[src/trunk]: src/sys/net ifnet(9): Kernel lock for struct ifnet::if_timer.

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

details:   https://anonhg.NetBSD.org/src/rev/209c5b0c350a
branches:  trunk
changeset: 369495:209c5b0c350a
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat Aug 20 12:42:51 2022 +0000

description:
ifnet(9): Kernel lock for struct ifnet::if_timer.

diffstat:

 sys/net/if.c |  20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

diffs (48 lines):

diff -r 5b0e254b0cd6 -r 209c5b0c350a sys/net/if.c
--- a/sys/net/if.c      Sat Aug 20 12:30:00 2022 +0000
+++ b/sys/net/if.c      Sat Aug 20 12:42:51 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if.c,v 1.514 2022/08/20 11:09:41 riastradh Exp $       */
+/*     $NetBSD: if.c,v 1.515 2022/08/20 12:42:51 riastradh 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 1.514 2022/08/20 11:09:41 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if.c,v 1.515 2022/08/20 12:42:51 riastradh Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_inet.h"
@@ -2686,6 +2686,19 @@
  * from softclock, we decrement timer (if set) and
  * call the appropriate interface routine on expiration.
  */
+static bool
+if_slowtimo_countdown(struct ifnet *ifp)
+{
+       bool fire = false;
+
+       KERNEL_LOCK(1, NULL); /* for ifp->ifp_timer */
+       if (ifp->if_timer != 0 && --ifp->if_timer == 0)
+               fire = true;
+       KERNEL_UNLOCK_ONE(NULL);
+
+       return fire;
+}
+
 static void
 if_slowtimo_intr(void *arg)
 {
@@ -2694,8 +2707,7 @@
 
        mutex_enter(&isd->isd_lock);
        if (!isd->isd_dying) {
-               if (isd->isd_trigger ||
-                   (ifp->if_timer != 0 && --ifp->if_timer == 0)) {
+               if (isd->isd_trigger || if_slowtimo_countdown(ifp)) {
                        if (!isd->isd_queued) {
                                isd->isd_queued = true;
                                workqueue_enqueue(if_slowtimo_wq,