Module Name: src
Committed By: ozaki-r
Date: Tue Oct 20 07:35:15 UTC 2015
Modified Files:
src/sys/net: if_llatbl.c
src/sys/netinet: if_arp.c
Log Message:
Stop using softnet_lock (fix possible deadlock)
Using softnet_lock for mutual exclusion between lltable_free and
arptimer was wrong and had an issue causing a deadlock between
them; lltable_free waits arptimer completion by calling
callout_halt with softnet_lock that is held in arptimer, however
lltable_free also holds llentry's lock that is also held in
arptimer so arptimer never obtain the lock and both never go
forward eventually. We have to pass llentry's lock to
callout_halt instead.
To generate a diff of this commit:
cvs rdiff -u -r1.6 -r1.7 src/sys/net/if_llatbl.c
cvs rdiff -u -r1.189 -r1.190 src/sys/netinet/if_arp.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/net/if_llatbl.c
diff -u src/sys/net/if_llatbl.c:1.6 src/sys/net/if_llatbl.c:1.7
--- src/sys/net/if_llatbl.c:1.6 Wed Sep 30 07:12:32 2015
+++ src/sys/net/if_llatbl.c Tue Oct 20 07:35:15 2015
@@ -1,4 +1,4 @@
-/* $NetBSD: if_llatbl.c,v 1.6 2015/09/30 07:12:32 ozaki-r Exp $ */
+/* $NetBSD: if_llatbl.c,v 1.7 2015/10/20 07:35:15 ozaki-r Exp $ */
/*
* Copyright (c) 2004 Luigi Rizzo, Alessandro Cerri. All rights reserved.
* Copyright (c) 2004-2008 Qing Li. All rights reserved.
@@ -364,7 +364,6 @@ lltable_free(struct lltable *llt)
lltable_unlink(llt);
- mutex_enter(softnet_lock);
LIST_INIT(&dchain);
IF_AFDATA_WLOCK(llt->llt_ifp);
/* Push all lles to @dchain */
@@ -373,7 +372,7 @@ lltable_free(struct lltable *llt)
IF_AFDATA_WUNLOCK(llt->llt_ifp);
LIST_FOREACH_SAFE(lle, &dchain, lle_chain, next) {
- if (callout_halt(&lle->la_timer, softnet_lock))
+ if (callout_halt(&lle->la_timer, &lle->lle_lock))
LLE_REMREF(lle);
#if defined(__NetBSD__)
/* XXX should have callback? */
@@ -394,7 +393,6 @@ lltable_free(struct lltable *llt)
#endif
llentry_free(lle);
}
- mutex_exit(softnet_lock);
llt->llt_free_tbl(llt);
}
Index: src/sys/netinet/if_arp.c
diff -u src/sys/netinet/if_arp.c:1.189 src/sys/netinet/if_arp.c:1.190
--- src/sys/netinet/if_arp.c:1.189 Wed Oct 14 11:22:55 2015
+++ src/sys/netinet/if_arp.c Tue Oct 20 07:35:15 2015
@@ -1,4 +1,4 @@
-/* $NetBSD: if_arp.c,v 1.189 2015/10/14 11:22:55 roy Exp $ */
+/* $NetBSD: if_arp.c,v 1.190 2015/10/20 07:35:15 ozaki-r Exp $ */
/*-
* Copyright (c) 1998, 2000, 2008 The NetBSD Foundation, Inc.
@@ -68,7 +68,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.189 2015/10/14 11:22:55 roy Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.190 2015/10/20 07:35:15 ozaki-r Exp $");
#ifdef _KERNEL_OPT
#include "opt_ddb.h"
@@ -317,13 +317,11 @@ arptimer(void *arg)
struct ifnet *ifp;
struct rtentry *rt;
- mutex_enter(softnet_lock);
-
if (lle == NULL)
- goto out;
+ return;
if (lle->la_flags & LLE_STATIC)
- goto out;
+ return;
LLE_WLOCK(lle);
if (callout_pending(&lle->la_timer)) {
@@ -343,7 +341,7 @@ arptimer(void *arg)
* by arpresolve() below.
*/
LLE_WUNLOCK(lle);
- goto out;
+ return;
}
ifp = lle->lle_tbl->llt_ifp;
rt = lle->la_rt;
@@ -374,9 +372,6 @@ arptimer(void *arg)
}
IF_AFDATA_UNLOCK(ifp);
-
-out:
- mutex_exit(softnet_lock);
}
/*
