From bf9ce95bd2477963bc5b1ff87d620143d3264e66 Mon Sep 17 00:00:00 2001
From: "Bjoern A. Zeeb" <bz@FreeBSD.org>
Date: Mon, 14 Feb 2011 20:49:37 +0000
Subject: [PATCH] Mfp4 CH=177256:

  Catch a set vnet upon return to user space. This usually
  means return paths with CURVNET_RESTORE() missing.

  If VNET_DEBUG is turned on we can even tell the function
  that did the CURVNET_SET() which is really helpful; else
  we print "N/A".

  Sponsored by: The FreeBSD Foundation
  Sponsored by: CK Software GmbH
  Reviewed by:  jhb

MFC after:	11 days
---
 sys/kern/subr_trap.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sys/kern/subr_trap.c b/sys/kern/subr_trap.c
index bca71f58f422..c66de3eb4a9e 100644
--- a/sys/kern/subr_trap.c
+++ b/sys/kern/subr_trap.c
@@ -74,6 +74,10 @@ __FBSDID("$FreeBSD$");
 
 #include <machine/cpu.h>
 
+#ifdef VIMAGE
+#include <net/vnet.h>
+#endif
+
 #ifdef XEN
 #include <vm/vm.h>
 #include <vm/vm_param.h>
@@ -126,6 +130,13 @@ userret(struct thread *td, struct trapframe *frame)
 	sched_userret(td);
 	KASSERT(td->td_locks == 0,
 	    ("userret: Returning with %d locks held.", td->td_locks));
+#ifdef VIMAGE
+	/* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
+	VNET_ASSERT(curvnet == NULL,
+	    ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
+	    __func__, td, p->p_pid, td->td_name, curvnet,
+	    (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
+#endif
 #ifdef XEN
 	PT_UPDATES_FLUSH();
 #endif