The command
  # arp -s 62.2.0.1 a:b:c:d:e:f dev eth2
adds an entry like the following (listed by "arp -an")
  ? (62.2.0.1) at 0a:0b:0c:0d:0e:0f [ether] PERM on eth2
but the symmetric deletion command
  # arp -i eth2 -d 62.2.0.1
does not remove the PERM entry from the table, and instead leaves behind
  ? (62.2.0.1) at <incomplete> on eth2

The reason is that there is a refcnt of 1 for the arp_tbl itself
(neigh_alloc starts off the entry with a refcnt of 1), thus
the neigh_release() call from arp_invalidate() will (at best) just
decrement the ref to 1, but will never actually free it from the
table.

To fix this, we need to do something like neigh_forced_gc: if
the refcnt is 1 (i.e., on the table's ref), remove the entry from
the table and free it. This patch refactors and shares common code
between neigh_forced_gc and the newly added neigh_remove_one.

A similar issue exists for IPv6 Neighbor Cache entries, and is fixed
in a similar manner by this patch.
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Reviewed-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Using 16-bit ->hh_len doesn't save any memory, save some .text instead:

	add/remove: 0/0 grow/shrink: 1/6 up/down: 2/-19 (-17)
	function                                     old     new   delta
	neigh_update                                2312    2314      +2
	fwnet_header_cache                           199     197      -2
	eth_header_cache                             101      99      -2
	ip6_finish_output2                          2371    2368      -3
	vrf_finish_output6                          1522    1518      -4
	vrf_finish_output                           1413    1409      -4
	ip_finish_output2                           1627    1623      -4
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

neigh notifications today carry pid 0 for nlmsg_pid
in all cases. This patch fixes it to carry calling process
pid when available. Applications (eg. quagga) rely on
nlmsg_pid to ignore notifications generated by their own
netlink operations. This patch follows the routing subsystem
which already sets this correctly.
Reported-by: NVivek Venkatraman <vivek@cumulusnetworks.com>
Signed-off-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After the dst->pending_confirm flag was removed, we do not
need anymore to provide dst arg to dst_neigh_output.
So, rename it to neigh_output as before commit 5110effe
("net: Do delayed neigh confirmation.").
Signed-off-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add an explicit neighbour table overflow message (ratelimited) and
statistic to make diagnosing neighbour table overflows tractable in
the wild.

Diagnosing a neighbour table overflow can be quite difficult in the wild
because there is no explicit dmesg logged.  Callers to neighbour code
seem to use net_dbg_ratelimit when the neighbour call fails which means
the "base message" is not emitted and the callback suppressed messages
from the ratelimiting can end-up juxtaposed with unrelated messages.
Further, a forced garbage collection will increment a stat on each call
whether it was successful in freeing-up a table entry or not, so that
statistic is only a hint.  So, add a net_info_ratelimited message and
explicit statistic to the neighbour code.
Signed-off-by: NRick Jones <rick.jones2@hp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net: neighbour: Add mcast_resolicit to configure the number of multicast resolicitations in PROBE state.

We send unicast neighbor (ARP or NDP) solicitations ucast_probes
times in PROBE state.  Zhu Yanjun reported that some implementation
does not reply against them and the entry will become FAILED, which
is undesirable.

We had been dealt with such nodes by sending multicast probes mcast_
solicit times after unicast probes in PROBE state.  In 2003, I made
a change not to send them to improve compatibility with IPv6 NDP.

Let's introduce per-protocol per-interface sysctl knob "mcast_
reprobe" to configure the number of multicast (re)solicitation for
reconfirmation in PROBE state.  The default is 0, since we have
been doing so for 10+ years.
Reported-by: NZhu Yanjun <Yanjun.Zhu@windriver.com>
CC: Ulf Samuelsson <ulf.samuelsson@ericsson.com>
Signed-off-by: NYOSHIFUJI Hideaki <hideaki.yoshifuji@miraclelinux.com>
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Having to say
> #ifdef CONFIG_NET_NS
> 	struct net *net;
> #endif

in structures is a little bit wordy and a little bit error prone.

Instead it is possible to say:
> typedef struct {
> #ifdef CONFIG_NET_NS
>       struct net *net;
> #endif
> } possible_net_t;

And then in a header say:

> 	possible_net_t net;

Which is cleaner and easier to use and easier to test, as the
possible_net_t is always there no matter what the compile options.

Further this allows read_pnet and write_pnet to be functions in all
cases which is better at catching typos.

This change adds possible_net_t, updates the definitions of read_pnet
and write_pnet, updates optional struct net * variables that
write_pnet uses on to have the type possible_net_t, and finally fixes
up the b0rked users of read_pnet and write_pnet.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove a little bit of unnecessary work when transmitting a packet with
neigh_packet_xmit.  Use the neighbour table index not the address family
as a parameter.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For MPLS I am building the code so that either the neighbour mac
address can be specified or we can have a next hop in ipv4 or ipv6.

The kind of next hop we have is indicated by the neighbour table
pointer.  A neighbour table pointer of NULL is a link layer address.
A non-NULL neighbour table pointer indicates which neighbour table and
thus which address family the next hop address is in that we need to
look up.

The code either sends a packet directly or looks up the appropriate
neighbour table entry and sends the packet.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

While looking at the mpls code I found myself writing yet another
version of neigh_lookup_noref.  We currently have __ipv4_lookup_noref
and __ipv6_lookup_noref.

So to make my work a little easier and to make it a smidge easier to
verify/maintain the mpls code in the future I stopped and wrote
___neigh_lookup_noref.  Then I rewote __ipv4_lookup_noref and
__ipv6_lookup_noref in terms of this new function.  I tested my new
version by verifying that the same code is generated in
ip_finish_output2 and ip6_finish_output2 where these functions are
inlined.

To get to ___neigh_lookup_noref I added a new neighbour cache table
function key_eq.  So that the static size of the key would be
available.

I also added __neigh_lookup_noref for people who want to to lookup
a neighbour table entry quickly but don't know which neibhgour table
they are going to look up.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

- Add protocol to neigh_tbl so that dst->ops->protocol is not needed
- Acquire the device from neigh->dev

This results in a neigh_hh_init that will cache the samve values
regardless of the packets flowing through it.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The only caller is now is ax25_neigh_construct so move
neigh_compat_output into ax25_ip.c make it static and rename it
ax25_neigh_output.

Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-hams@vger.kernel.org
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After commit
d7480fd3 ("neigh: remove dynamic neigh table registration support"),
this field is not used anymore.

CC: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently there are only three neigh tables in the whole kernel:
arp table, ndisc table and decnet neigh table. What's more,
we don't support registering multiple tables per family.
Therefore we can just make these tables statically built-in.

Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In neigh_parms_release() we loop over all entries to find the entry given in
argument and being able to remove it from the list. By using a double linked
list, we can avoid this loop.

Here are some numbers with 30 000 dummy interfaces configured:

Before the patch:
$ time rmmod dummy
real	2m0.118s
user	0m0.000s
sys	1m50.048s

After the patch:
$ time rmmod dummy
real	1m9.970s
user	0m0.000s
sys	0m47.976s
Suggested-by: NThierry Herbelot <thierry.herbelot@6wind.com>
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jesper reported that br_netfilter always registers the hooks since
this is part of the bridge core. This harms performance for people that
don't need this.

This patch modularizes br_netfilter so it can be rmmod'ed, thus,
the hooks can be unregistered. I think the bridge netfilter should have
been a separated module since the beginning, Patrick agreed on that.

Note that this is breaking compatibility for users that expect that
bridge netfilter is going to be available after explicitly 'modprobe
bridge' or via automatic load through brctl.

However, the damage can be easily undone by modprobing br_netfilter.
The bridge core also spots a message to provide a clue to people that
didn't notice that this has been deprecated.

On top of that, the plan is that nftables will not rely on this software
layer, but integrate the connection tracking into the bridge layer to
enable stateful filtering and NAT, which is was bridge netfilter users
seem to require.

This patch still keeps the fake_dst_ops in the bridge core, since this
is required by when the bridge port is initialized. So we can safely
modprobe/rmmod br_netfilter anytime.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Acked-by: NFlorian Westphal <fw@strlen.de>

The code in neigh_sysctl_register() relies on a specific layout of
struct neigh_table, namely that the 'gc_*' variables are directly
following the 'parms' member in a specific order. The code, though,
expresses this in the most ugly way.

Get rid of the ugly casts and use the 'tbl' pointer to get a handle to
the table. This way we can refer to the 'gc_*' variables directly.

Similarly seen in the grsecurity patch, written by Brad Spengler.
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Brad Spengler <spender@grsecurity.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When ndo_neigh_setup is called, the bitfield used by NEIGH_VAR_SET is
not initialized yet. This might cause confusion for the people who use
NEIGH_VAR_SET in ndo_neigh_setup. So rather introduce NEIGH_VAR_INIT for
usage in ndo_neigh_setup.
Signed-off-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

RFC 4191 states in 3.5:

   When a host avoids using any non-reachable router X and instead sends
   a data packet to another router Y, and the host would have used
   router X if router X were reachable, then the host SHOULD probe each
   such router X's reachability by sending a single Neighbor
   Solicitation to that router's address.  A host MUST NOT probe a
   router's reachability in the absence of useful traffic that the host
   would have sent to the router if it were reachable.  In any case,
   these probes MUST be rate-limited to no more than one per minute per
   router.

Currently, when the neighbour corresponding to a router falls into
NUD_FAILED, it's never considered again. Introduce a new rt6_nud_state
value, RT6_NUD_FAIL_PROBE, which suggests the route should not be used but
should be probed with a single NS. The probe is ratelimited by the existing
code. To better distinguish meanings of the failure values, rename
RT6_NUD_FAIL_SOFT to RT6_NUD_FAIL_DO_RR.
Signed-off-by: NJiri Benc <jbenc@redhat.com>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Previously inet devices were only constructed when addresses are added.
Therefore the default neigh parms values they get are the ones at the
time of these operations.

Now that we're creating inet devices earlier, this changes the behaviour
of default neigh parms values in an incompatible way (see bug #8519).

This patch creates a compromise by setting the default values at the
same point as before but only for those that have not been explicitly
set by the user since the inet device's creation.

Introduced by:
commit 8030f544
Author: Herbert Xu <herbert@gondor.apana.org.au>
Date:   Thu Feb 22 01:53:47 2007 +0900

    [IPV4] devinet: Register inetdev earlier.
Signed-off-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This will be needed later on to provide better management of default values.
Signed-off-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch converts the neigh param members to an array. This allows easier
manipulation which will be needed later on to provide better management of
default values.
Signed-off-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There are a mix of function prototypes with and without extern
in the kernel sources.  Standardize on not using extern for
function prototypes.

Function prototypes don't need to be written with extern.
extern is assumed by the compiler.  Its use is as unnecessary as
using auto to declare automatic/local variables in a block.

Reflow modified prototypes to 80 columns.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

To allow both of protocol-specific data and device-specific data
attached with neighbour entry, and to eliminate size calculation
cost when allocating entry, sizeof protocol-speicic data must be
multiple of NEIGH_PRIV_ALIGN.  On 64bit archs,
sizeof(struct dn_neigh) is multiple of NEIGH_PRIV_ALIGN, but on
32bit archs, it was not.

Introduce NEIGH_ENTRY_SPACE() macro to ensure that protocol-specific
entry-size meets our requirement.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When allocating memory for neighbour cache entry, if
tbl->entry_size is not set, we always calculate
sizeof(struct neighbour) + tbl->key_len, which is common
in the same table.

With this change, set tbl->entry_size during the table
initialization phase, if it was not set, and use it in
neigh_alloc() and neighbour_priv().

This change also allow us to have both of protocol private
data and device priate data at tha same time.

Note that the only user of prototcol private is DECnet
and the only user of device private is ATM CLIP.
Since those are exclusive, we have not been facing issues
here.
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

1) Avoid dirtying neighbour's confirmed field.

  TCP workloads hits this cache line for each incoming ACK.
  Lets write n->confirmed only if there is a jiffie change.

2) Optimize neigh_hh_output() for the common Ethernet case, were
   hh_len is less than 16 bytes. Replace the memcpy() call
   by two inlined 64bit load/stores on x86_64.

Bench results using udpflood test, with -C option (MSG_CONFIRM flag
added to sendto(), to reproduce the n->confirmed dirtying on UDP)

24 threads doing 1.000.000 UDP sendto() on dummy device, 4 runs.

before : 2.247s, 2.235s, 2.247s, 2.318s
after  : 1.884s, 1.905s, 1.891s, 1.895s
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When a dst_confirm() happens, mark the confirmation as pending in the
dst.  Then on the next packet out, when we have the neigh in-hand, do
the update.

This removes the dependency in dst_confirm() of dst's having an
attached neigh.

While we're here, remove the explicit 'dst' NULL check, all except 2
or 3 call sites ensure it's not NULL.  So just fix those cases up.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Do not use the dst cached neigh, we'll be getting rid of that.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use of "unsigned int" is preferred to bare "unsigned" in net tree.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

neigh_table_init_no_netlink() is only used in net/core/neighbour.c file.
Signed-off-by: NHiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In order to perform a proper universal hash on a vector of integers,
we have to use different universal hashes on each vector element.

Which means we need 4 different hash randoms for ipv6.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This reverts commit 5c3ddec7.

S390 qeth driver actually still uses the setup ops.
Reported-by: NFrank Blaschka <blaschka@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It's simpler to just keep these things out until there is a real user
of them, so we can see what the needs actually are, rather than keep
these things around as useless overhead.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We are going to alloc for device specific private areas for
neighbour entries, and in order to do that we have to move
away from the fixed allocation size enforced by using
neigh_table->kmem_cachep

As a nice side effect we can now use kfree_rcu().
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The implementation private sits right after the primary_key memory.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Le mercredi 09 novembre 2011 à 16:21 -0500, David Miller a écrit :
> From: David Miller <davem@davemloft.net>
> Date: Wed, 09 Nov 2011 16:16:44 -0500 (EST)
>
> > From: Eric Dumazet <eric.dumazet@gmail.com>
> > Date: Wed, 09 Nov 2011 12:14:09 +0100
> >
> >> unres_qlen is the number of frames we are able to queue per unresolved
> >> neighbour. Its default value (3) was never changed and is responsible
> >> for strange drops, especially if IP fragments are used, or multiple
> >> sessions start in parallel. Even a single tcp flow can hit this limit.
> >  ...
> >
> > Ok, I've applied this, let's see what happens :-)
>
> Early answer, build fails.
>
> Please test build this patch with DECNET enabled and resubmit.  The
> decnet neigh layer still refers to the removed ->queue_len member.
>
> Thanks.

Ouch, this was fixed on one machine yesterday, but not the other one I
used this morning, sorry.

[PATCH V5 net-next] neigh: new unresolved queue limits

unres_qlen is the number of frames we are able to queue per unresolved
neighbour. Its default value (3) was never changed and is responsible
for strange drops, especially if IP fragments are used, or multiple
sessions start in parallel. Even a single tcp flow can hit this limit.

$ arp -d 192.168.20.108 ; ping -c 2 -s 8000 192.168.20.108
PING 192.168.20.108 (192.168.20.108) 8000(8028) bytes of data.
8008 bytes from 192.168.20.108: icmp_seq=2 ttl=64 time=0.322 ms
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: NArun Sharma <asharma@fb.com>
Reviewed-by: NEric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This will get us closer to being able to do "neigh stuff"
completely independent of the underlying dst_entry for
protocols (ipv4/ipv6) that wish to do so.

We will also be able to make dst entries neigh-less.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It is always dev_queue_xmit().
Signed-off-by: NDavid S. Miller <davem@davemloft.net>