-Put the optimized soreceive_stream() under a compile time option called

TCP_SORECEIVE_STREAM for the time being.

Requested by:	brooks

Once compiled in make it easily switchable for testers by using a tuneable
 net.inet.tcp.soreceive_stream
and a corresponding read-only sysctl to report the current state.

Suggested by:	rwatson

MFC after:	2 days
-This line, and those below, will be ignored--
> Description of fields to fill in above:                     76 columns --|
> PR:            If a GNATS PR is affected by the change.
> Submitted by:  If someone else sent in the change.
> Reviewed by:   If someone else reviewed your modification.
> Approved by:   If you needed approval for this commit.
> Obtained from: If the change is from a third party.
> MFC after:     N [day[s]|week[s]|month[s]].  Request a reminder email.
> Security:      Vulnerability reference (one per line) or description.
> Empty fields above will be automatically removed.

M    sys/conf/options
M    sys/kern/uipc_socket.c
M    sys/netinet/tcp_subr.c
M    sys/netinet/tcp_usrreq.c

1 files changed, 14 insertions, 0 deletions

diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 622c508..22b2ace 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -259,6 +259,12 @@ SYSCTL_VNET_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW,
     &VNET_NAME(tcp_inflight_stab), 0,
     "Inflight Algorithm Stabilization 20 = 2 packets");
 
+#ifdef TCP_SORECEIVE_STREAM
+static int	tcp_soreceive_stream = 0;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, soreceive_stream, CTLFLAG_RDTUN,
+    &tcp_soreceive_stream, 0, "Using soreceive_stream for TCP sockets");
+#endif
+
 VNET_DEFINE(uma_zone_t, sack_hole_zone);
 #define	V_sack_hole_zone		VNET(sack_hole_zone)
 
@@ -420,6 +426,14 @@ tcp_init(void)
 	tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT;
 	tcp_tcbhashsize = hashsize;
 
+#ifdef TCP_SORECEIVE_STREAM
+	TUNABLE_INT_FETCH("net.inet.tcp.soreceive_stream", &tcp_soreceive_stream);
+	if (tcp_soreceive_stream) {
+		tcp_usrreqs.pru_soreceive = soreceive_stream;
+		tcp6_usrreqs.pru_soreceive = soreceive_stream;
+	}
+#endif
+
 #ifdef INET6
 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
 #else /* INET6 */