Do not increase the size of the socket buffer under memory pressure.

From Simon Mages, ok beck@, claudio@, bluhm@

diff --git a/sys/netinet/tcp_usrreq.c b/sys/netinet/tcp_usrreq.c
index 964e330..6eb6efb 100644 (file)
--- a/sys/netinet/tcp_usrreq.c
+++ b/sys/netinet/tcp_usrreq.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: tcp_usrreq.c,v 1.131 2016/06/18 10:36:13 vgross Exp $ */
+/*     $OpenBSD: tcp_usrreq.c,v 1.132 2016/07/11 10:35:43 mpi Exp $    */
 /*     $NetBSD: tcp_usrreq.c,v 1.20 1996/02/13 23:44:16 christos Exp $ */
 
 /*
@@ -977,12 +977,13 @@ void
 tcp_update_sndspace(struct tcpcb *tp)
 {
        struct socket *so = tp->t_inpcb->inp_socket;
-       u_long nmax;
+       u_long nmax = so->so_snd.sb_hiwat;
 
-       if (sbchecklowmem())
+       if (sbchecklowmem()) {
                /* low on memory try to get rid of some */
-               nmax = tcp_sendspace;
-       else if (so->so_snd.sb_wat != tcp_sendspace)
+               if (tcp_sendspace < nmax)
+                       nmax = tcp_sendspace;
+       } else if (so->so_snd.sb_wat != tcp_sendspace)
                /* user requested buffer size, auto-scaling disabled */
                nmax = so->so_snd.sb_wat;
        else
@@ -1017,10 +1018,11 @@ tcp_update_rcvspace(struct tcpcb *tp)
        struct socket *so = tp->t_inpcb->inp_socket;
        u_long nmax = so->so_rcv.sb_hiwat;
 
-       if (sbchecklowmem())
+       if (sbchecklowmem()) {
                /* low on memory try to get rid of some */
-               nmax = tcp_recvspace;
-       else if (so->so_rcv.sb_wat != tcp_recvspace)
+               if (tcp_recvspace < nmax)
+                       nmax = tcp_recvspace;
+       } else if (so->so_rcv.sb_wat != tcp_recvspace)
                /* user requested buffer size, auto-scaling disabled */
                nmax = so->so_rcv.sb_wat;
        else {