add the kernel side of net.link.ifrxq.pressure_return and pressure_drop

these values are used as the backpressure thresholds in the interface
rx q processing code. theyre being exposed as tunables to userland
while we are figuring out what the best values for them are.

ok visa@ deraadt@

3 files changed, 76 insertions, 3 deletions

diff --git a/sys/kern/uipc_domain.c b/sys/kern/uipc_domain.c
index fafd5da50c7..8cb2c77dc60 100644
--- a/sys/kern/uipc_domain.c
+++ b/sys/kern/uipc_domain.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uipc_domain.c,v 1.56 2018/06/23 14:38:59 denis Exp $	*/
+/*	$OpenBSD: uipc_domain.c,v 1.57 2019/07/03 10:19:45 dlg Exp $	*/
 /*	$NetBSD: uipc_domain.c,v 1.14 1996/02/09 19:00:44 christos Exp $	*/
 
 /*
@@ -159,6 +159,37 @@ pffindproto(int family, int protocol, int type)
 	return (maybe);
 }
 
+static int
+net_link_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
+    void *newp, size_t newlen)
+{
+	int node;
+	int error;
+
+	/*
+	 * All sysctl names at this level are nonterminal.
+	 */
+	if (namelen < 2)
+		return (EISDIR);		/* overloaded */
+	node = name[0];
+
+	namelen--;
+	name++;
+
+	switch (node) {
+	case NET_LINK_IFRXQ:
+		error = net_ifiq_sysctl(name, namelen, oldp, oldlenp,
+		    newp, newlen);
+		break;
+
+	default:
+		error = ENOPROTOOPT;
+		break;
+	}
+
+	return (error);
+}
+
 int
 net_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
     size_t newlen, struct proc *p)
@@ -178,6 +209,9 @@ net_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
 
 	if (family == PF_UNSPEC)
 		return (0);
+	if (family == PF_LINK)
+		return (net_link_sysctl(name + 1, namelen - 1, oldp, oldlenp,
+		    newp, newlen));
 #if NBPFILTER > 0
 	if (family == PF_BPF)
 		return (bpf_sysctl(name + 1, namelen - 1, oldp, oldlenp,
diff --git a/sys/net/ifq.c b/sys/net/ifq.c
index bd0764e907f..302277c2e7b 100644
--- a/sys/net/ifq.c
+++ b/sys/net/ifq.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ifq.c,v 1.32 2019/07/01 00:44:29 dlg Exp $ */
+/*	$OpenBSD: ifq.c,v 1.33 2019/07/03 10:19:45 dlg Exp $ */
 
 /*
  * Copyright (c) 2015 David Gwynne <dlg@openbsd.org>
@@ -23,6 +23,7 @@
 #include <sys/socket.h>
 #include <sys/mbuf.h>
 #include <sys/proc.h>
+#include <sys/sysctl.h>
 
 #include <net/if.h>
 #include <net/if_var.h>
@@ -607,6 +608,43 @@ ifiq_process(void *arg)
 	if_input_process(ifiq->ifiq_if, &ml);
 }
 
+int
+net_ifiq_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, 
+    void *newp, size_t newlen)
+{
+	int val;
+	int error;
+
+	if (namelen != 1)
+		return (EISDIR);
+
+	switch (name[0]) {
+	case NET_LINK_IFRXQ_PRESSURE_RETURN:
+		val = ifiq_pressure_return;
+		error = sysctl_int(oldp, oldlenp, newp, newlen, &val);
+		if (error != 0)
+			return (error);
+		if (val < 1 || val > ifiq_pressure_drop)
+			return (EINVAL);
+		ifiq_pressure_return = val;
+		break;
+	case NET_LINK_IFRXQ_PRESSURE_DROP:
+		val = ifiq_pressure_drop;
+		error = sysctl_int(oldp, oldlenp, newp, newlen, &val);
+		if (error != 0)
+			return (error);
+		if (ifiq_pressure_return > val)
+			return (EINVAL);
+		ifiq_pressure_drop = val;
+		break;
+	default:
+		error = EOPNOTSUPP;
+		break;
+	}
+
+	return (error);
+}
+
 /*
  * priq implementation
  */
diff --git a/sys/sys/sysctl.h b/sys/sys/sysctl.h
index 5607ef1c8ef..836aeeb91f9 100644
--- a/sys/sys/sysctl.h
+++ b/sys/sys/sysctl.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sysctl.h,v 1.192 2019/06/25 14:08:57 deraadt Exp $	*/
+/*	$OpenBSD: sysctl.h,v 1.193 2019/07/03 10:19:45 dlg Exp $	*/
 /*	$NetBSD: sysctl.h,v 1.16 1996/04/09 20:55:36 cgd Exp $	*/
 
 /*
@@ -1031,6 +1031,7 @@ int sysctl_wdog(int *, u_int, void *, size_t *, void *, size_t);
 extern int (*cpu_cpuspeed)(int *);
 extern void (*cpu_setperf)(int);
 
+int net_ifiq_sysctl(int *, u_int, void *, size_t *, void *, size_t);
 int bpf_sysctl(int *, u_int, void *, size_t *, void *, size_t);
 int pflow_sysctl(int *, u_int, void *, size_t *, void *, size_t);
 int pipex_sysctl(int *, u_int, void *, size_t *, void *, size_t);