Author: bdrewery
Date: Thu Aug 13 22:06:27 2020
New Revision: 364220
URL: https://svnweb.freebsd.org/changeset/base/364220
Log:
lagg: Avoid adding a port to a lagg device being destroyed.
The lagg_clone_destroy() handles detach and waiting for ifconfig callers
to drain already.
This narrows the race for 2 panics that the tests triggered. Both were a
consequence of adding a port to the lagg device after it had already detached
from all of its ports. The link state task would run after
lagg_clone_destroy()
free'd the lagg softc.
kernel:trap_fatal+0xa4
kernel:trap_pfault+0x61
kernel:trap+0x316
kernel:witness_checkorder+0x6d
kernel:_sx_xlock+0x72
if_lagg.ko:lagg_port_state+0x3b
kernel:if_down+0x144
kernel:if_detach+0x659
if_tap.ko:tap_destroy+0x46
kernel:if_clone_destroyif+0x1b7
kernel:if_clone_destroy+0x8d
kernel:ifioctl+0x29c
kernel:kern_ioctl+0x2bd
kernel:sys_ioctl+0x16d
kernel:amd64_syscall+0x337
kernel:trap_fatal+0xa4
kernel:trap_pfault+0x61
kernel:trap+0x316
kernel:witness_checkorder+0x6d
kernel:_sx_xlock+0x72
if_lagg.ko:lagg_port_state+0x3b
kernel:do_link_state_change+0x9b
kernel:taskqueue_run_locked+0x10b
kernel:taskqueue_run+0x49
kernel:ithread_loop+0x19c
kernel:fork_exit+0x83
PR: 244168
Reviewed by: markj
MFC after: 2 weeks
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D25284
Modified:
head/sys/net/if_lagg.c
Modified: head/sys/net/if_lagg.c
==============================================================================
--- head/sys/net/if_lagg.c Thu Aug 13 20:48:14 2020 (r364219)
+++ head/sys/net/if_lagg.c Thu Aug 13 22:06:27 2020 (r364220)
@@ -679,6 +679,9 @@ lagg_port_create(struct lagg_softc *sc, struct ifnet *
return (EINVAL);
}
+ if (sc->sc_destroying == 1)
+ return (ENXIO);
+
/* Limit the maximal number of lagg ports */
if (sc->sc_count >= LAGG_MAX_PORTS)
return (ENOSPC);
@@ -1190,6 +1193,8 @@ lagg_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data
int count, buflen, len, error = 0, oldmtu;
bzero(&rpbuf, sizeof(rpbuf));
+
+ /* XXX: This can race with lagg_clone_destroy. */
switch (cmd) {
case SIOCGLAGG:
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