Add a port function to access the Port Based VLAN Map register.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add the port STP state setter to the port files.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The Marvell switches contains one internal SMI device per port, called
"Port Registers". Depending on the model, the addresses of these devices
start from 0x0, 0x8 or 0x10.

Start moving Port Registers specific code to their own files.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Support matching on SCTP ports in the same way that matching
on TCP and UDP ports is already supported.

Example usage:

tc qdisc add dev eth0 ingress

tc filter add dev eth0 protocol ip parent ffff: \
        flower indev eth0 ip_proto sctp dst_port 80 \
        action drop
Signed-off-by: NSimon Horman <simon.horman@netronome.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The system-status register is actually 16-bit wide and not 8 bit-wide.

Fixes: 233fa44b ("mlxsw: pci: Implement reset done check")
Signed-off-by: NElad Raz <eladr@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Willem de Bruijn says:

====================
ip: add RECVFRAGSIZE cmsg

On IP datagrams and raw sockets, when packets arrive fragmented,
expose the largest received fragment size through a new cmsg.

Protocols implemented on top of these sockets may use this, for
instance, to inform peers to lower MSS on platforms that silently
allow send calls to exceed PMTU and cause fragmentation.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

IP6CB and IPCB have a frag_max_size field. In IPv6 this field is
filled in when packets are reassembled by the connection tracking
code. Also fill in when reassembling in the input path, to expose
it through cmsg IPV6_RECVFRAGSIZE in all cases.
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When reading a datagram or raw packet that arrived fragmented, expose
the maximum fragment size if recorded to allow applications to
estimate receive path MTU.

At this point, the field is only recorded when ipv6 connection
tracking is enabled. A follow-up patch will record this field also
in the ipv6 input path.

Tested using the test for IP_RECVFRAGSIZE plus

  ip netns exec to ip addr add dev veth1 fc07::1/64
  ip netns exec from ip addr add dev veth0 fc07::2/64

  ip netns exec to ./recv_cmsg_recvfragsize -6 -u -p 6000 &
  ip netns exec from nc -q 1 -u fc07::1 6000 < payload

Both with and without enabling connection tracking

  ip6tables -A INPUT -m state --state NEW -p udp -j LOG
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The IP stack records the largest fragment of a reassembled packet
in IPCB(skb)->frag_max_size. When reading a datagram or raw packet
that arrived fragmented, expose the value to allow applications to
estimate receive path MTU.

Tested:
  Sent data over a veth pair of which the source has a small mtu.
  Sent data using netcat, received using a dedicated process.

  Verified that the cmsg IP_RECVFRAGSIZE is returned only when
  data arrives fragmented, and in that cases matches the veth mtu.

    ip link add veth0 type veth peer name veth1

    ip netns add from
    ip netns add to

    ip link set dev veth1 netns to
    ip netns exec to ip addr add dev veth1 192.168.10.1/24
    ip netns exec to ip link set dev veth1 up

    ip link set dev veth0 netns from
    ip netns exec from ip addr add dev veth0 192.168.10.2/24
    ip netns exec from ip link set dev veth0 up
    ip netns exec from ip link set dev veth0 mtu 1300
    ip netns exec from ethtool -K veth0 ufo off

    dd if=/dev/zero bs=1 count=1400 2>/dev/null > payload

    ip netns exec to ./recv_cmsg_recvfragsize -4 -u -p 6000 &
    ip netns exec from nc -q 1 -u 192.168.10.1 6000 < payload

  using github.com/wdebruij/kerneltools/blob/master/tests/recvfragsize.c
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Neil Armstrong says:

====================
net: stmmac: Add OXNAS DWMAC Glue

This patchset add support for the Sysnopsys DWMAC Gigabit Ethernet
controller Glue layer of the Oxford Semiconductor OX820 SoC.

Changes since v2 at http://lkml.kernel.org/r/20161031105345.16711-1-narmstrong@baylibre.com :
 - Disable/Unprepare clock if regmap read fails in oxnas_dwmac_init

Changes since v1 at https://patchwork.kernel.org/patch/9388231/ :
 - Split dt-bindings in a separate patch
 - Add IP version in the dt-bindings compatible
 - Check return of clk_prepare_enable()
 - use get_stmmac_bsp_priv() helper
 - hardwire setup values in oxnas_dwmac_init()

Changes since RFC at https://patchwork.kernel.org/patch/9387257 :
 - Drop init/exit callbacks
 - Implement proper remove and PM callback
 - Call init from probe
 - Disable/Unprepare clock if stmmac probe fails
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NNeil Armstrong <narmstrong@baylibre.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add Synopsys Designware MAC Glue layer for the Oxford Semiconductor OX820.
Acked-by: NJoachim Eastwood <manabian@gmail.com>
Signed-off-by: NNeil Armstrong <narmstrong@baylibre.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Cyrill Gorcunov says:

====================
net: Fixes for raw diag sockets handling

Hi! Here are a few fixes for raw-diag sockets handling: missing
sock_put call and jump for exiting from nested cycle. I made
patches for iproute2 as well so will send them out soon.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

I managed to miss that sk_for_each is called under "for"
cycle so need to use goto here to return matching socket.

CC: David S. Miller <davem@davemloft.net>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: David Ahern <dsa@cumulusnetworks.com>
CC: Andrey Vagin <avagin@openvz.org>
CC: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Acked-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In raw_diag_destroy the helper raw_sock_get returns
with sock_hold call, so we have to put it then.

CC: David S. Miller <davem@davemloft.net>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: David Ahern <dsa@cumulusnetworks.com>
CC: Andrey Vagin <avagin@openvz.org>
CC: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Acked-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Driver sets the skb l4/l3 hash based on NIC_CFG_RSS_HASH_TYPE_*,
which is bit mask. This is wrong. Hw actually provides us enum.
Use CQ_ENET_RQ_DESC_RSS_TYPE_* to set l3 and l4 hash type.

Fixes: bf751ba8 ("driver/net: enic: record q_number and rss_hash for skb")
Signed-off-by: NGovindarajulu Varadarajan <_govind@gmx.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The ethtool api {get|set}_settings is deprecated.
We move this driver to new api {get|set}_link_ksettings.
Signed-off-by: NPhilippe Reynes <tremyfr@gmail.com>
Reviewed-by: NDavid Dillow <dave@thedillows.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

commit ca26893f ("rhashtable: Add rhlist interface")
added a field to rhashtable_iter so that length became 56 bytes
and would exceed the size of args in netlink_callback (which is
48 bytes). The netlink diag dump function already has been
allocating a iter structure and storing the pointed to that
in the args of netlink_callback. ila_xlat also uses
rhahstable_iter but is still putting that directly in
the arg block. Now since rhashtable_iter size is increased
we are overwriting beyond the structure. The next field
happens to be cb_mutex pointer in netlink_sock and hence the crash.

Fix is to alloc the rhashtable_iter and save it as pointer
in arg.

Tested:

  modprobe ila
  ./ip ila add loc 3333:0:0:0 loc_match 2222:0:0:1,
  ./ip ila list  # NO crash now
Signed-off-by: NTom Herbert <tom@herbertland.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

While being preparing patches for killing raw sockets via
diag netlink interface I noticed that my runs are stuck:

 | [root@pcs7 ~]# cat /proc/`pidof ss`/stack
 | [<ffffffff816d1a76>] __lock_sock+0x80/0xc4
 | [<ffffffff816d206a>] lock_sock_nested+0x47/0x95
 | [<ffffffff8179ded6>] udp_disconnect+0x19/0x33
 | [<ffffffff8179b517>] raw_abort+0x33/0x42
 | [<ffffffff81702322>] sock_diag_destroy+0x4d/0x52

which has not been the case before. I narrowed it down to the commit

 | commit 286c72de
 | Author: Eric Dumazet <edumazet@google.com>
 | Date:   Thu Oct 20 09:39:40 2016 -0700
 |
 |     udp: must lock the socket in udp_disconnect()

where we start locking the socket for different reason.

So the raw_abort escaped the renaming and we have to
fix this typo using __udp_disconnect instead.

Fixes: 286c72de ("udp: must lock the socket in udp_disconnect()")
CC: David S. Miller <davem@davemloft.net>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: David Ahern <dsa@cumulusnetworks.com>
CC: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
CC: James Morris <jmorris@namei.org>
CC: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
CC: Patrick McHardy <kaber@trash.net>
CC: Andrey Vagin <avagin@openvz.org>
CC: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

To utilize phylib with interrupt fully than handling some of phy stuff in the MAC driver,
create irq_domain for USB interrupt EP of phy interrupt and
pass the irq number to phy_connect_direct() instead of PHY_IGNORE_INTERRUPT.

Idea comes from drivers/gpio/gpio-dl2.c
Signed-off-by: NWoojung Huh <woojung.huh@microchip.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As Ilya Lesokhin suggested, we can collapse two skbs at retransmit
time even if the skb at the right has fragments.

We simply have to use more generic skb_copy_bits() instead of
skb_copy_from_linear_data() in tcp_collapse_retrans()

Also need to guard this skb_copy_bits() in case there is nothing to
copy, otherwise skb_put() could panic if left skb has frags.

Tested:

Used following packetdrill test

// Establish a connection.
0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
   +0 bind(3, ..., ...) = 0
   +0 listen(3, 1) = 0

   +0 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 8>
   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+.100 < . 1:1(0) ack 1 win 257
   +0 accept(3, ..., ...) = 4

   +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0
   +0 write(4, ..., 200) = 200
   +0 > P. 1:201(200) ack 1
+.001 write(4, ..., 200) = 200
   +0 > P. 201:401(200) ack 1
+.001 write(4, ..., 200) = 200
   +0 > P. 401:601(200) ack 1
+.001 write(4, ..., 200) = 200
   +0 > P. 601:801(200) ack 1
+.001 write(4, ..., 200) = 200
   +0 > P. 801:1001(200) ack 1
+.001 write(4, ..., 100) = 100
   +0 > P. 1001:1101(100) ack 1
+.001 write(4, ..., 100) = 100
   +0 > P. 1101:1201(100) ack 1
+.001 write(4, ..., 100) = 100
   +0 > P. 1201:1301(100) ack 1
+.001 write(4, ..., 100) = 100
   +0 > P. 1301:1401(100) ack 1

+.100 < . 1:1(0) ack 1 win 257 <nop,nop,sack 1001:1401>
// Check that TCP collapse works :
   +0 > P. 1:1001(1000) ack 1
Reported-by: NIlya Lesokhin <ilyal@mellanox.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The ethtool api {get|set}_settings is deprecated.
We move this driver to new api {get|set}_link_ksettings.
Signed-off-by: NPhilippe Reynes <tremyfr@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The ethtool api {get|set}_settings is deprecated.
We move this driver to new api {get|set}_link_ksettings.
Signed-off-by: NPhilippe Reynes <tremyfr@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The old ethtool api (get_setting and set_setting) has generic mii
functions mii_ethtool_sset and mii_ethtool_gset.

To support the new ethtool api ({get|set}_link_ksettings), we add
two generics mii function mii_ethtool_{get|set}_link_ksettings_get.
Signed-off-by: NPhilippe Reynes <tremyfr@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Tariq Toukan says:

====================
mlx4 XDP TX refactor

This patchset refactors the XDP forwarding case, so that
its dedicated transmit queues are managed in a complete
separation from the other regular ones.

It also adds ethtool counters for XDP cases.

Series generated against net-next commit:
22ca904a genetlink: fix error return code in genl_register_family()

Thanks,
Tariq.

v3:
* Exposed per ring counters.

v2:
* Added ethtool counters.
* Rebased, now patch 2 reverts Brenden's fix, as the bug no longer exists:
  958b3d39 ("net/mlx4_en: fixup xdp tx irq to match rx")
* Updated commit message of patch 2.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

XDP statistics are reported in ethtool, in total and per ring,
as follows:
- xdp_drop: the number of packets dropped by xdp.
- xdp_tx: the number of packets forwarded by xdp.
- xdp_tx_full: the number of times an xdp forward failed
	due to a full tx xdp ring.

In addition, all packets that are dropped/forwarded by XDP
are no longer accounted in rx_packets/rx_bytes of the ring,
so that they count traffic that is passed to the stack.
Signed-off-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Separately manage the two types of TX rings: regular ones, and XDP.
Upon an XDP set, do not borrow regular TX rings and convert them
into XDP ones, but allocate new ones, unless we hit the max number
of rings.
Which means that in systems with smaller #cores we will not consume
the current TX rings for XDP, while we are still in the num TX limit.

XDP TX rings counters are not shown in ethtool statistics.
Instead, XDP counters will be added to the respective RX rings
in a downstream patch.

This has no performance implications.
Signed-off-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Support XDP CQ type, and refactor the CQ type enum.
Rename the is_tx field to match the change.
Signed-off-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After adding sctp gso, sctp_packet_transmit is a quite big function now.

This patch is to extract the codes for packing packet to sctp_packet_pack
from sctp_packet_transmit, and add some comments, simplify the err path by
freeing auth chunk when freeing packet chunk_list in out path and freeing
head skb early if it fails to pack packet.
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Acked-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Roi Dayan says:

====================
misc TC/flower changes

This series includes two small changes to the TC flower classifier.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Move common code from fl_delete and fl_detroy to __fl_delete.
Signed-off-by: NRoi Dayan <roid@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tcf_unbind was called in fl_delete but was missing in fl_destroy when
force deleting flows.

Fixes: 77b9900e ('tc: introduce Flower classifier')
Signed-off-by: NRoi Dayan <roid@mellanox.com>
Reviewed-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pablo Neira Ayuso says:

====================
Netfilter updates for net-next

The following patchset contains Netfilter updates for your net-next
tree. This includes better integration with the routing subsystem for
nf_tables, explicit notrack support and smaller updates. More
specifically, they are:

1) Add fib lookup expression for nf_tables, from Florian Westphal. This
   new expression provides a native replacement for iptables addrtype
   and rp_filter matches. This is more flexible though, since we can
   populate the kernel flowi representation to inquire fib to
   accomodate new usecases, such as RTBH through skb mark.

2) Introduce rt expression for nf_tables, from Anders K. Pedersen. This
   new expression allow you to access skbuff route metadata, more
   specifically nexthop and classid fields.

3) Add notrack support for nf_tables, to skip conntracking, requested by
   many users already.

4) Add boilerplate code to allow to use nf_log infrastructure from
   nf_tables ingress.

5) Allow to mangle pkttype from nf_tables prerouting chain, to emulate
   the xtables cluster match, from Liping Zhang.

6) Move socket lookup code into generic nf_socket_* infrastructure so
   we can provide a native replacement for the xtables socket match.

7) Make sure nfnetlink_queue data that is updated on every packets is
   placed in a different cache from read-only data, from Florian Westphal.

8) Handle NF_STOLEN from nf_tables core, also from Florian Westphal.

9) Start round robin number generation in nft_numgen from zero,
   instead of n-1, for consistency with xtables statistics match,
   patch from Liping Zhang.

10) Set GFP_NOWARN flag in skbuff netlink allocations in nfnetlink_log,
    given we retry with a smaller allocation on failure, from Calvin Owens.

11) Cleanup xt_multiport to use switch(), from Gao feng.

12) Remove superfluous check in nft_immediate and nft_cmp, from
    Liping Zhang.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As the comment indicates, the data at the end of nfqnl_instance struct is
written on every queue/dequeue, so it should reside in its own cacheline.

Before this change, 'lock' was in first cacheline so we dirtied both.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

After call nft_data_init, size is already validated and desc.len will
not exceed the sizeof(struct nft_data), i.e. 16 bytes. So it will never
exceed U8_MAX.

Furthermore, in nft_immediate_init, we forget to call nft_data_uninit
when desc.len exceeds U8_MAX, although this will not happen, but it's
a logical mistake.

Now remove these redundant validation introduced by commit 36b701fa
("netfilter: nf_tables: validate maximum value of u32 netlink attributes")
Signed-off-by: NLiping Zhang <zlpnobody@gmail.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Introduces an nftables rt expression for routing related data with support
for nexthop (i.e. the directly connected IP address that an outgoing packet
is sent to), which can be used either for matching or accounting, eg.

 # nft add rule filter postrouting \
	ip daddr 192.168.1.0/24 rt nexthop != 192.168.0.1 drop

This will drop any traffic to 192.168.1.0/24 that is not routed via
192.168.0.1.

 # nft add rule filter postrouting \
	flow table acct { rt nexthop timeout 600s counter }
 # nft add rule ip6 filter postrouting \
	flow table acct { rt nexthop timeout 600s counter }

These rules count outgoing traffic per nexthop. Note that the timeout
releases an entry if no traffic is seen for this nexthop within 10 minutes.

 # nft add rule inet filter postrouting \
	ether type ip \
	flow table acct { rt nexthop timeout 600s counter }
 # nft add rule inet filter postrouting \
	ether type ip6 \
	flow table acct { rt nexthop timeout 600s counter }

Same as above, but via the inet family, where the ether type must be
specified explicitly.

"rt classid" is also implemented identical to "meta rtclassid", since it
is more logical to have this match in the routing expression going forward.
Signed-off-by: NAnders K. Pedersen <akp@cohaesio.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

We need this split to reuse existing codebase for the upcoming nf_tables
socket expression.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Move layer 2 packet logging into nf_log_l2packet() that resides in
nf_log_common.c, so this can be shared by both bridge and netdev
families.

This patch adds the boiler plate code to register the netdev logging
family.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Add FIB expression, supported for ipv4, ipv6 and inet family (the latter
just dispatches to ipv4 or ipv6 one based on nfproto).

Currently supports fetching output interface index/name and the
rtm_type associated with an address.

This can be used for adding path filtering. rtm_type is useful
to e.g. enforce a strong-end host model where packets
are only accepted if daddr is configured on the interface the
packet arrived on.

The fib expression is a native nftables alternative to the
xtables addrtype and rp_filter matches.

FIB result order for oif/oifname retrieval is as follows:
 - if packet is local (skb has rtable, RTF_LOCAL set, this
   will also catch looped-back multicast packets), set oif to
   the loopback interface.
 - if fib lookup returns an error, or result points to local,
   store zero result.  This means '--local' option of -m rpfilter
   is not supported. It is possible to use 'fib type local' or add
   explicit saddr/daddr matching rules to create exceptions if this
   is really needed.
 - store result in the destination register.
   In case of multiple routes, search set for desired oif in case
   strict matching is requested.

ipv4 and ipv6 behave fib expressions are supposed to behave the same.

[ I have collapsed Arnd Bergmann's ("netfilter: nf_tables: fib warnings")

	http://patchwork.ozlabs.org/patch/688615/

  to address fallout from this patch after rebasing nf-next, that was
  posted to address compilation warnings. --pablo ]
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Fix to return a negative error code from the idr_alloc() error handling
case instead of 0, as done elsewhere in this function.

Also fix the return value check of idr_alloc() since idr_alloc return
negative errors on failure, not zero.

Fixes: 2ae0f17d ("genetlink: use idr to track families")
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>