Module Name:    src
Committed By:   jdolecek
Date:           Tue May 12 10:02:56 UTC 2020

Modified Files:
        src/sys/kern: kern_pmf.c

Log Message:
need to take IFNET_LOCK() around if_stop (on suspend) and if_init (on resume)
calls, those need to read and/or manipulate if_flags and hence need
the lock for IFEF_MPSAFE drivers; the drivers can't do IFNET_LOCK() themselves,
because the ioctl path call these hooks with the lock held

fixes KASSERT() in xennet(4) while investigating PR port-xen/55207


To generate a diff of this commit:
cvs rdiff -u -r1.42 -r1.43 src/sys/kern/kern_pmf.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

Modified files:

Index: src/sys/kern/kern_pmf.c
diff -u src/sys/kern/kern_pmf.c:1.42 src/sys/kern/kern_pmf.c:1.43
--- src/sys/kern/kern_pmf.c:1.42	Mon Apr 20 21:39:05 2020
+++ src/sys/kern/kern_pmf.c	Tue May 12 10:02:56 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_pmf.c,v 1.42 2020/04/20 21:39:05 ad Exp $ */
+/* $NetBSD: kern_pmf.c,v 1.43 2020/05/12 10:02:56 jdolecek Exp $ */
 
 /*-
  * Copyright (c) 2007 Jared D. McNeill <jmcne...@invisible.ca>
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_pmf.c,v 1.42 2020/04/20 21:39:05 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_pmf.c,v 1.43 2020/05/12 10:02:56 jdolecek Exp $");
 
 #include <sys/types.h>
 #include <sys/param.h>
@@ -893,7 +893,9 @@ pmf_class_network_suspend(device_t dev, 
 	int s;
 
 	s = splnet();
+	IFNET_LOCK(ifp);
 	(*ifp->if_stop)(ifp, 0);
+	IFNET_UNLOCK(ifp);
 	splx(s);
 
 	return true;
@@ -904,14 +906,21 @@ pmf_class_network_resume(device_t dev, c
 {
 	struct ifnet *ifp = device_pmf_class_private(dev);
 	int s;
+	bool restart = false;
 
 	s = splnet();
+	IFNET_LOCK(ifp);
 	if (ifp->if_flags & IFF_UP) {
 		ifp->if_flags &= ~IFF_RUNNING;
 		if ((*ifp->if_init)(ifp) != 0)
 			aprint_normal_ifnet(ifp, "resume failed\n");
-		if_start_lock(ifp);
+		restart = true;
 	}
+	IFNET_UNLOCK(ifp);
+
+	if (restart)
+		if_start_lock(ifp);
+
 	splx(s);
 
 	return true;

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