UDP: further performance improvements on tx

Cumulative throughput while running 64
  netperf -H $DUT -t UDP_STREAM -- -m 1
on a 2x8x2 SKL went from 1.1Mpps to 2.5Mpps

Single stream throughput increases from 910kpps to 1.18Mpps

Baseline:
https://people.freebsd.org/~mmacy/2018.05.11/udpsender2.svg

- Protect read access to global ifnet list with epoch
https://people.freebsd.org/~mmacy/2018.05.11/udpsender3.svg

- Protect short lived ifaddr references with epoch
https://people.freebsd.org/~mmacy/2018.05.11/udpsender4.svg

- Convert if_afdata read lock path to epoch
https://people.freebsd.org/~mmacy/2018.05.11/udpsender5.svg

A fix for the inpcbhash contention is pending sufficient time
on a canary at LLNW.

Reviewed by:	gallatin
Sponsored by:	Limelight Networks
Differential Revision:	https://reviews.freebsd.org/D15409

1 files changed, 2 insertions, 2 deletions

diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c
index d56f23e679e8..586259f28315 100644
--- a/sys/compat/linprocfs/linprocfs.c
+++ b/sys/compat/linprocfs/linprocfs.c
@@ -1138,7 +1138,7 @@ linux_ifname(struct ifnet *ifp, char *buffer, size_t buflen)
 
 	/* Determine the (relative) unit number for ethernet interfaces */
 	ethno = 0;
-	TAILQ_FOREACH(ifscan, &V_ifnet, if_link) {
+	CK_STAILQ_FOREACH(ifscan, &V_ifnet, if_link) {
 		if (ifscan == ifp)
 			return (snprintf(buffer, buflen, "eth%d", ethno));
 		if (IFP_IS_ETH(ifscan))
@@ -1166,7 +1166,7 @@ linprocfs_donetdev(PFS_FILL_ARGS)
 
 	CURVNET_SET(TD_TO_VNET(curthread));
 	IFNET_RLOCK();
-	TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
+	CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
 		linux_ifname(ifp, ifname, sizeof ifname);
 		sbuf_printf(sb, "%6.6s: ", ifname);
 		sbuf_printf(sb, "%7ju %7ju %4ju %4ju %4lu %5lu %10lu %9ju ",