Change the curvnet variable from a global const struct vnet *,

previously always pointing to the default vnet context, to a
dynamically changing thread-local one.  The currvnet context
should be set on entry to networking code via CURVNET_SET() macros,
and reverted to previous state via CURVNET_RESTORE().  Recursions
on curvnet are permitted, though strongly discuouraged.

This change should have no functional impact on nooptions VIMAGE
kernel builds, where CURVNET_* macros expand to whitespace.

The curthread->td_vnet (aka curvnet) variable's purpose is to be an
indicator of the vnet context in which the current network-related
operation takes place, in case we cannot deduce the current vnet
context from any other source, such as by looking at mbuf's
m->m_pkthdr.rcvif->if_vnet, sockets's so->so_vnet etc.  Moreover, so
far curvnet has turned out to be an invaluable consistency checking
aid: it helps to catch cases when sockets, ifnets or any other
vnet-aware structures may have leaked from one vnet to another.

The exact placement of the CURVNET_SET() / CURVNET_RESTORE() macros
was a result of an empirical iterative process, whith an aim to
reduce recursions on CURVNET_SET() to a minimum, while still reducing
the scope of CURVNET_SET() to networking only operations - the
alternative would be calling CURVNET_SET() on each system call entry.
In general, curvnet has to be set in three typicall cases: when
processing socket-related requests from userspace or from within the
kernel; when processing inbound traffic flowing from device drivers
to upper layers of the networking stack, and when executing
timer-driven networking functions.

This change also introduces a DDB subcommand to show the list of all
vnet instances.

Approved by:	julian (mentor)

1 files changed, 5 insertions, 1 deletions

diff --git a/sys/netinet6/ip6_mroute.c b/sys/netinet6/ip6_mroute.c
index a88a9a1..5a76ef3 100644
--- a/sys/netinet6/ip6_mroute.c
+++ b/sys/netinet6/ip6_mroute.c
@@ -219,7 +219,7 @@ static struct mtx mif6_mtx;
 
 #ifdef MRT6DEBUG
 #ifdef VIMAGE_GLOBALS
-static u_int mrt6debug = 0;		/* debug level */
+static u_int mrt6debug;		/* debug level */
 #endif
 #define DEBUG_MFC	0x02
 #define DEBUG_FORWARD	0x04
@@ -546,7 +546,11 @@ ip6_mrouter_init(struct socket *so, int v, int cmd)
 {
 	INIT_VNET_INET6(curvnet);
 
+	V_ip6_mrouter_ver = 0;
+
 #ifdef MRT6DEBUG
+	V_mrt6debug = 0;
+
 	if (V_mrt6debug)
 		log(LOG_DEBUG,
 		    "ip6_mrouter_init: so_type = %d, pr_protocol = %d\n",