For unknown reasons, IPv6 multicast addresses are linked to a first
IPv6 address assigned to an interface. Due to the design, when removing
a first address having multicast addresses, we need to save them to
somewhere and later restore them once a new IPv6 address is activated.
mkludge stuffs support the operations.
This change links multicast addresses to an interface directly and
throws the kludge away.
Note that as usual some obsolete member variables remain for kvm(3)
users. And also sysctl net.inet6.multicast_kludge remains to avoid
breaking old ifmcstat.
TODO: currently ifnet has a list of in6_multi but obviously the list
should be protocol independent. Provide a common structure (if_multi
or something) to handle in6_multi and in_multi together as well as
ifaddr does for in_ifaddr and in6_ifaddr.
We cannot remove a prefix there. Instead just invalidate it; the prefix
will be removed when purging an associated address. This is the same as
the original behavior.
The benefits of this change are:
- The flow is consistent with IPv4 (and FreeBSD and OpenBSD)
- old: ip6_output => nd6_output (do ND if needed) => L2_output (lookup a stored cache)
- new: ip6_output => L2_output (lookup a cache. Do ND if cache not found)
- We can remove some workarounds in nd6_output
- We can move L2 specific operations to their own place
- The performance slightly improves because one cache lookup is reduced
pr_input is currently called in softint. Some pr_input such as ICMP, ICMPv6
and CARP can add/delete/update IP addresses and routing table entries. For
example, icmp6_redirect_input updates an a routing table entry and
nd6_ra_input may delete an IP address.
Basically such operations shouldn't be done in softint. That aside, we have
a reason to avoid the situation; psz/psref waits cannot be used in softint,
however they are required to work in such pr_input in the MP-safe world.
The change implements the workqueue pr_input framework called wqinput which
provides a means to defer pr_input of a protocol to workqueue easily.
Currently icmp_input, icmp6_input, carp_proto_input and carp6_proto_input
are deferred to workqueue by the framework.
Proposed and discussed on tech-kern and tech-net
- Don't hold softnet_lock in some functions if NET_MPSAFE
- Add softnet_lock to sysctl_net_inet_icmp_redirtimeout
- Add softnet_lock to expire_upcalls of ip_mroute.c
- Restore softnet_lock for in{,6}_pcbpurgeif{,0} if NET_MPSAFE
- Mark some softnet_lock for future work
It's useless in this case, because without it we can know that
the lock is held or not on a next lock acquisition and even more
if LOCKDEBUG is enabled a failure on the acquisition will provide
useful information for debugging while an assertion failure will
provide just the fact that the assertion failed.
llentry timer (of nd6) holds both llentry's lock and softnet_lock.
A caller also holds them and calls callout_halt to wait for the
timer to quit. However we can pass only one lock to callout_halt,
so passing either of them can cause a deadlock. Fix it by avoid
calling callout_halt without holding llentry's lock.
BTW in the first place we cannot pass llentry's lock to callout_halt
because it's a rwlock...
