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, 17 insertions, 0 deletions

diff --git a/sys/kern/uipc_syscalls.c b/sys/kern/uipc_syscalls.c
index 662b3abd..5689aeb 100644
--- a/sys/kern/uipc_syscalls.c
+++ b/sys/kern/uipc_syscalls.c
@@ -64,6 +64,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sysctl.h>
 #include <sys/uio.h>
 #include <sys/vnode.h>
+#include <sys/vimage.h>
 #ifdef KTRACE
 #include <sys/ktrace.h>
 #endif
@@ -264,7 +265,9 @@ listen(td, uap)
 		if (error)
 			goto done;
 #endif
+		CURVNET_SET(so->so_vnet);
 		error = solisten(so, uap->backlog, td);
+		CURVNET_RESTORE();
 #ifdef MAC
 done:
 #endif
@@ -429,7 +432,9 @@ kern_accept(struct thread *td, int s, struct sockaddr **name,
 	tmp = fflag & FASYNC;
 	(void) fo_ioctl(nfp, FIOASYNC, &tmp, td->td_ucred, td);
 	sa = 0;
+	CURVNET_SET(so->so_vnet);
 	error = soaccept(so, &sa);
+	CURVNET_RESTORE();
 	if (error) {
 		/*
 		 * return a namelen of zero for older code which might
@@ -976,9 +981,11 @@ kern_recvit(td, s, mp, fromseg, controlp)
 		ktruio = cloneuio(&auio);
 #endif
 	len = auio.uio_resid;
+	CURVNET_SET(so->so_vnet);
 	error = soreceive(so, &fromsa, &auio, (struct mbuf **)0,
 	    (mp->msg_control || controlp) ? &control : (struct mbuf **)0,
 	    &mp->msg_flags);
+	CURVNET_RESTORE();
 	if (error) {
 		if (auio.uio_resid != (int)len && (error == ERESTART ||
 		    error == EINTR || error == EWOULDBLOCK))
@@ -1322,7 +1329,9 @@ kern_setsockopt(td, s, level, name, val, valseg, valsize)
 	error = getsock(td->td_proc->p_fd, s, &fp, NULL);
 	if (error == 0) {
 		so = fp->f_data;
+		CURVNET_SET(so->so_vnet);
 		error = sosetopt(so, &sopt);
+		CURVNET_RESTORE();
 		fdrop(fp, td);
 	}
 	return(error);
@@ -1400,7 +1409,9 @@ kern_getsockopt(td, s, level, name, val, valseg, valsize)
 	error = getsock(td->td_proc->p_fd, s, &fp, NULL);
 	if (error == 0) {
 		so = fp->f_data;
+		CURVNET_SET(so->so_vnet);
 		error = sogetopt(so, &sopt);
+		CURVNET_RESTORE();
 		*valsize = sopt.sopt_valsize;
 		fdrop(fp, td);
 	}
@@ -1463,7 +1474,9 @@ kern_getsockname(struct thread *td, int fd, struct sockaddr **sa,
 		return (error);
 	so = fp->f_data;
 	*sa = NULL;
+	CURVNET_SET(so->so_vnet);
 	error = (*so->so_proto->pr_usrreqs->pru_sockaddr)(so, sa);
+	CURVNET_RESTORE();
 	if (error)
 		goto bad;
 	if (*sa == NULL)
@@ -1564,7 +1577,9 @@ kern_getpeername(struct thread *td, int fd, struct sockaddr **sa,
 		goto done;
 	}
 	*sa = NULL;
+	CURVNET_SET(so->so_vnet);
 	error = (*so->so_proto->pr_usrreqs->pru_peeraddr)(so, sa);
+	CURVNET_RESTORE();
 	if (error)
 		goto bad;
 	if (*sa == NULL)
@@ -2176,9 +2191,11 @@ retry_space:
 				goto done;
 			}
 			SOCKBUF_UNLOCK(&so->so_snd);
+			CURVNET_SET(so->so_vnet);
 			/* Avoid error aliasing. */
 			err = (*so->so_proto->pr_usrreqs->pru_send)
 				    (so, 0, m, NULL, NULL, td);
+			CURVNET_RESTORE();
 			if (err == 0) {
 				/*
 				 * We need two counters to get the