Date: Sat, 20 Nov 2010 23:22:50 +0200 From: Mikolaj Golub <to.my.trociny@gmail.com> To: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> Cc: freebsd-hackers@freebsd.org Subject: Re: flowtable_cleaner/flowtable_flush livelock Message-ID: <864obbofkl.fsf@kopusha.home.net> In-Reply-To: <20101120200208.M24596@maildrop.int.zabbadoz.net> (Bjoern A. Zeeb's message of "Sat, 20 Nov 2010 20:04:35 %2B0000 (UTC)") References: <86pqu0nexd.fsf@kopusha.home.net> <20101120165604.T24596@maildrop.int.zabbadoz.net> <868w0nolqo.fsf@kopusha.home.net> <20101120200208.M24596@maildrop.int.zabbadoz.net>
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On Sat, 20 Nov 2010 20:04:35 +0000 (UTC) Bjoern A. Zeeb wrote:
BAZ> How do you reproduce the crash? Is it just another ifioctl race as
BAZ> from kern/146250?
Using the same script I posted in my first mail, removing a jail and epair
interface simultaneously:
ifconfig epair0b vnet myjail
jail -r myjail &
ifconfig epair0a destroy
For me it loooks like other thread is destroying interface improperly in that
time. One time I saw crash in another thread:
(kgdb) bt
#0 doadump () at pcpu.h:231
#1 0xc04f2439 in db_fncall (dummy1=1, dummy2=0, dummy3=-1056689728, dummy4=0xc2ba5984 "")
at /usr/src/sys/ddb/db_command.c:548
#2 0xc04f2831 in db_command (last_cmdp=0xc0e75cfc, cmd_table=0x0, dopager=1)
at /usr/src/sys/ddb/db_command.c:445
#3 0xc04f298a in db_command_loop () at /usr/src/sys/ddb/db_command.c:498
#4 0xc04f48ad in db_trap (type=12, code=0) at /usr/src/sys/ddb/db_main.c:229
#5 0xc090face in kdb_trap (type=12, code=0, tf=0xc2ba5bf8) at /usr/src/sys/kern/subr_kdb.c:546
#6 0xc0c3d2bf in trap_fatal (frame=0xc2ba5bf8, eva=3735929066)
at /usr/src/sys/i386/i386/trap.c:971
#7 0xc0c3d4f0 in trap_pfault (frame=0xc2ba5bf8, usermode=0, eva=3735929066)
at /usr/src/sys/i386/i386/trap.c:893
#8 0xc0c3dca5 in trap (frame=0xc2ba5bf8) at /usr/src/sys/i386/i386/trap.c:568
#9 0xc0c24a9c in calltrap () at /usr/src/sys/i386/i386/exception.s:168
#10 0xc09ad219 in vnet_destroy (vnet=0xc2f24240) at /usr/src/sys/net/vnet.c:284
#11 0xc08b5922 in prison_deref (pr=0xc3640800, flags=Variable "flags" is not available.
) at /usr/src/sys/kern/kern_jail.c:2506
#12 0xc08b5ab0 in prison_complete (context=0xc3640800, pending=1)
at /usr/src/sys/kern/kern_jail.c:2433
#13 0xc091c87b in taskqueue_run_locked (queue=0xc2dd6d80)
at /usr/src/sys/kern/subr_taskqueue.c:247
#14 0xc091cf17 in taskqueue_thread_loop (arg=0xc0ebb8e8)
at /usr/src/sys/kern/subr_taskqueue.c:379
#15 0xc08af558 in fork_exit (callout=0xc091ceb0 <taskqueue_thread_loop>, arg=0xc0ebb8e8,
frame=0xc2ba5d28) at /usr/src/sys/kern/kern_fork.c:835
#16 0xc0c24b44 in fork_trampoline () at /usr/src/sys/i386/i386/exception.s:275
(kgdb) fr 10
#10 0xc09ad219 in vnet_destroy (vnet=0xc2f24240) at /usr/src/sys/net/vnet.c:284
284 TAILQ_FOREACH_SAFE(ifp, &V_ifnet, if_link, nifp) {
(kgdb) list
279 VNET_LIST_WUNLOCK();
280
281 CURVNET_SET_QUIET(vnet);
282
283 /* Return all inherited interfaces to their parent vnets. */
284 TAILQ_FOREACH_SAFE(ifp, &V_ifnet, if_link, nifp) {
285 if (ifp->if_home_vnet != ifp->if_vnet)
286 if_vmove(ifp, ifp->if_home_vnet);
287 }
288
(kgdb) p ifp
$1 = (struct ifnet *) 0xdeadc0de
Doesn't this need some lock protection? I tried the attached patch, but still
observed crashes in ifioctl I posted earlier.
--
Mikolaj Golub
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Content-Type: text/x-patch
Content-Disposition: attachment; filename=vnet.c.patch
Index: sys/net/vnet.c
===================================================================
--- sys/net/vnet.c (revision 215576)
+++ sys/net/vnet.c (working copy)
@@ -268,7 +268,7 @@ vnet_alloc(void)
void
vnet_destroy(struct vnet *vnet)
{
- struct ifnet *ifp, *nifp;
+ struct ifnet *ifp;
SDT_PROBE2(vnet, functions, vnet_destroy, entry, __LINE__, vnet);
KASSERT(vnet->vnet_sockcnt == 0,
@@ -281,10 +281,20 @@ vnet_destroy(struct vnet *vnet)
CURVNET_SET_QUIET(vnet);
/* Return all inherited interfaces to their parent vnets. */
- TAILQ_FOREACH_SAFE(ifp, &V_ifnet, if_link, nifp) {
- if (ifp->if_home_vnet != ifp->if_vnet)
+ do {
+ IFNET_RLOCK();
+ TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
+ if (ifp->if_home_vnet != ifp->if_vnet) {
+ if_ref(ifp);
+ break;
+ }
+ }
+ IFNET_RUNLOCK();
+ if (ifp != NULL) {
if_vmove(ifp, ifp->if_home_vnet);
- }
+ if_rele(ifp);
+ }
+ } while (ifp != NULL);
vnet_sysuninit();
CURVNET_RESTORE();
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