[src/trunk]: src/sys/net f_detach(): Drain the protocol input queues before t...

[thorpej <thorpej%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/4aefdce63a63
branches:  trunk
changeset: 369811:4aefdce63a63
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Fri Sep 02 04:34:58 2022 +0000

description:
f_detach(): Drain the protocol input queues before the pr_purgeif()
calls; pktq_barrier() doesn't remove packets from the queue, it waits
for the packets enqueued before the barrier to drain.  This, in turn,
may cause the protocols to gain additional references to the interface
that's detaching.  By draining the queues first, we ensure that no
additional references will be taken after calling pr_purgeif().

diffstat:

 sys/net/if.c |  58 +++++++++++++++++++++++++++++-----------------------------
 1 files changed, 29 insertions(+), 29 deletions(-)

diffs (86 lines):

diff -r d171961c6643 -r 4aefdce63a63 sys/net/if.c
--- a/sys/net/if.c      Fri Sep 02 03:50:00 2022 +0000
+++ b/sys/net/if.c      Fri Sep 02 04:34:58 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if.c,v 1.521 2022/09/02 03:50:00 thorpej Exp $ */
+/*     $NetBSD: if.c,v 1.522 2022/09/02 04:34:58 thorpej Exp $ */
 
 /*-
  * Copyright (c) 1999, 2000, 2001, 2008 The NetBSD Foundation, Inc.
@@ -90,7 +90,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if.c,v 1.521 2022/09/02 03:50:00 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if.c,v 1.522 2022/09/02 04:34:58 thorpej Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_inet.h"
@@ -1399,6 +1399,33 @@
 #endif
 
        /*
+        * remove packets that came from ifp, from software interrupt queues.
+        */
+       DOMAIN_FOREACH(dp) {
+               for (i = 0; i < __arraycount(dp->dom_ifqueues); i++) {
+                       struct ifqueue *iq = dp->dom_ifqueues[i];
+                       if (iq == NULL)
+                               break;
+                       dp->dom_ifqueues[i] = NULL;
+                       if_detach_queues(ifp, iq);
+               }
+       }
+
+       /*
+        * IP queues have to be processed separately: net-queue barrier
+        * ensures that the packets are dequeued while a cross-call will
+        * ensure that the interrupts have completed. FIXME: not quite..
+        */
+#ifdef INET
+       pktq_barrier(ip_pktq);
+#endif
+#ifdef INET6
+       if (in6_present)
+               pktq_barrier(ip6_pktq);
+#endif
+       xc_barrier(0);
+
+       /*
         * Rip all the addresses off the interface.  This should make
         * all of the routes go away.
         *
@@ -1518,33 +1545,6 @@
 
        IF_AFDATA_LOCK_DESTROY(ifp);
 
-       /*
-        * remove packets that came from ifp, from software interrupt queues.
-        */
-       DOMAIN_FOREACH(dp) {
-               for (i = 0; i < __arraycount(dp->dom_ifqueues); i++) {
-                       struct ifqueue *iq = dp->dom_ifqueues[i];
-                       if (iq == NULL)
-                               break;
-                       dp->dom_ifqueues[i] = NULL;
-                       if_detach_queues(ifp, iq);
-               }
-       }
-
-       /*
-        * IP queues have to be processed separately: net-queue barrier
-        * ensures that the packets are dequeued while a cross-call will
-        * ensure that the interrupts have completed. FIXME: not quite..
-        */
-#ifdef INET
-       pktq_barrier(ip_pktq);
-#endif
-#ifdef INET6
-       if (in6_present)
-               pktq_barrier(ip6_pktq);
-#endif
-       xc_barrier(0);
-
        if (ifp->if_percpuq != NULL) {
                if_percpuq_destroy(ifp->if_percpuq);
                ifp->if_percpuq = NULL;