svn commit: r339358 - head/sys/net
Hans Petter Selasky
hselasky at FreeBSD.org
Mon Oct 15 10:29:31 UTC 2018
Author: hselasky
Date: Mon Oct 15 10:29:29 2018
New Revision: 339358
URL: https://svnweb.freebsd.org/changeset/base/339358
Log:
Fix deadlock when destroying VLANs.
Synchronizing the epoch before freeing the multicast addresses while holding
the VLAN_XLOCK() might lead to a deadlock. Use deferred freeing of the VLAN
multicast addresses to resolve deadlock. Backtrace:
Thread1:
epoch_block_handler_preempt()
ck_epoch_synchronize_wait()
epoch_wait_preempt()
vlan_setmulti()
vlan_ioctl()
in6m_release_task()
gtaskqueue_run_locked()
gtaskqueue_thread_loop()
fork_exit()
fork_trampoline()
Thread2:
sleepq_switch()
sleepq_wait()
_sx_xlock_hard()
_sx_xlock()
in6_leavegroup()
in6_purgeaddr()
if_purgeaddrs()
if_detach_internal()
if_detach()
vlan_clone_destroy()
if_clone_destroyif()
if_clone_destroy()
ifioctl()
kern_ioctl()
sys_ioctl()
amd64_syscall()
fast_syscall_common()
syscall()
Differential revision: https://reviews.freebsd.org/D17496
Reviewed by: slavash, mmacy
Approved by: re (kib)
Sponsored by: Mellanox Technologies
Modified:
head/sys/net/if_vlan.c
Modified: head/sys/net/if_vlan.c
==============================================================================
--- head/sys/net/if_vlan.c Mon Oct 15 10:25:34 2018 (r339357)
+++ head/sys/net/if_vlan.c Mon Oct 15 10:29:29 2018 (r339358)
@@ -153,6 +153,7 @@ struct ifvlantrunk {
struct vlan_mc_entry {
struct sockaddr_dl mc_addr;
CK_SLIST_ENTRY(vlan_mc_entry) mc_entries;
+ struct epoch_context mc_epoch_ctx;
};
struct ifvlan {
@@ -317,6 +318,13 @@ VNET_DEFINE_STATIC(struct if_clone *, vlan_cloner);
#define HASH(n, m) ((((n) >> 8) ^ ((n) >> 4) ^ (n)) & (m))
static void
+vlan_mc_free(struct epoch_context *ctx)
+{
+ struct vlan_mc_entry *mc = __containerof(ctx, struct vlan_mc_entry, mc_epoch_ctx);
+ free(mc, M_VLAN);
+}
+
+static void
vlan_inithash(struct ifvlantrunk *trunk)
{
int i, n;
@@ -572,8 +580,7 @@ vlan_setmulti(struct ifnet *ifp)
while ((mc = CK_SLIST_FIRST(&sc->vlan_mc_listhead)) != NULL) {
CK_SLIST_REMOVE_HEAD(&sc->vlan_mc_listhead, mc_entries);
(void)if_delmulti(ifp_p, (struct sockaddr *)&mc->mc_addr);
- NET_EPOCH_WAIT();
- free(mc, M_VLAN);
+ epoch_call(net_epoch_preempt, &mc->mc_epoch_ctx, vlan_mc_free);
}
/* Now program new ones. */
@@ -1485,8 +1492,7 @@ vlan_unconfig_locked(struct ifnet *ifp, int departing)
error);
}
CK_SLIST_REMOVE_HEAD(&ifv->vlan_mc_listhead, mc_entries);
- NET_EPOCH_WAIT();
- free(mc, M_VLAN);
+ epoch_call(net_epoch_preempt, &mc->mc_epoch_ctx, vlan_mc_free);
}
vlan_setflags(ifp, 0); /* clear special flags on parent */
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