Author: gnn
Date: Tue Jan 28 20:28:32 2014
New Revision: 261242
URL: http://svnweb.freebsd.org/changeset/base/261242
Log:
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 disucssion of this change and its
measured effects.
PR: 183659
Submitted by: Julian Charbon
Reviewed by: jhb
Modified:
head/sys/netinet/tcp_syncache.c
head/sys/netinet/tcp_usrreq.c
Modified: head/sys/netinet/tcp_syncache.c
==============================================================================
--- head/sys/netinet/tcp_syncache.c Tue Jan 28 19:12:31 2014
(r261241)
+++ head/sys/netinet/tcp_syncache.c Tue Jan 28 20:28:32 2014
(r261242)
@@ -682,7 +682,7 @@ syncache_socket(struct syncache *sc, str
* 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, str
INP_WUNLOCK(inp);
+ soisconnected(so);
+
TCPSTAT_INC(tcps_accepts);
return (so);
Modified: head/sys/netinet/tcp_usrreq.c
==============================================================================
--- head/sys/netinet/tcp_usrreq.c Tue Jan 28 19:12:31 2014
(r261241)
+++ head/sys/netinet/tcp_usrreq.c Tue Jan 28 20:28:32 2014
(r261242)
@@ -610,13 +610,6 @@ 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)
@@ -633,7 +626,6 @@ tcp_usr_accept(struct socket *so, struct
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;
@@ -653,7 +645,6 @@ tcp_usr_accept(struct socket *so, struct
out:
TCPDEBUG2(PRU_ACCEPT);
INP_WUNLOCK(inp);
- INP_INFO_RUNLOCK(&V_tcbinfo);
if (error == 0)
*nam = in_sockaddr(port, &addr);
return error;
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