sock(p)) >= 0)
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return s;
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/* If the pool is empty we have to incur the latency of entering the ns.
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* Therefore, we might as well refill the whole pool while we're at it.
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* This differs from tcp_conn_sock().
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*/
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NS_CALL(tcp_sock_refill_ns, c);
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if ((s = tcp_conn_pool_sock(p)) >= 0)
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return s;
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err("TCP: No available ns sockets for new connection");
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return -1;
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}
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/**
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/**
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* tcp_splice_new() - Handle new spliced connection
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* tcp_splice_new() - Handle new spliced connection
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* @c: Execution context
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* @c: Execution context
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@ -388,38 +416,19 @@ static int tcp_splice_connect(const struct ctx *c, struct tcp_splice_conn *conn,
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static int tcp_splice_new(const struct ctx *c, struct tcp_splice_conn *conn,
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static int tcp_splice_new(const struct ctx *c, struct tcp_splice_conn *conn,
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in_port_t port, uint8_t pif)
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in_port_t port, uint8_t pif)
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{
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{
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sa_family_t af = CONN_V6(conn) ? AF_INET6 : AF_INET;
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int s = -1;
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int s = -1;
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/* If the pool is empty we take slightly different approaches
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* for init or ns sockets. For init sockets we just open a
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* new one without refilling the pool to keep latency down.
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* For ns sockets, we're going to incur the latency of
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* entering the ns anyway, so we might as well refill the
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* pool.
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*/
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if (pif == PIF_SPLICE) {
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if (pif == PIF_SPLICE) {
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int *p = CONN_V6(conn) ? init_sock_pool6 : init_sock_pool4;
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s = tcp_conn_sock(c, af);
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sa_family_t af = CONN_V6(conn) ? AF_INET6 : AF_INET;
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s = tcp_conn_pool_sock(p);
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if (s < 0)
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s = tcp_conn_new_sock(c, af);
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} else {
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} else {
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int *p = CONN_V6(conn) ? ns_sock_pool6 : ns_sock_pool4;
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ASSERT(pif == PIF_HOST);
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ASSERT(pif == PIF_HOST);
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/* If pool is empty, refill it first */
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s = tcp_conn_sock_ns(c, af);
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if (p[TCP_SOCK_POOL_SIZE-1] < 0)
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NS_CALL(tcp_sock_refill_ns, c);
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s = tcp_conn_pool_sock(p);
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}
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}
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if (s < 0) {
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if (s < 0)
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warn("Couldn't open connectable socket for splice (%d)", s);
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return s;
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return s;
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}
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return tcp_splice_connect(c, conn, s, port);
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return tcp_splice_connect(c, conn, s, port);
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}
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}
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