Initially function was introduced in r53541 (KAME initial commit) to
"provide hints from upper layer protocols that indicate a connection
is making "forward progress"" (quote from RFC 2461 7.3.1 Reachability
Confirmation).
However, it was converted to do nothing (e.g. just return) in r122922
(tcp_hostcache implementation) back in 2003. Some defines were moved
to tcp_var.h in r169541. Then, it was broken (for non-corner cases)
by r186119 (L2<>L3 split) in 2008 (NULL ifp in nd6_lookup). So,
right now this code is broken and has no "real" base users.
Differential Revision: https://reviews.freebsd.org/D3699
without holding afdata wlock
* convert per-af delete_address callback to global lltable_delete_entry() and
more low-level "delete this lle" per-af callback
* fix some bugs/inconsistencies in IPv4/IPv6 ifscrub procedures
Sponsored by: Yandex LLC
Differential Revision: https://reviews.freebsd.org/D3573
Before that, the logic besides lle_create() was the following:
return existing if found, create if not. This behaviour was error-prone
since we had to deal with 'sudden' static<>dynamic lle changes.
This commit fixes bunch of different issues like:
- refcount leak when lle is converted to static.
Simple check case:
console 1:
while true;
do for i in `arp -an|awk '$4~/incomp/{print$2}'|tr -d '()'`;
do arp -s $i 00:22:44:66:88:00 ; arp -d $i;
done;
done
console 2:
ping -f any-dead-host-in-L2
console 3:
# watch for memory consumption:
vmstat -m | awk '$1~/lltable/{print$2}'
- possible problems in arptimer() / nd6_timer() when dropping/reacquiring
lock.
New logic explicitly handles use-or-create cases in every lla_create
user. Basically, most of the changes are purely mechanical. However,
we explicitly avoid using existing lle's for interface/static LLE records.
* While here, call lle_event handlers on all real table lle change.
* Create lltable_free_entry() calling existing per-lltable
lle_free_t callback for entry deletion
* Split lltable_init() into lltable_allocate_htbl() (alloc
hash table with default callbacks) and lltable_link() (
links any lltable to the list).
* Switch from LLTBL_HASHTBL_SIZE to per-lltable hash size field.
* Move lltable setup to separate functions in in[6]_domifattach.
differences between projects/routing and HEAD.
This commit tries to keep code logic the same while changing underlying
code to use unified callbacks.
* Add llt_foreach_entry method to traverse all entries in given llt
* Add llt_dump_entry method to export particular lle entry in sysctl/rtsock
format (code is not indented properly to minimize diff). Will be fixed
in the next commits.
* Add llt_link_entry/llt_unlink_entry methods to link/unlink particular lle.
* Add llt_fill_sa_entry method to export address in the lle to sockaddr
format.
* Add llt_hash method to use in generic hash table support code.
* Add llt_free_entry method which is used in llt_prefix_free code.
* Prepare for fine-grained locking by separating lle unlink and deletion in
lltable_free() and lltable_prefix_free().
* Provide lltable_get<ifp|af>() functions to reduce direct 'struct lltable'
access by external callers.
* Remove @llt agrument from lle_free() lle callback since it was unused.
* Temporarily add L3_CADDR() macro for 'const' sockaddr typecasting.
* Switch to per-af hashing code.
* Rename LLE_FREE_LOCKED() callback from in[6]_lltable_free() to
in_[6]lltable_destroy() to avoid clashing with llt_free_entry() method.
Update description from these functions.
* Use unified lltable_free_entry() function instead of per-af one.
Reviewed by: ae
* Make most of lltable_* methods 'normal' functions instead of inline
* Add lltable_get_<af|ifp>() functions to access given lltable fields
* Temporarily resurrect nd6_lookup() function
and explicit calls to RTENTRY_FREE_LOCKED()
* Use lltable_prefix_free() in arp_ifscrub to be consistent with nd6.
* Rename <lltable_|llt>_delete function to _delete_addr() to note that
this function is used to external callers. Make this function maintain
its own locking.
* Use lookup/unlink/clear call chain from internal callers instead of
delete_addr.
* Fix LLE_DELETED flag handling
cleanup including unlinking/freeing
* Relax locking in lltable_prefix_free_af/lltable_free
* Do not pass @llt to lle free callback: it is always NULL now.
* Unify arptimer/nd6_llinfo_timer: explicitly unlock lle avoiding
unlock/lock sequinces
* Do not pass unlocked lle to nd6_ns_output(): add nd6_llinfo_get_holdsrc()
to retrieve preferred source address from lle hold queue and pass it
instead of lle.
* Finally, make nd6_create() create and return unlocked lle
* Separate defrtr handling code from nd6_free():
use nd6_check_del_defrtr() to check if we need to keep entry instead of
performing GC,
use nd6_check_recalc_defrtr() to perform actual recalc on lle removal.
* Move isRouter handling from nd6_cache_lladdr() to separate
nd6_check_router()
* Add initial code to maintain lle runtime flags in sync.
* struct llentry is now basically split into 2 pieces:
all fields within 64 bytes (amd64) are now protected by both
ifdata lock AND lle lock, e.g. you require both locks to be held
exclusively for modification. All data necessary for fast path
operations is kept here. Some fields were added:
- r_l3addr - makes lookup key liev within first 64 bytes.
- r_flags - flags, containing pre-compiled decision whether given
lle contains usable data or not. Current the only flag is RLLE_VALID.
- r_len - prepend data len, currently unused
- r_kick - used to provide feedback to control plane (see below).
All other fields are protected by lle lock.
* Add simple state machine for ARP to handle "about to expire" case:
Current model (for the fast path) is the following:
- rlock afdata
- find / rlock rte
- runlock afdata
- see if "expire time" is approaching
(time_uptime + la->la_preempt > la->la_expire)
- if true, call arprequest() and decrease la_preempt
- store MAC and runlock rte
New model (data plane):
- rlock afdata
- find rte
- check if it can be used using r_* fields only
- if true, store MAC
- if r_kick field != 0 set it to 0.
- runlock afdata
New mode (control plane):
- schedule arptimer to be called in (V_arpt_keep - V_arp_maxtries)
seconds instead of V_arpt_keep.
- on first timer invocation change state from ARP_LLINFO_REACHABLE
to ARP_LLINFO_VERIFY, sets r_kick to 1 and shedules next call in
V_arpt_rexmit (default to 1 sec).
- on subsequent timer invocations in ARP_LLINFO_VERIFY state, checks
for r_kick value: reschedule if not changed, and send arprequest()
if set to zero (e.g. entry was used).
* Convert IPv4 path to use new single-lock approach. IPv6 bits to follow.
* Slow down in_arpinput(): now valid reply will (in most cases) require
acquiring afdata WLOCK twice. This is requirement for storing changed
lle data. This change will be slightly optimized in future.
* Provide explicit hash link/unlink functions for both ipv4/ipv6 code.
This will probably be moved to generic lle code once we have per-AF
hashing callback inside lltable.
* Perform lle unlink on deletion immediately instead of delaying it to
the timer routine.
* Make r244183 more explicit: use new LLE_CALLOUTREF flag to indicate the
presence of lle reference used for safe callout calls.
lla_lookup(LLE_CREATE) -> lla_create
lla_lookup(LLE_DELETE) -> lla_delete
Assume lla_create to return LLE_EXCLUSIVE lock for lle.
* Rework lla_rt_output to perform all lle changes under afdata WLOCK.
* change arp_ifscrub() ackquire afdata WLOCK, the same as arp_ifinit().
reside on their own cache line to prevent false sharing with other
nearby structures, especially for those in the .bss segment.
NB: Those mutexes and rwlocks with variables next to them that get
changed on every invocation do not benefit from their own cache line.
Actually it may be net negative because two cache misses would be
incurred in those cases.
Since ARP and routing are separated, "proxy only" entries
don't have any meaning, thus we don't need additional field
in sockaddr to pass SIN_PROXY flag.
New kernel is binary compatible with old tools, since sizes
of sockaddr_inarp and sockaddr_in match, and sa_family are
filled with same value.
The structure declaration is left for compatibility with
third party software, but in tree code no longer use it.
Reviewed by: ru, andre, net@
entering llentry_free(), and in case if we lose the race, we should simply
perform LLE_FREE_LOCKED(). Otherwise, if the race is lost by the thread
performing arptimer(), it will remove two references from the lle instead
of one.
Reported by: Ian FREISLICH <ianf clue.co.za>
llentry_free() and arptimer():
o Use callout_init_rw() for lle timeout, this allows us safely
disestablish them.
- This allows us to simplify the arptimer() and make it
race safe.
o Consistently use ifp->if_afdata_lock to lock access to
linked lists in the lle hashes.
o Introduce new lle flag LLE_LINKED, which marks an entry that
is attached to the hash.
- Use LLE_LINKED to avoid double unlinking via consequent
calls to llentry_free().
- Mark lle with LLE_DELETED via |= operation istead of =,
so that other flags won't be lost.
o Make LLE_ADDREF(), LLE_REMREF() and LLE_FREE_LOCKED() more
consistent and provide more informative KASSERTs.
The patch is a collaborative work of all submitters and myself.
PR: kern/165863
Submitted by: Andrey Zonov <andrey zonov.org>
Submitted by: Ryan Stone <rysto32 gmail.com>
Submitted by: Eric van Gyzen <eric_van_gyzen dell.com>
referenced within its timeout window. This change clears the LLE_VALID flag when an llentry
is removed from an interface's hash table and adds an extra check to the flowtable code
for the LLE_VALID flag in llentry to avoid retaining and using a stale reference.
Reviewed by: qingli@
MFC after: 2 weeks
interface is brought down, even though the interface address is still
valid. This patch maintains the permanent ARP entries as long as the
interface address (having the same prefix as that of the ARP entries)
is valid.
Reviewed by: delphij
MFC after: 5 days
DPCPU_DEFINE and VNET_DEFINE macros, as these cause problems for various
people working on the affected files. A better long-term solution is
still being considered. This reversal may give some modules empty
set_pcpu or set_vnet sections, but these are harmless.
Changes reverted:
------------------------------------------------------------------------
r215318 | dim | 2010-11-14 21:40:55 +0100 (Sun, 14 Nov 2010) | 4 lines
Instead of unconditionally emitting .globl's for the __start_set_xxx and
__stop_set_xxx symbols, only emit them when the set_vnet or set_pcpu
sections are actually defined.
------------------------------------------------------------------------
r215317 | dim | 2010-11-14 21:38:11 +0100 (Sun, 14 Nov 2010) | 3 lines
Apply the STATIC_VNET_DEFINE and STATIC_DPCPU_DEFINE macros throughout
the tree.
------------------------------------------------------------------------
r215316 | dim | 2010-11-14 21:23:02 +0100 (Sun, 14 Nov 2010) | 2 lines
Add macros to define static instances of VNET_DEFINE and DPCPU_DEFINE.
When a fast machine first brings up some non TCP networking program
it is quite possible that we will drop packets due to the fact that
only one packet can be held per ARP entry. This leads to packets
being missed when a program starts or restarts if the ARP data is
not currently in the ARP cache.
This code adds a new sysctl, net.link.ether.inet.maxhold, which defines
a system wide maximum number of packets to be held in each ARP entry.
Up to maxhold packets are queued until an ARP reply is received or
the ARP times out. The default setting is the old value of 1
which has been part of the BSD networking code since time
immemorial.
Expose the time we hold an incomplete ARP entry by adding
the sysctl net.link.ether.inet.wait, which defaults to 20
seconds, the value used when the new ARP code was added..
Reviewed by: bz, rpaulo
MFC after: 3 weeks
either find an existing entry, or allocate a new one. In the latter
case an entry would have flags, that were supplied as argument to
lla_lookup(). In case of an existing entry, flags aren't modified.
This lead to losing LLE_PUB and/or LLE_PROXY flags.
We should apply these flags either in lla_rt_output() or in the
in.c:in_lltable_lookup(). It seems to me that lla_rt_output() is
a more correct choice.
PR: kern/148784, kern/146539
Silence from: qingli, 5 days
prevented the link-layer entry from being freed.
In both in.c and in6.c (though that code path seems to be basically dead)
plug a reference leak in case of a pending callout being drained.
In if_ether.c consistently add a reference before resetting the callout
and in case we canceled a pending one remove the reference for that.
In the final case in arptimer, before freeing the expired entry, remove
the reference again and explicitly call callout_stop() to clear the active
flag.
In nd6.c:nd6_free() we are only ever called from the callout function and
thus need to remove the reference there as well before calling into
llentry_free().
In if_llatbl.c when freeing entire tables make sure that in case we cancel
a pending callout to remove the reference as well.
Reviewed by: qingli (earlier version)
MFC after: 10 days
Problem observed, patch tested by: simon on ipv6gw.f.o,
Christian Kratzer (ck cksoft.de),
Evgenii Davidov (dado korolev-net.ru)
PR: kern/144564
Configurations still affected: with options FLOWTABLE
- show all lltables [1] (optional flag to also show the llentries as well)
- show lltable <struct lltable *>
- show llentry <struct llentry *>
MFC after: 6 days
- add a name argument to flowtable_alloc for printing with ddb commands
- extend ddb commands to print destination address or 4-tuples
- don't parse ports in ulp header if FL_HASH_ALL is not passed
- add kern_flowtable_insert to enable more generic use of flowtable
(e.g. system calls for adding entries)
- don't hash loopback addresses
- cleanup whitespace
- keep statistics per-cpu for per-cpu flowtables to avoid cache line contention
- add sysctls to accumulate stats and report aggregate
MFC after: 7 days
IFF_POINTOPOINT link types. The reason was due to the routing
entry returned from the kernel covering the remote end is of an
interface type that does not support ARP. This patch fixes this
problem by providing a hint to the kernel routing code, which
indicates the prefix route instead of the PPP host route should
be returned to the caller. Since a host route to the local end
point is also added into the routing table, and there could be
multiple such instantiations due to multiple PPP links can be
created with the same local end IP address, this patch also fixes
the loopback route installation failure problem observed prior to
this patch. The reference count of loopback route to local end would
be either incremented or decremented. The first instantiation would
create the entry and the last removal would delete the route entry.
MFC after: 5 days
usable again with options VIMAGE kernels.
Submitted by: bz (the original version, probably identical to this one)
Reviewed by: many @ DevSummit Cambridge
MFC after: 3 days
