Eric Biederman pointed out that not holding RTNL while calling
call_netdevice_notifiers() was racy.

This patch is a direct transcription his feedback
against commit 0115e8e3 (net: remove delay at device dismantle)

Thanks Eric !
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Mahesh Bandewar <maheshb@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Gao feng <gaofeng@cn.fujitsu.com>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

I noticed extra one second delay in device dismantle, tracked down to
a call to dst_dev_event() while some call_rcu() are still in RCU queues.

These call_rcu() were posted by rt_free(struct rtable *rt) calls.

We then wait a little (but one second) in netdev_wait_allrefs() before
kicking again NETDEV_UNREGISTER.

As the call_rcu() are now completed, dst_dev_event() can do the needed
device swap on busy dst.

To solve this problem, add a new NETDEV_UNREGISTER_FINAL, called
after a rcu_barrier(), but outside of RTNL lock.

Use NETDEV_UNREGISTER_FINAL with care !

Change dst_dev_event() handler to react to NETDEV_UNREGISTER_FINAL

Also remove NETDEV_UNREGISTER_BATCH, as its not used anymore after
IP cache removal.

With help from Gao feng
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Mahesh Bandewar <maheshb@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Cong Wang reports that lockdep detected suspicious RCU usage while
enabling IPV6 forwarding:

 [ 1123.310275] ===============================
 [ 1123.442202] [ INFO: suspicious RCU usage. ]
 [ 1123.558207] 3.6.0-rc1+ #109 Not tainted
 [ 1123.665204] -------------------------------
 [ 1123.768254] include/linux/rcupdate.h:430 Illegal context switch in RCU read-side critical section!
 [ 1123.992320]
 [ 1123.992320] other info that might help us debug this:
 [ 1123.992320]
 [ 1124.307382]
 [ 1124.307382] rcu_scheduler_active = 1, debug_locks = 0
 [ 1124.522220] 2 locks held by sysctl/5710:
 [ 1124.648364]  #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff81768498>] rtnl_trylock+0x15/0x17
 [ 1124.882211]  #1:  (rcu_read_lock){.+.+.+}, at: [<ffffffff81871df8>] rcu_lock_acquire+0x0/0x29
 [ 1125.085209]
 [ 1125.085209] stack backtrace:
 [ 1125.332213] Pid: 5710, comm: sysctl Not tainted 3.6.0-rc1+ #109
 [ 1125.441291] Call Trace:
 [ 1125.545281]  [<ffffffff8109d915>] lockdep_rcu_suspicious+0x109/0x112
 [ 1125.667212]  [<ffffffff8107c240>] rcu_preempt_sleep_check+0x45/0x47
 [ 1125.781838]  [<ffffffff8107c260>] __might_sleep+0x1e/0x19b
[...]
 [ 1127.445223]  [<ffffffff81757ac5>] call_netdevice_notifiers+0x4a/0x4f
[...]
 [ 1127.772188]  [<ffffffff8175e125>] dev_disable_lro+0x32/0x6b
 [ 1127.885174]  [<ffffffff81872d26>] dev_forward_change+0x30/0xcb
 [ 1128.013214]  [<ffffffff818738c4>] addrconf_forward_change+0x85/0xc5
[...]

addrconf_forward_change() uses RCU iteration over the netdev list,
which is unnecessary since it already holds the RTNL lock.  We also
cannot reasonably require netdevice notifier functions not to sleep.
Reported-by: NCong Wang <amwang@redhat.com>
Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Introduce ipv6_addr_hash() helper doing a XOR on all bits
of an IPv6 address, with an optimized x86_64 version.

Use it in flow dissector, as suggested by Andrew McGregor,
to reduce hash collision probabilities in fq_codel (and other
users of flow dissector)

Use it in ip6_tunnel.c and use more bit shuffling, as suggested
by David Laight, as existing hash was ignoring most of them.

Use it in sunrpc and use more bit shuffling, using hash_32().

Use it in net/ipv6/addrconf.c, using hash_32() as well.

As a cleanup, use it in net/ipv4/tcp_metrics.c
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NAndrew McGregor <andrewmcgr@gmail.com>
Cc: Dave Taht <dave.taht@gmail.com>
Cc: Tom Herbert <therbert@google.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the current debugging style and enable dynamic_debug.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add #define pr_fmt(fmt) as appropriate.

Add "IPv6: " to appropriate files.

Convert printk(KERN_<LEVEL> to pr_<level> (but not KERN_DEBUG).
Standardize on "%s: " not "%s(): " when emitting __func__.
Use "%s: ", __func__ instead of embedding function name.
Coalesce formats, align arguments.

ADDRCONF output is now prefixed with "IPv6: "
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We are going to delete the Token ring support.  This removes any
special processing in the core networking for token ring, (aside
from net/tr.c itself), leaving the drivers and remaining tokenring
support present but inert.

The mass removal of the drivers and net/tr.c will be in a separate
commit, so that the history of these files that we still care
about won't have the giant deletion tied into their history.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

Standardize the net core ratelimited logging functions.

Coalesce formats, align arguments.
Change a printk then vprintk sequence to use printf extension %pV.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

According to the RFC4944 (Transmission of IPv6 Packets over
IEEE 802.15.4 Networks), chapter 7:

The IPv6 link-local address [RFC4291] for an IEEE 802.15.4 interface
is formed by appending the Interface Identifier, as defined above, to
the prefix FE80::/64.

  10 bits            54 bits                  64 bits
+----------+-----------------------+----------------------------+
|1111111010|         (zeros)       |    Interface Identifier    |
+----------+-----------------------+----------------------------+

This patch adds IPv6 address generation support for the 6lowpan
interfaces.
Signed-off-by: NAlexander Smirnov <alex.bluesman.smirnov@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Using an ascii path to register_net_sysctl as opposed to the slightly
awkward ctl_path allows for much simpler code.

We no longer need to malloc dev_name to keep it alive the length of our
sysctl register instead we can use a small temporary buffer on the
stack.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Acked-by: NPavel Emelyanov <xemul@parallels.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If the ipv6 dst cache which copy from the dst generated by ICMPV6 RA packet.
this dst cache will not check expire because it has no RTF_EXPIRES flag.
So this dst cache will always be used until the dst gc run.

Change the struct dst_entry,add a union contains new pointer from and expires.
When rt6_info.rt6i_flags has no RTF_EXPIRES flag,the dst.expires has no use.
we can use this field to point to where the dst cache copy from.
The dst.from is only used in IPV6.

rt6_check_expired check if rt6_info.dst.from is expired.

ip6_rt_copy only set dst.from when the ort has flag RTF_ADDRCONF
and RTF_DEFAULT.then hold the ort.

ip6_dst_destroy release the ort.

Add some functions to operate the RTF_EXPIRES flag and expires(from) together.
and change the code to use these new adding functions.

Changes from v5:
modify ip6_route_add and ndisc_router_discovery to use new adding functions.

Only set dst.from when the ort has flag RTF_ADDRCONF
and RTF_DEFAULT.then hold the ort.
Signed-off-by: NGao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c:340: WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
net/ipv6/addrconf.c:342: ERROR: "foo * bar" should be "foo *bar"
net/ipv6/addrconf.c:444: ERROR: "foo * bar" should be "foo *bar"
net/ipv6/addrconf.c:1337: WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
net/ipv6/addrconf.c:1526: ERROR: "(foo*)" should be "(foo *)"
net/ipv6/addrconf.c:1671: ERROR: open brace '{' following function declarations go on the next line
net/ipv6/addrconf.c:1914: ERROR: "foo * bar" should be "foo *bar"
net/ipv6/addrconf.c:2368: ERROR: "foo * bar" should be "foo *bar"
net/ipv6/addrconf.c:2370: ERROR: "foo * bar" should be "foo *bar"
net/ipv6/addrconf.c:2416: ERROR: "foo * bar" should be "foo *bar"
net/ipv6/addrconf.c:2437: ERROR: "foo    * bar" should be "foo    *bar"
net/ipv6/addrconf.c:2573: ERROR: "foo * bar" should be "foo *bar"
net/ipv6/addrconf.c:3797: ERROR: "foo* bar" should be "foo *bar"
Signed-off-by: NEldad Zack <eldad@fogrefinery.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

These macros contain a hidden goto, and are thus extremely error
prone and make code hard to audit.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

With commit d6ddef9e(IPv6: Fix not join all-router mcast group
when forwarding set.) I check 'dev' after it's dereference that
leads to a Smatch complaint:

net/ipv6/addrconf.c:438 ipv6_add_dev()
	 warn: variable dereferenced before check 'dev' (see line 432)

net/ipv6/addrconf.c
   431		/* protected by rtnl_lock */
   432		rcu_assign_pointer(dev->ip6_ptr, ndev);
                                   ^^^^^^^^^^^^
Old dereference.

   433
   434		/* Join all-node multicast group */
   435		ipv6_dev_mc_inc(dev, &in6addr_linklocal_allnodes);
   436
   437		/* Join all-router multicast group if forwarding is set
*/
   438		if (ndev->cnf.forwarding && dev && (dev->flags &
IFF_MULTICAST))
                                            ^^^

Remove the check to avoid the complaint as 'dev' can't be NULL.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NLi Wei <lw@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When forwarding was set and a new net device is register,
we need add this device to the all-router mcast group.
Signed-off-by: NLi Wei <lw@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There is a race condition in addrconf_sysctl_forward() and
addrconf_sysctl_disable().
These functions change idev->cnf.forwarding (resp. idev->cnf.disable_ipv6)
and then try to grab the rtnl lock before performing any actions.
If that fails they restore the original value and restart the syscall.
This creates race conditions if ipv6 code tries to access
these parameters, or if multiple instances try to do the same operation.
As an example of the former, if __ipv6_ifa_notify() finds a 0 in
idev->cnf.forwarding when invoked by addrconf_ifdown() it may not free
anycast addresses, ultimately resulting in the net_device not being freed.
This patch reads the user parameters into a temporary location and only
writes the actual parameters when the rtnl lock is acquired.
Tested in 2.6.38.8.
Signed-off-by: NFrancesco Ruggeri <fruggeri@aristanetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

commit a9b3cd7f (rcu: convert uses of rcu_assign_pointer(x, NULL) to
RCU_INIT_POINTER) did a lot of incorrect changes, since it did a
complete conversion of rcu_assign_pointer(x, y) to RCU_INIT_POINTER(x,
y).

We miss needed barriers, even on x86, when y is not NULL.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This ensures a linear behaviour when filling /proc/net/if_inet6 thus making
ifconfig run really fast on IPv6 only addresses. In fact, with this patch and
the IPv4 one sent a while ago, ifconfig will run in linear time regardless of
address type.

IPv4 related patch: f04565dd
	 dev: use name hash for dev_seq_ops
	 ...

Some statistics (running ifconfig > /dev/null on a different setup):

iface count / IPv6 no-patch time / IPv6 patched time / IPv4 time
----------------------------------------------------------------
      6250  |       0.23 s       |      0.13 s       |  0.11 s
     12500  |       0.62 s       |      0.28 s       |  0.22 s
     25000  |       2.91 s       |      0.57 s       |  0.46 s
     50000  |      11.37 s       |      1.21 s       |  0.94 s
    128000  |      86.78 s       |      3.05 s       |  2.54 s
Signed-off-by: NMihai Maruseac <mmaruseac@ixiacom.com>
Cc: Daniel Baluta <dbaluta@ixiacom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Recently Dave noticed that a test we did in ipv6_add_addr to see if we next hop
route for the interface we're adding an addres to was wrong (see commit
7ffbcecb).  for one, it never triggers, and two,
it was completely wrong to begin with.  This test was meant to cover this
section of RFC 4429:

3.3 Modifications to RFC 2462 Stateless Address Autoconfiguration

   * (modifies section 5.5) A host MAY choose to configure a new address
        as an Optimistic Address.  A host that does not know the SLLAO
        of its router SHOULD NOT configure a new address as Optimistic.
        A router SHOULD NOT configure an Optimistic Address.

This patch should bring us into proper compliance with the above clause.  Since
we only add a SLAAC address after we've received a RA which may or may not
contain a source link layer address option, we can pass a pointer to that option
to addrconf_prefix_rcv (which may be null if the option is not present), and
only set the optimistic flag if the option was found in the RA.

Change notes:
(v2) modified the new parameter to addrconf_prefix_rcv to be a bool rather than
a pointer to make its use more clear as per request from davem.
Signed-off-by: NNeil Horman <nhorman@tuxdriver.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It just obscures that the netdevice pointer and the expires value are
implemented in the dst_entry sub-object of the ipv6 route.

And it makes grepping for dst_entry member uses much harder too.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The route we have here is for the address being added to the interface,
ie. for input packet processing.

Therefore using that route to determine whether an output nexthop gateway
is known and resolved doesn't make any sense.

So, simply remove this test, it never triggered anyways.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Acked-By: NNeil Horman <nhorman@tuxdriver.com>

There is no obvious reason to add a default multicast route for loopback
devices, otherwise there would be a route entry whose dst.error set to
-ENETUNREACH that would blocking all multicast packets.

====================

[ more detailed explanation ]

The problem is that the resulting routing table depends on the sequence
of interface's initialization and in some situation, that would block all
muticast packets. Suppose there are two interfaces on my computer
(lo and eth0), if we initailize 'lo' before 'eth0', the resuting routing
table(for multicast) would be

# ip -6 route show | grep ff00::
unreachable ff00::/8 dev lo metric 256 error -101
ff00::/8 dev eth0 metric 256

When sending multicasting packets, routing subsystem will return the first
route entry which with a error set to -101(ENETUNREACH).

I know the kernel will set the default ipv6 address for 'lo' when it is up
and won't set the default multicast route for it, but there is no reason to
stop 'init' program from setting address for 'lo', and that is exactly what
systemd did.

I am sure there is something wrong with kernel or systemd, currently I preferred
kernel caused this problem.

====================
Signed-off-by: NLi Wei <lw@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

To reflect the fact that a refrence is not obtained to the
resulting neighbour entry.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NRoland Dreier <roland@purestorage.com>

C assignment can handle struct in6_addr copying.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

These files are non modular, but need to export symbols using
the macros now living in export.h -- call out the include so
that things won't break when we remove the implicit presence
of module.h from everywhere.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

The route lookup to find a previously auto-configured route for a prefixes used
to use rt6_lookup(), with the prefix from the RA used as an address. However,
that kind of lookup ignores routing tables, the prefix length and route flags,
so when there were other matching routes, even in different tables and/or with
a different prefix length, the wrong route would be manipulated.

Now, a new function "addrconf_get_prefix_route()" is used for the route lookup,
which searches in RT6_TABLE_PREFIX and takes the prefix-length and route flags
into account.
Signed-off-by: NAndreas Hofmeister <andi@collax.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When calling snmp6_alloc_dev fails, the snmp6 relevant memory
are freed by snmp6_alloc_dev. Calling in6_dev_finish_destroy
will free these memory twice.

Double free will lead that undefined behavior occurs.
Signed-off-by: NRoy Li <rongqing.li@windriver.com>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch improves the logic determining when to send ICMPv6 Router
Solicitations, so that they are 1) always sent when the kernel is
accepting Router Advertisements, and 2) never sent when the kernel is
not accepting RAs. In other words, the operational setting of the
"accept_ra" sysctl is used.

The change also makes the special "Hybrid Router" forwarding mode
("forwarding" sysctl set to 2) operate exactly the same as the standard
Router mode (forwarding=1). The only difference between the two was
that RSes was being sent in the Hybrid Router mode only. The sysctl
documentation describing the special Hybrid Router mode has therefore
been removed.

Rationale for the change:

Currently, the value of forwarding sysctl is the only thing determining
whether or not to send RSes. If it has the value 0 or 2, they are sent,
otherwise they are not. This leads to inconsistent behaviour in the
following cases:

* accept_ra=0, forwarding=0
* accept_ra=0, forwarding=2
* accept_ra=1, forwarding=2
* accept_ra=2, forwarding=1

In the first three cases, the kernel will send RSes, even though it will
not accept any RAs received in reply. In the last case, it will not send
any RSes, even though it will accept and process any RAs received. (Most
routers will send unsolicited RAs periodically, so suppressing RSes in
the last case will merely delay auto-configuration, not prevent it.)

Also, it is my opinion that having the forwarding sysctl control RS
sending behaviour (completely independent of whether RAs are being
accepted or not) is simply not what most users would intuitively expect
to be the case.
Signed-off-by: NTore Anderson <tore@fud.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Gergely Kalman reported crashes in check_peer_redir().

It appears commit f39925db (ipv4: Cache learned redirect
information in inetpeer.) added a race, leading to possible NULL ptr
dereference.

Since we can now change dst neighbour, we should make sure a reader can
safely use a neighbour.

Add RCU protection to dst neighbour, and make sure check_peer_redir()
can be called safely by different cpus in parallel.

As neighbours are already freed after one RCU grace period, this patch
should not add typical RCU penalty (cache cold effects)

Many thanks to Gergely for providing a pretty report pointing to the
bug.
Reported-by: NGergely Kalman <synapse@hippy.csoma.elte.hu>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When assigning a NULL value to an RCU protected pointer, no barrier
is needed. The rcu_assign_pointer, used to handle that but will soon
change to not handle the special case.

Convert all rcu_assign_pointer of NULL value.

//smpl
@@ expression P; @@

- rcu_assign_pointer(P, NULL)
+ RCU_INIT_POINTER(P, NULL)

// </smpl>
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Update the code to handle some of the differences between
RFC 3041 and RFC 4941, which obsoletes it. Also a couple
of janitorial fixes.

- Allow router advertisements to increase the lifetime of
  temporary addresses. This was not allowed by RFC 3041,
  but is specified by RFC 4941. It is useful when RA
  lifetimes are lower than TEMP_{VALID,PREFERRED}_LIFETIME:
  in this case, the previous code would delete or deprecate
  addresses prematurely.

- Change the default of MAX_RETRY to 3 per RFC 4941.

- Add a comment to clarify that the preferred and valid
  lifetimes in inet6_ifaddr are relative to the timestamp.

- Shorten lines to 80 characters in a couple of places.
Signed-off-by: NLorenzo Colitti <lorenzo@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Original commit 2bda8a0c... "Disable router anycast
address for /127 prefixes" says:

|   No need for matching code in addrconf_leave_anycast() as it
|   will silently ignore any attempt to leave an unknown anycast
|   address.

After analysis, because 1) we may add two or more prefixes on the
same interface, or 2)user may have manually joined that anycast,
we may hit chances to have anycast address which as if we had
generated one by /127 prefix and we should not leave from subnet-
router anycast address unconditionally.

CC: Bjørn Mork <bjorn@mork.no>
CC: Brian Haley <brian.haley@hp.com>
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

dst_{get,set}_neighbour()
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It just makes it harder to see 1) what the code is doing
and 2) grep for all users of dst{->,.}neighbour
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

RFC 6164 requires that routers MUST disable Subnet-Router anycast
for the prefix when /127 prefixes are used.

No need for matching code in addrconf_leave_anycast() as it
will silently ignore any attempt to leave an unknown anycast
address.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The message size allocated for rtnl ifinfo dumps was limited to
a single page.  This is not enough for additional interface info
available with devices that support SR-IOV and caused a bug in
which VF info would not be displayed if more than approximately
40 VFs were created per interface.

Implement a new function pointer for the rtnl_register service that will
calculate the amount of data required for the ifinfo dump and allocate
enough data to satisfy the request.
Signed-off-by: NGreg Rose <gregory.v.rose@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

Use same logic as SIT tunnel to handle link local address
for GRE tunnel. OSPFv3 requires link-local address to function.
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ipv6 has per device ICMP SNMP counters, taking too much space because
they use percpu storage.

needed size per device is :
(512+4)*sizeof(long)*number_of_possible_cpus*2

On a 32bit kernel, 16 possible cpus, this wastes more than 64kbytes of
memory per ipv6 enabled network device, taken in vmalloc pool.

Since ICMP messages are rare, just use shared counters (atomic_long_t)

Per network space ICMP counters are still using percpu memory, we might
also convert them to shared counters in a future patch.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
CC: Denys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>