From 3f1f4f0e73b6d12c01e8cad4791d23e8e56127db Mon Sep 17 00:00:00 2001 From: jch Date: Mon, 18 Jul 2016 08:20:31 +0000 Subject: MFC r261242: Decrease lock contention within the TCP accept case by removing the INP_INFO lock from tcp_usr_accept. As the PR/patch states this was following the advice already in the code. See the PR below for a full discussion of this change and its measured effects. PR: 183659 Submitted by: Julien Charbon Reviewed by: jhb --- sys/netinet/tcp_syncache.c | 4 +++- sys/netinet/tcp_usrreq.c | 9 --------- 2 files changed, 3 insertions(+), 10 deletions(-) diff --git a/sys/netinet/tcp_syncache.c b/sys/netinet/tcp_syncache.c index 0398b03..03e8c72 100644 --- a/sys/netinet/tcp_syncache.c +++ b/sys/netinet/tcp_syncache.c @@ -683,7 +683,7 @@ syncache_socket(struct syncache *sc, struct socket *lso, struct mbuf *m) * connection when the SYN arrived. If we can't create * the connection, abort it. */ - so = sonewconn(lso, SS_ISCONNECTED); + so = sonewconn(lso, 0); if (so == NULL) { /* * Drop the connection; we will either send a RST or @@ -922,6 +922,8 @@ syncache_socket(struct syncache *sc, struct socket *lso, struct mbuf *m) INP_WUNLOCK(inp); + soisconnected(so); + TCPSTAT_INC(tcps_accepts); return (so); diff --git a/sys/netinet/tcp_usrreq.c b/sys/netinet/tcp_usrreq.c index 1ccbf9a..8d7e9a0 100644 --- a/sys/netinet/tcp_usrreq.c +++ b/sys/netinet/tcp_usrreq.c @@ -643,13 +643,6 @@ out: /* * Accept a connection. Essentially all the work is done at higher levels; * just return the address of the peer, storing through addr. - * - * The rationale for acquiring the tcbinfo lock here is somewhat complicated, - * and is described in detail in the commit log entry for r175612. Acquiring - * it delays an accept(2) racing with sonewconn(), which inserts the socket - * before the inpcb address/port fields are initialized. A better fix would - * prevent the socket from being placed in the listen queue until all fields - * are fully initialized. */ static int tcp_usr_accept(struct socket *so, struct sockaddr **nam) @@ -666,7 +659,6 @@ tcp_usr_accept(struct socket *so, struct sockaddr **nam) inp = sotoinpcb(so); KASSERT(inp != NULL, ("tcp_usr_accept: inp == NULL")); - INP_INFO_RLOCK(&V_tcbinfo); INP_WLOCK(inp); if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) { error = ECONNABORTED; @@ -686,7 +678,6 @@ tcp_usr_accept(struct socket *so, struct sockaddr **nam) out: TCPDEBUG2(PRU_ACCEPT); INP_WUNLOCK(inp); - INP_INFO_RUNLOCK(&V_tcbinfo); if (error == 0) *nam = in_sockaddr(port, &addr); return error; -- cgit v1.1