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
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=339358
@ -153,6 +153,7 @@ struct ifvlantrunk {
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struct vlan_mc_entry {
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struct sockaddr_dl mc_addr;
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CK_SLIST_ENTRY(vlan_mc_entry) mc_entries;
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struct epoch_context mc_epoch_ctx;
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};
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struct ifvlan {
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@ -316,6 +317,13 @@ VNET_DEFINE_STATIC(struct if_clone *, vlan_cloner);
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#ifndef VLAN_ARRAY
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#define HASH(n, m) ((((n) >> 8) ^ ((n) >> 4) ^ (n)) & (m))
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static void
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vlan_mc_free(struct epoch_context *ctx)
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{
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struct vlan_mc_entry *mc = __containerof(ctx, struct vlan_mc_entry, mc_epoch_ctx);
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free(mc, M_VLAN);
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}
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static void
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vlan_inithash(struct ifvlantrunk *trunk)
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{
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@ -572,8 +580,7 @@ vlan_setmulti(struct ifnet *ifp)
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while ((mc = CK_SLIST_FIRST(&sc->vlan_mc_listhead)) != NULL) {
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CK_SLIST_REMOVE_HEAD(&sc->vlan_mc_listhead, mc_entries);
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(void)if_delmulti(ifp_p, (struct sockaddr *)&mc->mc_addr);
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NET_EPOCH_WAIT();
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free(mc, M_VLAN);
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epoch_call(net_epoch_preempt, &mc->mc_epoch_ctx, vlan_mc_free);
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}
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/* Now program new ones. */
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@ -1485,8 +1492,7 @@ vlan_unconfig_locked(struct ifnet *ifp, int departing)
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error);
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}
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CK_SLIST_REMOVE_HEAD(&ifv->vlan_mc_listhead, mc_entries);
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NET_EPOCH_WAIT();
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free(mc, M_VLAN);
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epoch_call(net_epoch_preempt, &mc->mc_epoch_ctx, vlan_mc_free);
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}
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vlan_setflags(ifp, 0); /* clear special flags on parent */
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