OS-577 race in netstack_unregister and zone creation

OS-1690 want zid2zone and zdid2zone
OS-1691 want a dcmd for going from netstack id to nestack_t
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Bryan Cantrill <bryan@joyent.com>

6 files changed, 119 insertions, 9 deletions

diff --git a/usr/src/cmd/mdb/common/modules/genunix/genunix.c b/usr/src/cmd/mdb/common/modules/genunix/genunix.c
index d68260a8f8..48578a52f4 100644
--- a/usr/src/cmd/mdb/common/modules/genunix/genunix.c
+++ b/usr/src/cmd/mdb/common/modules/genunix/genunix.c
@@ -4059,6 +4059,9 @@ static const mdb_dcmd_t dcmds[] = {
 
 	/* from netstack.c */
 	{ "netstack", "", "show stack instances", netstack },
+	{ "netstackid2netstack", ":",
+		"translate a netstack id to its netstack_t",
+		netstackid2netstack },
 
 	/* from nvpair.c */
 	{ NVPAIR_DCMD_NAME, NVPAIR_DCMD_USAGE, NVPAIR_DCMD_DESCR,
@@ -4149,6 +4152,10 @@ static const mdb_dcmd_t dcmds[] = {
 		pfiles_help },
 
 	/* from zone.c */
+	{ "zid2zone", ":", "find the zone_t with the given zone id",
+		zid2zone },
+	{ "zdid2zone", ":", "find the zone_t with the given zone debug id",
+		zdid2zone },
 	{ "zone", "?[-r [-v]]", "display kernel zone(s)", zoneprt },
 	{ "zsd", ":[-v] [zsd_key]", "display zone-specific-data entries for "
 	    "selected zones", zsd },
diff --git a/usr/src/cmd/mdb/common/modules/genunix/netstack.c b/usr/src/cmd/mdb/common/modules/genunix/netstack.c
index 588bd6dbf3..d46bd85d1f 100644
--- a/usr/src/cmd/mdb/common/modules/genunix/netstack.c
+++ b/usr/src/cmd/mdb/common/modules/genunix/netstack.c
@@ -21,10 +21,9 @@
 /*
  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
+ * Copyright (c) 2012, Joyent, Inc.  All rights reserved.
  */
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
-
 #include <mdb/mdb_modapi.h>
 #include <mdb/mdb_ks.h>
 #include <mdb/mdb_ctf.h>
@@ -121,3 +120,30 @@ netstack(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
 
 	return (DCMD_OK);
 }
+
+static int
+netstackid_lookup_cb(uintptr_t addr, const netstack_t *ns, void *arg)
+{
+	netstackid_t nid = *(uintptr_t *)arg;
+	if (ns->netstack_stackid == nid)
+		mdb_printf("%p\n", addr);
+
+	return (WALK_NEXT);
+}
+
+/*ARGSUSED*/
+int
+netstackid2netstack(uintptr_t addr, uint_t flags, int argc,
+    const mdb_arg_t *argv)
+{
+	if (!(flags & DCMD_ADDRSPEC) || argc != 0)
+		return (DCMD_USAGE);
+
+	if (mdb_walk("netstack", (mdb_walk_cb_t)netstackid_lookup_cb, &addr) ==
+	    -1) {
+		mdb_warn("failed to walk zone");
+		return (DCMD_ERR);
+	}
+
+	return (DCMD_OK);
+}
diff --git a/usr/src/cmd/mdb/common/modules/genunix/netstack.h b/usr/src/cmd/mdb/common/modules/genunix/netstack.h
index 392565caca..f5773c36c1 100644
--- a/usr/src/cmd/mdb/common/modules/genunix/netstack.h
+++ b/usr/src/cmd/mdb/common/modules/genunix/netstack.h
@@ -26,8 +26,6 @@
 #ifndef	_NETSTACK_H
 #define	_NETSTACK_H
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
-
 #include <mdb/mdb_modapi.h>
 
 #ifdef	__cplusplus
@@ -38,6 +36,7 @@ int netstack_walk_init(mdb_walk_state_t *);
 int netstack_walk_step(mdb_walk_state_t *);
 
 int netstack(uintptr_t, uint_t, int, const mdb_arg_t *);
+int netstackid2netstack(uintptr_t, uint_t, int, const mdb_arg_t *);
 
 #ifdef	__cplusplus
 }
diff --git a/usr/src/cmd/mdb/common/modules/genunix/zone.c b/usr/src/cmd/mdb/common/modules/genunix/zone.c
index 96f6b598ec..fc243061cb 100644
--- a/usr/src/cmd/mdb/common/modules/genunix/zone.c
+++ b/usr/src/cmd/mdb/common/modules/genunix/zone.c
@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, Joyent, Inc.  All rights reserved.
  */
 
 #include <mdb/mdb_param.h>
@@ -54,6 +55,56 @@ char *zone_status_names[] = {
 	"dead"			/* ZONE_IS_DEAD */
 };
 
+static int
+zid_lookup_cb(uintptr_t addr, const zone_t *zone, void *arg)
+{
+	zoneid_t zid = *(uintptr_t *)arg;
+	if (zone->zone_id == zid)
+		mdb_printf("%p\n", addr);
+
+	return (WALK_NEXT);
+}
+
+/*ARGSUSED*/
+int
+zid2zone(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	if (!(flags & DCMD_ADDRSPEC) || argc != 0)
+		return (DCMD_USAGE);
+
+	if (mdb_walk("zone", (mdb_walk_cb_t)zid_lookup_cb, &addr) == -1) {
+		mdb_warn("failed to walk zone");
+		return (DCMD_ERR);
+	}
+
+	return (DCMD_OK);
+}
+
+static int
+zdid_lookup_cb(uintptr_t addr, const zone_t *zone, void *arg)
+{
+	zoneid_t zdid = *(uintptr_t *)arg;
+	if (zone->zone_did == zdid)
+		mdb_printf("%p\n", addr);
+
+	return (WALK_NEXT);
+}
+
+/*ARGSUSED*/
+int
+zdid2zone(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	if (!(flags & DCMD_ADDRSPEC) || argc != 0)
+		return (DCMD_USAGE);
+
+	if (mdb_walk("zone", (mdb_walk_cb_t)zdid_lookup_cb, &addr) == -1) {
+		mdb_warn("failed to walk zone");
+		return (DCMD_ERR);
+	}
+
+	return (DCMD_OK);
+}
+
 int
 zoneprt(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
 {
diff --git a/usr/src/cmd/mdb/common/modules/genunix/zone.h b/usr/src/cmd/mdb/common/modules/genunix/zone.h
index e0e5038527..94a383e41c 100644
--- a/usr/src/cmd/mdb/common/modules/genunix/zone.h
+++ b/usr/src/cmd/mdb/common/modules/genunix/zone.h
@@ -27,14 +27,14 @@
 #ifndef	_ZONE_H
 #define	_ZONE_H
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
-
 #include <mdb/mdb_modapi.h>
 
 #ifdef	__cplusplus
 extern "C" {
 #endif
 
+extern int zid2zone(uintptr_t, uint_t, int argc, const mdb_arg_t *);
+extern int zdid2zone(uintptr_t, uint_t, int argc, const mdb_arg_t *);
 extern int zoneprt(uintptr_t, uint_t, int argc, const mdb_arg_t *);
 
 extern int zone_walk_init(mdb_walk_state_t *);
diff --git a/usr/src/uts/common/os/netstack.c b/usr/src/uts/common/os/netstack.c
index b8467fbe13..93fd1a387d 100644
--- a/usr/src/uts/common/os/netstack.c
+++ b/usr/src/uts/common/os/netstack.c
@@ -22,6 +22,7 @@
 /*
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
+ * Copyright (c) 2012, Joyent, Inc.  All rights reserved.
  */
 
 #include <sys/param.h>
@@ -205,6 +206,7 @@ void
 netstack_unregister(int moduleid)
 {
 	netstack_t *ns;
+	boolean_t created = B_FALSE;
 
 	ASSERT(moduleid >= 0 && moduleid < NS_MAX);
 
@@ -223,7 +225,33 @@ netstack_unregister(int moduleid)
 		nm_state_t *nms = &ns->netstack_m_state[moduleid];
 
 		mutex_enter(&ns->netstack_lock);
-		if (ns_reg[moduleid].nr_shutdown != NULL &&
+
+		/*
+		 * We need to be careful here. We could actually have a netstack
+		 * being created as we speak waiting for us to let go of this
+		 * lock to proceed. It may have set NSS_CREATE_NEEDED, but not
+		 * have gotten to the point of completing it yet. If
+		 * NSS_CREATE_NEEDED, we can safely just remove it here and
+		 * never create the module. However, if NSS_CREATE_INPROGRESS is
+		 * set, we need to still flag this module for shutdown and
+		 * deletion, just as though it had reached NSS_CREATE_COMPLETED.
+		 *
+		 * It is safe to do that because of two different guarantees
+		 * that exist in the system. The first is that before we do a
+		 * create, shutdown, or destroy, we ensure that nothing else is
+		 * in progress in the system for this netstack and wait for it
+		 * to complete. Secondly, because the zone is being created, we
+		 * know that the following call to apply_all_netstack will block
+		 * on the zone finishing its initialization.
+		 */
+		if (nms->nms_flags & NSS_CREATE_NEEDED)
+			nms->nms_flags &= ~NSS_CREATE_NEEDED;
+
+		if (nms->nms_flags & NSS_CREATE_INPROGRESS ||
+		    nms->nms_flags & NSS_CREATE_COMPLETED)
+			created = B_TRUE;
+
+		if (ns_reg[moduleid].nr_shutdown != NULL && created &&
 		    (nms->nms_flags & NSS_CREATE_COMPLETED) &&
 		    (nms->nms_flags & NSS_SHUTDOWN_ALL) == 0) {
 			nms->nms_flags |= NSS_SHUTDOWN_NEEDED;
@@ -231,8 +259,7 @@ netstack_unregister(int moduleid)
 			    netstack_t *, ns, int, moduleid);
 		}
 		if ((ns_reg[moduleid].nr_flags & NRF_REGISTERED) &&
-		    ns_reg[moduleid].nr_destroy != NULL &&
-		    (nms->nms_flags & NSS_CREATE_COMPLETED) &&
+		    ns_reg[moduleid].nr_destroy != NULL && created &&
 		    (nms->nms_flags & NSS_DESTROY_ALL) == 0) {
 			nms->nms_flags |= NSS_DESTROY_NEEDED;
 			DTRACE_PROBE2(netstack__destroy__needed,