From: kn <kn@openbsd.org>
Date: Fri, 21 Oct 2022 14:20:03 +0000 (+0000)
Subject: Grab the non-exclusive net lock to read-only traverse the interface list
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=7e119dafdd61b2a9d6ea84db9e635de73872d169;p=openbsd

Grab the non-exclusive net lock to read-only traverse the interface list

Destroying lo(4) interfaces checks for other interfaces in the same
rdomain(4) first which does not modify anything, so allow other readers.

All interface ioctl(2)s currently run with the kernel lock held, so this
should not make a real difference...

OK mvs
---

diff --git a/sys/net/if_loop.c b/sys/net/if_loop.c
index a15820420ef..4077198b637 100644
--- a/sys/net/if_loop.c
+++ b/sys/net/if_loop.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_loop.c,v 1.92 2022/09/08 10:22:06 kn Exp $	*/
+/*	$OpenBSD: if_loop.c,v 1.93 2022/10/21 14:20:03 kn Exp $	*/
 /*	$NetBSD: if_loop.c,v 1.15 1996/05/07 02:40:33 thorpej Exp $	*/
 
 /*
@@ -204,16 +204,16 @@ loop_clone_destroy(struct ifnet *ifp)
 			return (EPERM);
 
 		/* if there is any other interface in this rdomain, deny */
-		NET_LOCK();
+		NET_LOCK_SHARED();
 		TAILQ_FOREACH(p, &ifnetlist, if_list) {
 			if (p->if_rdomain != ifp->if_rdomain)
 				continue;
 			if (p->if_index == ifp->if_index)
 				continue;
-			NET_UNLOCK();
+			NET_UNLOCK_SHARED();
 			return (EBUSY);
 		}
-		NET_UNLOCK();
+		NET_UNLOCK_SHARED();
 
 		rdomain = ifp->if_rdomain;
 	}