From d3be1471c71fdfb310846f91308f29f40eb8ce2f Mon Sep 17 00:00:00 2001
From: Sam Leffler <sam@FreeBSD.org>
Date: Wed, 5 Nov 2003 23:42:51 +0000
Subject: [PATCH] o make debug_mpsafenet globally visible o move it from
 subr_bus.c to netisr.c where it more properly belongs o add NET_PICKUP_GIANT
 and NET_DROP_GIANT macros that will be used to   grab Giant as needed when
 MPSAFE operation is enabled

Supported by:	FreeBSD Foundation
---
 sys/kern/subr_bus.c | 10 ----------
 sys/net/netisr.c    | 10 ++++++++++
 sys/sys/mutex.h     | 21 +++++++++++++++++++++
 3 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c
index 347489fe379..092f410d4d0 100644
--- a/sys/kern/subr_bus.c
+++ b/sys/kern/subr_bus.c
@@ -2133,16 +2133,6 @@ bus_release_resource(device_t dev, int type, int rid, struct resource *r)
 	return (BUS_RELEASE_RESOURCE(dev->parent, dev, type, rid, r));
 }
 
-/*
- * XXX this is a temporary measure to allow folks to
- * XXX disable INTR_MPSAFE in network drivers without
- * XXX recompiling--in case of problems.
- */
-int	debug_mpsafenet = 0;
-TUNABLE_INT("debug.mpsafenet", &debug_mpsafenet);
-SYSCTL_INT(_debug, OID_AUTO, mpsafenet, CTLFLAG_RW, &debug_mpsafenet, 0,
-    "Enable/disable MPSAFE network support");
-
 int
 bus_setup_intr(device_t dev, struct resource *r, int flags,
     driver_intr_t handler, void *arg, void **cookiep)
diff --git a/sys/net/netisr.c b/sys/net/netisr.c
index 347fd9a0c94..cb24e12fb73 100644
--- a/sys/net/netisr.c
+++ b/sys/net/netisr.c
@@ -53,6 +53,16 @@
 #include <net/if_var.h>
 #include <net/netisr.h>
 
+/*
+ * XXX this is a temporary measure to allow folks to
+ * XXX disable Giant locking in the network code without
+ * XXX recompiling--in case of problems.
+ */
+int	debug_mpsafenet = 0;
+TUNABLE_INT("debug.mpsafenet", &debug_mpsafenet);
+SYSCTL_INT(_debug, OID_AUTO, mpsafenet, CTLFLAG_RD, &debug_mpsafenet, 0,
+    "Enable/disable MPSAFE network support");
+
 volatile unsigned int	netisr;	/* scheduling bits for network */
 
 struct netisr {
diff --git a/sys/sys/mutex.h b/sys/sys/mutex.h
index 9601fd7f755..05575b5e61b 100644
--- a/sys/sys/mutex.h
+++ b/sys/sys/mutex.h
@@ -339,6 +339,27 @@ do {									\
 		WITNESS_RESTORE(&Giant.mtx_object, Giant)
 #endif
 
+/*
+ * Network MPSAFE temporary workarounds.  When debug_mpsafenet
+ * is 1 the network is assumed to operate without Giant on the
+ * input path and protocols that require Giant must collect it
+ * on entry.  When 0 Giant is grabbed in the network interface
+ * ISR's and in the netisr path and there is no need to grab
+ * the Giant lock.
+ *
+ * This mechanism is intended as temporary until everything of
+ * importance is properly locked.
+ */
+extern	int debug_mpsafenet;		/* defined in net/netisr.c */
+#define	NET_PICKUP_GIANT() do {						\
+	if (debug_mpsafenet)						\
+		mtx_lock(&Giant);					\
+} while (0)
+#define	NET_DROP_GIANT() do {						\
+	if (debug_mpsafenet)						\
+		mtx_unlock(&Giant);					\
+} while (0)
+
 #define	UGAR(rval) do {							\
 	int _val = (rval);						\
 	mtx_unlock(&Giant);						\