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, 6 insertions, 6 deletions

diff --git a/sys/net/if_clone.c b/sys/net/if_clone.c
index 8ffb758..a0140fc 100644
--- a/sys/net/if_clone.c
+++ b/sys/net/if_clone.c
@@ -39,6 +39,7 @@
 #include <sys/systm.h>
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <sys/vimage.h>
 
 #include <net/if.h>
 #include <net/if_clone.h>
@@ -49,6 +50,7 @@
 #include <net/if_var.h>
 #include <net/radix.h>
 #include <net/route.h>
+#include <net/vnet.h>
 
 static void	if_clone_free(struct if_clone *ifc);
 static int	if_clone_createif(struct if_clone *ifc, char *name, size_t len,
@@ -203,15 +205,14 @@ if_clone_destroyif(struct if_clone *ifc, struct ifnet *ifp)
 {
 	int err;
 
-	if (ifc->ifc_destroy == NULL) {
-		err = EOPNOTSUPP;
-		goto done;
-	}
+	if (ifc->ifc_destroy == NULL)
+		return(EOPNOTSUPP);
 
 	IF_CLONE_LOCK(ifc);
 	IFC_IFLIST_REMOVE(ifc, ifp);
 	IF_CLONE_UNLOCK(ifc);
 
+	CURVNET_SET_QUIET(ifp->if_vnet);
 	if_delgroup(ifp, ifc->ifc_name);
 
 	err =  (*ifc->ifc_destroy)(ifc, ifp);
@@ -223,8 +224,7 @@ if_clone_destroyif(struct if_clone *ifc, struct ifnet *ifp)
 		IFC_IFLIST_INSERT(ifc, ifp);
 		IF_CLONE_UNLOCK(ifc);
 	}
-
-done:
+	CURVNET_RESTORE();
 	return (err);
 }