Added clearing of SW resource bits in the SW/FW synchronization
register to ixgbe_init_swfw_sync_X540().

Updated ixgbe_acquire_swfw_sync_X540 SW Manageability host interface
resource bit error case to match the error handling of the other SW
resource bits. Which is to release the SW resource bits if SW times
out while attempting to acquire the resource.

This allows the driver to load in cases where the semaphore bits
could be stuck after a reset or a crash.
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

dcb_app priority is unsigned thus checking whether it is less than zero
is redundant.
Signed-off-by: Christos Gkekas <chris.gekas@gmail.com>
Acked-By: Tomer Tayar <Tomer.Tayar@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Many macros in dwmac-ipq806x are unused and should be removed.
Moreover gmac->id is an unsigned variable and therefore checking
whether it is less than zero is redundant.
Signed-off-by: Christos Gkekas <chris.gekas@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Eric Dumazet says:

====================
ipv6: ipv6_dev_get_saddr() rcu works

Sending IPv6 udp packets on non connected sockets is quite slow,
because ipv6_dev_get_saddr() is still using an rwlock and silly
references games on ifa.

Tested:

$ ./super_netperf 16 -H 4444::555:0786 -l 2000 -t UDP_STREAM -- -m 100 &
[1] 12527

Performance is boosted from 2.02 Mpps to 4.28 Mpps

Kernel profile before patches :
  22.62%  [kernel]  [k] _raw_read_lock_bh
   7.04%  [kernel]  [k] refcount_sub_and_test
   6.56%  [kernel]  [k] ipv6_get_saddr_eval
   5.67%  [kernel]  [k] _raw_read_unlock_bh
   5.34%  [kernel]  [k] __ipv6_dev_get_saddr
   4.95%  [kernel]  [k] refcount_inc_not_zero
   4.03%  [kernel]  [k] __ip6addrlbl_match
   3.70%  [kernel]  [k] _raw_spin_lock
   3.44%  [kernel]  [k] ipv6_dev_get_saddr
   3.24%  [kernel]  [k] ip6_pol_route
   3.06%  [kernel]  [k] refcount_add_not_zero
   2.30%  [kernel]  [k] __local_bh_enable_ip
   1.81%  [kernel]  [k] mlx4_en_xmit
   1.20%  [kernel]  [k] __ip6_append_data
   1.12%  [kernel]  [k] __ip6_make_skb
   1.11%  [kernel]  [k] __dev_queue_xmit
   1.06%  [kernel]  [k] l3mdev_master_ifindex_rcu

Kernel profile after patches :
  11.36%  [kernel]  [k] ip6_pol_route
   7.65%  [kernel]  [k] _raw_spin_lock
   7.16%  [kernel]  [k] __ipv6_dev_get_saddr
   6.49%  [kernel]  [k] ipv6_get_saddr_eval
   6.04%  [kernel]  [k] refcount_add_not_zero
   3.34%  [kernel]  [k] __ip6addrlbl_match
   2.62%  [kernel]  [k] __dev_queue_xmit
   2.37%  [kernel]  [k] mlx4_en_xmit
   2.26%  [kernel]  [k] dst_release
   1.89%  [kernel]  [k] __ip6_make_skb
   1.87%  [kernel]  [k] __ip6_append_data
   1.86%  [kernel]  [k] udpv6_sendmsg
   1.86%  [kernel]  [k] ip6t_do_table
   1.64%  [kernel]  [k] ipv6_dev_get_saddr
   1.64%  [kernel]  [k] find_match
   1.51%  [kernel]  [k] l3mdev_master_ifindex_rcu
   1.24%  [kernel]  [k] ipv6_addr_label
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

By extending the rcu section a bit, we can avoid these
very expensive in6_ifa_put()/in6_ifa_hold() calls
done in __ipv6_dev_get_saddr() and ipv6_dev_get_saddr()
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Callers hold rcu_read_lock(), so we do not need
the rcu_read_lock()/rcu_read_unlock() pair.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

inet6_ifa_finish_destroy() already uses kfree_rcu() to free
inet6_ifaddr structs.

We need to use proper list additions/deletions in order
to allow readers to use RCU instead of idev->lock rwlock.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Roopa Prabhu says:

====================
bridge: neigh msg proxy and flood suppression support

This series implements arp and nd suppression in the bridge
driver for ethernet vpns. It implements rfc7432, section 10
https://tools.ietf.org/html/rfc7432#section-10
for ethernet VPN deployments. It is similar to the existing
BR_PROXYARP* flags but has a few semantic differences to conform
to EVPN standard. Unlike the existing flags, this new flag suppresses
flood of all neigh discovery packets (arp and nd) to tunnel ports.
Supports both vlan filtering and non-vlan filtering bridges.

In case of EVPN, it is mainly used to avoid flooding
of arp and nd packets to tunnel ports like vxlan.

v2 : rebase to latest + address some optimization feedback from Nikolay.
v3 : fix kbuild reported build errors with CONFIG_INET off
v4 : simplify port flag mask as suggested by stephen
v5 : address some feedback from Toshiaki
v6 : some v5 cleanups in nd suppress (keep it consistent with arp suppress)
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch avoids flooding and proxies ndisc packets
for BR_NEIGH_SUPPRESS ports.
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch avoids flooding and proxies arp packets
for BR_NEIGH_SUPPRESS ports.

Moves existing br_do_proxy_arp to br_do_proxy_suppress_arp
to support both proxy arp and neigh suppress.
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch adds a new bridge port flag BR_NEIGH_SUPPRESS to
suppress arp and nd flood on bridge ports. It implements
rfc7432, section 10.
https://tools.ietf.org/html/rfc7432#section-10
for ethernet VPN deployments. It is similar to the existing
BR_PROXYARP* flags but has a few semantic differences to conform
to EVPN standard. Unlike the existing flags, this new flag suppresses
flood of all neigh discovery packets (arp and nd) to tunnel ports.
Supports both vlan filtering and non-vlan filtering bridges.

In case of EVPN, it is mainly used to avoid flooding
of arp and nd packets to tunnel ports like vxlan.

This patch adds netlink and sysfs support to set this bridge port
flag.
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Ido reported following splat and provided a patch.

[  122.221814] BUG: using smp_processor_id() in preemptible [00000000] code: sshd/2672
[  122.221845] caller is debug_smp_processor_id+0x17/0x20
[  122.221866] CPU: 0 PID: 2672 Comm: sshd Not tainted 4.14.0-rc3-idosch-next-custom #639
[  122.221880] Hardware name: Mellanox Technologies Ltd. MSN2100-CB2FO/SA001017, BIOS 5.6.5 06/07/2016
[  122.221893] Call Trace:
[  122.221919]  dump_stack+0xb1/0x10c
[  122.221946]  ? _atomic_dec_and_lock+0x124/0x124
[  122.221974]  ? ___ratelimit+0xfe/0x240
[  122.222020]  check_preemption_disabled+0x173/0x1b0
[  122.222060]  debug_smp_processor_id+0x17/0x20
[  122.222083]  ip6_pol_route+0x1482/0x24a0
...

I believe we can simplify this code path a bit, since we no longer
hold a read_lock and need to release it to avoid a dead lock.

By disabling BH, we make sure we'll prevent code re-entry and
rt6_get_pcpu_route()/rt6_make_pcpu_route() run on the same cpu.

Fixes: 66f5d6ce ("ipv6: replace rwlock with rcu and spinlock in fib6_table")
Reported-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Saeed Mahameed says:

====================
Mellanox, mlx5 updates 2017-10-06

This series includes some shared code updates for kernel 4.15 to both
net-next and rdma-next trees.

The series includes mlx5 low level flow steering updates and optimizations
to support firmware command parallelism for flow steering requests from
Maor Gottlieb and two other small fixes from Matan and Maor.

One fix from Matan adds error handling for when the destination
list of the flow steering rule is full.

Maor introduced a patch to avoid NULL pointer dereference on steering cleanup.

Then Some refactoring patches needed by the series for code sharing purposes.
and split the Flow Table Entry (FTE) and Flow Group (FG) creation code to two parts:
    1) Object allocation - allocate the steering node and initialize
    its resources.

    2) The firmware command execution.

This change will give us the ability to take write lock on the
parent node (e.g. FG for FTE creating) only on the software data struct allocation
and creation part of the procedure where the synchronization is really required,
and will allow us to execute multiple firmware commands simultaneously and overcome the
firmware bottleneck.

Refactor the locking scheme of the mlx5 core flow steering as follows:

1) Replace the mutex lock with readers-writers semaphore and take
    the write lock only when necessary (e.g. allocating a new flow
    table entry index or adding a node to the parent's children list).
    When we try to find a suitable child in the parent's children list
    (e.g. search for flow group with the same match_criteria of the rule)
    then we only take the read lock.

2) Add versioning mechanism - each steering entity (FT, FG, FTE, DST)
    will have an incremental version. The version is increased when the
    entity is changed (e.g. when a new FTE was added to FG - the FG's
    version is increased).
    Versioning is used in order to determine if the last traverse of an
    entity's children is valid or a rescan under write lock is required.

Last patch adds FGs and FTEs memory pool, It is useful because these objects
are not small and could be allocated/deallocated many times.

This support improves the insertion rate of steering rules
from ~5k/sec to ~40k/sec.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Haiyang Zhang says:

====================
hv_netvsc: support changing TCP hash level

The patch set simplifies the existing hash level switching code for
UDP. It also adds the support for changing TCP hash level. So users
can switch between L3 an L4 hash levels for TCP and UDP.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Update Documentation/networking/netvsc.txt for TCP hash level setting
and related info.
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The patch supports the options to switch TCP hash level between
L3 and L4 by ethtool command. TCP over IPv4 and v6 can be set
differently. The default hash level is L4. We currently only
allow switching TX hash level from within the guests.

For example, for TCP over IPv4 on eth0:
To include TCP port numbers in hashing:
	ethtool -N eth0 rx-flow-hash tcp4 sdfn
To exclude TCP port numbers in hashing:
	ethtool -N eth0 rx-flow-hash tcp4 sd
To show TCP hash level:
	ethtool -n eth0 rx-flow-hash tcp4
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This simplifies the logic and make it easier to add more
options.
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Jiri Pirko says:

====================
mlxsw: Add more extack error reporting

Ido says:

Add error messages to VLAN and bridge enslavements to help users
understand why the enslavement failed.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The code that actually takes care of bridge offload introduces a few
more non-trivial constraints with regards to bridge enslavements.
Propagate extack there to indicate the reason.

$ ip link add link enp1s0np1 name enp1s0np1.10 type vlan id 10
$ ip link add link enp1s0np1 name enp1s0np1.20 type vlan id 20
$ ip link add name br0 type bridge
$ ip link set dev enp1s0np1.10 master br0
$ ip link set dev enp1s0np1.20 master br0
Error: spectrum: Can not bridge VLAN uppers of the same port.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Similar to physical ports, enslavement of VLAN devices can also fail.
Use extack to indicate why the enslavement failed.

$ ip link add link enp1s0np1 name enp1s0np1.10 type vlan id 10
$ ip link add name bond0 type bond mode 802.3ad
$ ip link set dev enp1s0np1.10 master bond0
Error: spectrum: VLAN devices only support bridge and VRF uppers.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Martin KaFai Lau says:

====================
bpf: Misc improvements and a new usage on bpf obj name

The first two patches make improvements on the bpf obj name.

The last patch adds the prog name to kallsyms.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch makes the bpf_prog's name available
in kallsyms.

The new format is bpf_prog_tag[_name].

Sample kallsyms from running selftests/bpf/test_progs:
[root@arch-fb-vm1 ~]# egrep ' bpf_prog_[0-9a-fA-F]{16}' /proc/kallsyms
ffffffffa0048000 t bpf_prog_dabf0207d1992486_test_obj_id
ffffffffa0038000 t bpf_prog_a04f5eef06a7f555__123456789ABCDE
ffffffffa0050000 t bpf_prog_a04f5eef06a7f555
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Instead of u8, use char for prog and map name.  It can avoid the
userspace tool getting compiler's signess warning.  The
bpf_prog_aux, bpf_map, bpf_attr, bpf_prog_info and
bpf_map_info are changed.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

During get_info_by_fd, the prog/map name is memcpy-ed.  It depends
on the prog->aux->name and map->name to be zero initialized.

bpf_prog_aux is easy to guarantee that aux->name is zero init.

The name in bpf_map may be harder to be guaranteed in the future when
new map type is added.

Hence, this patch makes bpf_obj_name_cpy() to always zero init
the prog/map name.
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

Similarly to early patch for erspan_xmit(), the ARPHDR_ETHER device
is the length of the whole ether packet.  So skb->len should subtract
the dev->hard_header_len.

Fixes: 1a66a836 ("gre: add collect_md mode to ERSPAN tunnel")
Fixes: 84e54fe0 ("gre: introduce native tunnel support for ERSPAN")
Signed-off-by: William Tu <u9012063@gmail.com>
Cc: Xin Long <lucien.xin@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The phonet_protocol structs don't need to be written by anyone and
so can be marked as const.
Signed-off-by: Lin Zhang <xiaolou4617@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Lin Zhang <xiaolou4617@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Yonghong Song says:

====================
bpf: add two helpers to read perf event enabled/running time

Hardware pmu counters are limited resources. When there are more
pmu based perf events opened than available counters, kernel will
multiplex these events so each event gets certain percentage
(but not 100%) of the pmu time. In case that multiplexing happens,
the number of samples or counter value will not reflect the
case compared to no multiplexing. This makes comparison between
different runs difficult.

Typically, the number of samples or counter value should be
normalized before comparing to other experiments. The typical
normalization is done like:
  normalized_num_samples = num_samples * time_enabled / time_running
  normalized_counter_value = counter_value * time_enabled / time_running
where time_enabled is the time enabled for event and time_running is
the time running for event since last normalization.

This patch set implements two helper functions.
The helper bpf_perf_event_read_value reads counter/time_enabled/time_running
for perf event array map. The helper bpf_perf_prog_read_value read
counter/time_enabled/time_running for bpf prog with type BPF_PROG_TYPE_PERF_EVENT.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The bpf sample program trace_event is enhanced to use the new
helper to print out enabled/running time.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch adds helper bpf_perf_prog_read_cvalue for perf event based bpf
programs, to read event counter and enabled/running time.
The enabled/running time is accumulated since the perf event open.

The typical use case for perf event based bpf program is to attach itself
to a single event. In such cases, if it is desirable to get scaling factor
between two bpf invocations, users can can save the time values in a map,
and use the value from the map and the current value to calculate
the scaling factor.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

The bpf sample program tracex6 is enhanced to use the new
helper to read enabled/running time as well.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

Hardware pmu counters are limited resources. When there are more
pmu based perf events opened than available counters, kernel will
multiplex these events so each event gets certain percentage
(but not 100%) of the pmu time. In case that multiplexing happens,
the number of samples or counter value will not reflect the
case compared to no multiplexing. This makes comparison between
different runs difficult.

Typically, the number of samples or counter value should be
normalized before comparing to other experiments. The typical
normalization is done like:
  normalized_num_samples = num_samples * time_enabled / time_running
  normalized_counter_value = counter_value * time_enabled / time_running
where time_enabled is the time enabled for event and time_running is
the time running for event since last normalization.

This patch adds helper bpf_perf_event_read_value for kprobed based perf
event array map, to read perf counter and enabled/running time.
The enabled/running time is accumulated since the perf event open.
To achieve scaling factor between two bpf invocations, users
can can use cpu_id as the key (which is typical for perf array usage model)
to remember the previous value and do the calculation inside the
bpf program.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch does not impact existing functionalities.
It contains the changes in perf event area needed for
subsequent bpf_perf_event_read_value and
bpf_perf_prog_read_value helpers.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

This commit introduces the MPLSoGRE support (RFC 4023), using ip tunnel
API by simply adding ipgre_tunnel_encap_(add|del)_mpls_ops() and the new
tunnel type TUNNEL_ENCAP_MPLS.
Signed-off-by: Amine Kherbouche <amine.kherbouche@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Wei Wang says:

====================
ipv6: replace rwlock with rcu and spinlock in fib6 table

Currently, fib6 table is protected by rwlock. During route lookup,
reader lock is taken and during route insertion, deletion or
modification, writer lock is taken. This is a very inefficient
implementation because the fastpath always has to do the operation
to grab the reader lock.
According to my latest syn flood test on an iota ivybridage machine
with 2 10G mlx nics bonded together, each with 8 rx queues on 2 NUMA
nodes, and with the upstream net-next kernel:
ipv4 stack can handle around 4.2Mpps
ipv6 stack can handle around 1.3Mpps

In order to close the gap of the performance number between ipv4
and ipv6 stack, this patch series tries to get rid of the usage of
the rwlock and replace it with rcu and spinlock protection. This will
greatly speed up the fastpath performance as it only needs to hold
rcu which is much less expensive than grabbing the reader lock. It
also makes ipv6 fib implementation more consistent with ipv4.

In order to be able to replace the current rwlock with rcu and
spinlock, some preparation work is needed:
Patch 1-8 introduces a per-route hash table (protected by rcu and a
different spinlock) to store all cached routes created by pmtu and ip
redirect under its main route. This makes the main fib6 tree only
contain static routes.
Patch 9-14 prepares all the reader path to be ready to tolerate
concurrent writer.
Patch 15 finally does the rwlock to rcu and spinlock conversion.
Patch 16 takes care of rt6_stats.

After this patch series, in the same syn flood test,
ipv6 stack can now handle around 3.5Mpps compared to previous 1.3Mpps
in my test setup.

After this patch series, there are still some improvements that should
be done in ipv6 stack:
1. During route lookup, dst_use() is called everytime on the selected
route to update dst->__use and dst->lastuse. This dirties the cacheline
and causes extra cacheline miss and should be avoided.
2. when no route is found in the current table, net->ip6.ipv6_null_entry
is used and refcnt is taken on it. As there is no pcpu cache for this
specific route, frequent change on the refcnt for this route causes
quite some cacheline misses.
And to make things worse, if CONFIG_IPV6_MULTIPLE_TABLES is defined,
output path route lookup always starts with local table first and
guarantees to hit net->ipv6.ip6_null_entry before continuing to do
lookup in the main table.
These operations on net->ipv6.ip6_null_entry could potentially be
avoided.
3. ipv6 input path route lookup grabs refcnt on dst. This is different
from ipv4. We could potentially change this behavior to let ipv6 input
path route lookup not to grab refcnt on dst. However, it does not give
us much performance boost as we currently have pcpu route cache for
input path as well in ipv6. But this work probably is still worth doing
to unify ipv6 and ipv4 route lookup behavior.

The above issues will be addressed separately after this patch series
has been accepted.

This is a joint work with Martin KaFai Lau and Eric Dumazet. And many
many thanks to them for their inspiring ideas and big big code review
efforts.
====================
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently, most of the rt6_stats are not hooked up correctly. As the
last part of this patch series, hook up all existing rt6_stats and add
one new stat fib_rt_uncache to indicate the number of routes in the
uncached list.
For details of the stats, please refer to the comments added in
include/net/ip6_fib.h.

Note: fib_rt_alloc and fib_rt_uncache are not guaranteed to be modified
under a lock. So atomic_t is used for them.
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

With all the preparation work before, we are now ready to replace rwlock
with rcu and spinlock in fib6_table.
That means now all fib6_node in fib6_table are protected by rcu. And
when freeing fib6_node, call_rcu() is used to wait for the rcu grace
period before releasing the memory.
When accessing fib6_node, corresponding rcu APIs need to be used.
And all previous sessions protected by the write lock will now be
protected by the spin lock per table.
All previous sessions protected by read lock will now be protected by
rcu_read_lock().

A couple of things to note here:
1. As part of the work of replacing rwlock with rcu, the linked list of
fn->leaf now has to be rcu protected as well. So both fn->leaf and
rt->dst.rt6_next are now __rcu tagged and corresponding rcu APIs are
used when manipulating them.

2. For fn->rr_ptr, first of all, it also needs to be rcu protected now
and is tagged with __rcu and rcu APIs are used in corresponding places.
Secondly, fn->rr_ptr is changed in rt6_select() which is a reader
thread. This makes the issue a bit complicated. We think a valid
solution for it is to let rt6_select() grab the tb6_lock if it decides
to change it. As it is not in the normal operation and only happens when
there is no valid neighbor cache for the route, we think the performance
impact should be low.

3. fib6_walk_continue() has to be called with tb6_lock held even in the
route dumping related functions, e.g. inet6_dump_fib(),
fib6_tables_dump() and ipv6_route_seq_ops. It is because
fib6_walk_continue() makes modifications to the walker structure, and so
are fib6_repair_tree() and fib6_del_route(). In order to do proper
syncing between them, we need to let fib6_walk_continue() hold the lock.
We may be able to do further improvement on the way we do the tree walk
to get rid of the need for holding the spin lock. But not for now.

4. When fib6_del_route() removes a route from the tree, we no longer
mark rt->dst.rt6_next to NULL to make simultaneous reader be able to
further traverse the list with rcu. However, rt->dst.rt6_next is only
valid within this same rcu period. No one should access it later.

5. All the operation of atomic_inc(rt->rt6i_ref) is changed to be
performed before we publish this route (either by linking it to fn->leaf
or insert it in the list pointed by fn->leaf) just to be safe because as
soon as we publish the route, some read thread will be able to access it.
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>