Remove the bonding debug_fs entries when the
module initialization fails. The debug_fs
entries should be removed together with all other
already allocated resources.
Signed-off-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NJay Vosburgh <j.vosburgh@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

bond_open is not setting the inactive flag correctly for some modes (alb and
tlb), resulting in error behavior if the bond has been administratively set
down and then back up. This effect should not occur when slaves are added while
the bond is up; it's something that only happens after a down/up bounce of the
bond.

For example, in bond tlb or alb mode, domu send some ARP request which go out
from dom0 bond's active slave, then the ARP broadcast request packets go back to
inactive slave from switch, because the inactive slave's inactive flag is zero,
kernel will receive the packets and pass them to bridge that cause dom0's bridge
map domu's MAC address to port of bond, bridge should map domu's MAC to port of
vif.
Signed-off-by: NZheng Li <zheng.x.li@oracle.com>
Signed-off-by: NJay Vosburgh <j.vosburgh@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The gfp parameter was added in:
commit 47be03a2
Author: Amerigo Wang <amwang@redhat.com>
Date:   Fri Aug 10 01:24:37 2012 +0000

    netpoll: use GFP_ATOMIC in slave_enable_netpoll() and __netpoll_setup()

    slave_enable_netpoll() and __netpoll_setup() may be called
    with read_lock() held, so should use GFP_ATOMIC to allocate
    memory. Eric suggested to pass gfp flags to __netpoll_setup().

    Cc: Eric Dumazet <eric.dumazet@gmail.com>
    Cc: "David S. Miller" <davem@davemloft.net>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NCong Wang <amwang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The reason for the gfp parameter was removed in:
commit c4cdef9b
Author: dingtianhong <dingtianhong@huawei.com>
Date:   Tue Jul 23 15:25:27 2013 +0800

    bonding: don't call slave_xxx_netpoll under spinlocks

    The slave_xxx_netpoll will call synchronize_rcu_bh(),
    so the function may schedule and sleep, it should't be
    called under spinlocks.

    bond_netpoll_setup() and bond_netpoll_cleanup() are always
    protected by rtnl lock, it is no need to take the read lock,
    as the slave list couldn't be changed outside rtnl lock.
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
    Cc: Jay Vosburgh <fubar@us.ibm.com>
    Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Nothing else that calls __netpoll_setup or ndo_netpoll_setup
requires a gfp paramter, so remove the gfp parameter from both
of these functions making the code clearer.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove the unnecessary log and add net_ratelimit to the others, in order to
avoid spam the log.

Cc: Joe Perches <joe@perches.com>
Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The bond send arp request to indicate that the slave is active, and if the bond dev
is a vlan dev, it will set the vlan tag in skb to notice the vlan group, but the
bond could only send a skb with 802.1q proto, not support for QinQ.

So add outer tag for lower vlan tag and inner tag for upper vlan tag to support QinQ,
The new skb will be consist of two vlan tag just like this:

dst mac | src mac | outer vlan tag | inner vlan tag | data | .....

If We don't need QinQ, the inner vlan tag could be set to 0 and use outer vlan tag
 as a normal vlan group.

Using "ip link" to configure the bond for QinQ and add test log:

ip link add link bond0  bond0.20 type vlan proto 802.1ad id 20
ip link add link bond0.20  bond0.20.200 type vlan proto 802.1q id 200

ifconfig bond0.20 11.11.20.36/24
ifconfig bond0.20.200 11.11.200.36/24

echo +11.11.200.37 > /sys/class/net/bond0/bonding/arp_ip_target

90:e2:ba:07:4a:5c (oui Unknown) > Broadcast, ethertype 802.1Q-QinQ (0x88a8),length 50: vlan 20, p 0,ethertype 802.1Q, vlan 200, p 0, ethertype ARP, Ethernet (len 6), IPv4 (len 4), Request who-has 11.11.200.37 tell 11.11.200.36, length 28

90:e2:ba:06:f9:86 (oui Unknown) > 90:e2:ba:07:4a:5c (oui Unknown), ethertype 802.1Q-QinQ (0x88a8), length 50: vlan 20, p 0, ethertype 802.1Q, vlan 200, p 0, ethertype ARP, Ethernet (len 6), IPv4 (len 4), Reply 11.11.200.37 is-at 90:e2:ba:06:f9:86 (oui Unknown), length 28

v1->v2: remove the comment "TODO: QinQ?".

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It may spam if the system is out of the memory, add ratelimit for it.
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add unlikely() micro to the unlikely conditions in the bond
xmit path for slight optimization.
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Replace kfree_skb with dev_kfree_skb_any in functions that can
be called in hard irq and other contexts.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make local functions static (ie. only used in bond_options.c)
Make bond options parsing tables constant.
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

These functions are defined but no longer used.
Compile tested only.
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Reviewed-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently we're only sending arp requests if we have a route to the target
(and, thus, can find out the source ip address).

There are some use cases, however, where we don't want/need to set an ip
address (or set up a specific route) for bonding to use arp monitoring *for
traffic generation*. We can easily send arp probes (arp requests with src
ip == 0) to generate arp broadcast responses from the target ip and use
them for determining if the target is up.

This, obviously, won't work with arp validation - because we don't have the
ip address set and, thus, will filter out the responses. So in that case -
print a warning.

CC: François CACHEREUL <f.cachereul@alphalink.fr>
CC: Zhenjie Chen <zhchen@redhat.com>
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Enslaving a bond to itself leads to an endless loop and hangs the kernel.
Signed-off-by: NJiri Bohac <jbohac@suse.cz>
Tested-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There's a bug in the slave release function which leads the transmit
functions which use the bond->slave_cnt to a div by 0 because we might
just have released our last slave and made slave_cnt == 0 but at the same
time we may have a transmitter after the check for an empty list which will
fetch it and use it in the slave id calculation.
Fix it by moving the slave_cnt after synchronize_rcu so if this was our
last slave any new transmitters will see an empty slave list which is
checked after rcu lock but before calling the mode transmit functions
which rely on bond->slave_cnt.

Fixes: 278b2083 ("bonding: initial RCU conversion")

CC: Veaceslav Falico <vfalico@redhat.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: David S. Miller <davem@davemloft.net>
Signed-off-by: NNikolay Aleksandrov <nikolay@redhat.com>
Acked-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Veaceslav has reported and fix this problem by commit f2ebd477
(bonding: restructure locking of bond_ab_arp_probe()). According Jay's
opinion, the current solution is not very well, because the notification
is to indicate that the interface has actually changed state in a meaningful
way, but these calls in the ab ARP monitor are internal settings of the flags
to allow the ARP monitor to search for a slave to become active when there are
no active slaves. The flag setting to active or backup is to permit the ARP
monitor's response logic to do the right thing when deciding if the test
slave (current_arp_slave) is up or not.

So the best way to fix the problem is that we should not send a notification
when the slave is in testing state, and check the state at the end of the
monitor, if the slave's state recover, avoid to send pointless notification
twice. And RTNL is really a big lock, hold it regardless the slave's state
changed or not when the current_active_slave is null will loss performance
(every 100ms), so we should hold it only when the slave's state changed and
need to notify.

I revert the old commit and add new modifications.

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The problem was introduced by the commit 1d3ee88a
(bonding: add netlink attributes to slave link dev).
The bond_set_active_slave() and bond_set_backup_slave()
will use rtmsg_ifinfo to send slave's states, so these
two functions should be called in RTNL.

In 802.3ad mode, acquiring RTNL for the __enable_port and
__disable_port cases is difficult, as those calls generally
already hold the state machine lock, and cannot unconditionally
call rtnl_lock because either they already hold RTNL (for calls
via bond_3ad_unbind_slave) or due to the potential for deadlock
with bond_3ad_adapter_speed_changed, bond_3ad_adapter_duplex_changed,
bond_3ad_link_change, or bond_3ad_update_lacp_rate.  All four of
those are called with RTNL held, and acquire the state machine lock
second.  The calling contexts for __enable_port and __disable_port
already hold the state machine lock, and may or may not need RTNL.

According to the Jay's opinion, I don't think it is a problem that
the slave don't send notify message synchronously when the status
changed, normally the state machine is running every 100 ms, send
the notify message at the end of the state machine if the slave's
state changed should be better.

I fix the problem through these steps:

1). add a new function bond_set_slave_state() which could change
    the slave's state and call rtmsg_ifinfo() according to the input
    parameters called notify.

2). Add a new slave parameter which called should_notify, if the slave's state
    changed and don't notify yet, the parameter will be set to 1, and then if
    the slave's state changed again, the param will be set to 0, it indicate that
    the slave's state has been restored, no need to notify any one.

3). the __enable_port and __disable_port should not call rtmsg_ifinfo
    in the state machine lock, any change in the state of slave could
    set a flag in the slave, it will indicated that an rtmsg_ifinfo
    should be called at the end of the state machine.

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The bond_xxx_info_query() was already in RTNL, so no need to use
bond lock to protect the bond slave list, so remove it.

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The __netpoll_setup() will check the slave's flag and ndo_poll_controller just
like the slave_dev_support_netpoll() does, and slave_dev_support_netpoll() was
not used by any place, so remove it.

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

bond->curr_active_slave can be changed between its deferences, even to
NULL, and thus we might panic.

We're always holding the rcu (rx_handler->bond_handle_frame()->bond_arp_rcv())
so fix this by rcu_dereferencing() it and using the saved.
Reported-by: NDing Tianhong <dingtianhong@huawei.com>
Fixes: aeea64ac ("bonding: don't trust arp requests unless active slave really works")
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Acked-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It's smaller and faster for some architectures.
Signed-off-by: NJoe Perches <joe@perches.com>
Reviewed-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

To reflect the new meaning.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

slave->jiffies is updated every time the slave becomes active, which, for
bonding, means that its link is 'up'.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that all the logic is handled via last_arp_rx, we don't need to use
last_rx.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that last_arp_rx correctly show the last time we've received an ARP, we
can use it safely instead of slave->dev->last_rx.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that the options are in place - arp_validate can be set to receive all
the traffic or only arp packets to verify if the slave is up, when the
slave isn't validated.

CC: Rob Landley <rob@landley.net>
CC: "David S. Miller" <davem@davemloft.net>
CC: Nikolay Aleksandrov <nikolay@redhat.com>
CC: Ding Tianhong <dingtianhong@huawei.com>
CC: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently we only set bond_arp_rcv() if we're using arp_validate, however
this makes us skip updating last_arp_rx if we're not validating incoming
ARPs - thus, if arp_validate is off, last_arp_rx will never be updated.

Fix this by always setting up recv_probe = bond_arp_rcv, even if we're not
using arp_validate.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently we're updating the last_arp_rx only when we've validate the
packet, however afterwards we use it as 'ANY last packet received', but not
only validated ARPs.

Fix this by updating it in case of any packet received. It won't break the
arp_validation=0 because we, anyway, return the correct slave->dev->last_rx in
slave_last_rx().

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently it's disabled because it's sometimes hard, in typical configs, to
make it work - because of the nature how the loadbalance modes work - as
it's hard to deliver valid arp replies to correct slaves by the switch.

However we still can use arp_validation in loadbalance with several other
configs, per example with arp_validate == 2 for backup with one broadcast
domain, without the switch(es) doing any balancing - this way we'd be (a
bit more) sure that the slave is up.

So, enable it to let users decide which one works/suits them best. Also
correct the mode limitation from BOND_OPT_ARP_VALIDATE.

CC: Nikolay Aleksandrov <nikolay@redhat.com>
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Acked-by: NNikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We're always called with rcu_read_lock() held (bond_arp_rcv() is only
called from bond_handle_frame(), which is rx_handler and always called
under rcu from __netif_receive_skb_core() ).

The slave active/passive and/or bonding params can change in-flight, however
we don't really care about that - we only modify the last time packet was
received, which is harmless.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Acked-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a new argument for ndo_select_queue() callback that passes a
fallback handler. This gets invoked through netdev_pick_tx();
fallback handler is currently __netdev_pick_tx() as most drivers
invoke this function within their customized implementation in
case for skbs that don't need any special handling. This fallback
handler can then be replaced on other call-sites with different
queue selection methods (e.g. in packet sockets, pktgen etc).

This also has the nice side-effect that __netdev_pick_tx() is
then only invoked from netdev_pick_tx() and export of that
function to modules can be undone.
Suggested-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ether_addr_copy is smaller and faster for some architectures.

This relies on a stack frame being at least __aligned(2)
for one use of an Ethernet address on the stack.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add missing terminating newlines.
Convert uses of pr_info to pr_cont in bond_check_params.
Standardize upper/lower case styles.
Typo fixes, remove unnecessary parentheses and periods.
Alignment neatening.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use more current logging style.

Coalesce formats, realign arguments, drop unnecessary periods.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The dev_set_mac_address() will check the dev->netdev_ops->ndo_set_mac_address,
so no need to check it in bond_set_mac_address().

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Reviewed-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The bonding driver take write locks and spin locks that are shared
by the tx path in enslave processing and notification processing,
If the netconsole is in use, the bonding can call printk which puts
us in the netpoll tx path, if the netconsole is attached to the bonding
driver, result in deadlock.

So add protection for these place, by checking the netpoll_block_tx
state, we can defer the sending of the netconsole frames until a later
time using the retransmit feature of netpoll_send_skb that is triggered
on the return code NETDEV_TX_BUSY.

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The bond enslave processing don't hold bond->lock anymore,
so release an unlocked rw lock will cause warning message,
remove the unwanted read_unlock(&bond->lock).

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Acked-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The fail_over_mac could be set to active or follow in any time for all modes,
so if the fail_over_mac is not none and the current mode is not active-backup,
the bond_set_mac_address() could not change the master and slave's MAC address.

In bond_set_mac_address(), the fail_over_mac should only affect AB mode, so modify
to check the mode in addition to fail_over_mac when setting bond's MAC address.

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

According to bonding.txt, the fail_over_ma should only affect active-backup mode,
but I found that the fail_over_mac could be set to active or follow in all
modes, this will cause new slave could not be set to bond's MAC address at
enslave processing and restore its own MAC address at removal processing.

The correct way to fix the problem is that we should not add restrictions when
setting options, just need to modify the bond enslave and removal processing
to check the mode in addition to fail_over_mac when setting a slave's MAC during
enslavement. The change active slave processing already only calls the fail_over_mac
function when in active-backup mode.

Thanks for Jay's suggestion.

The patch also modify the pr_warning() to pr_warn().

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The commit 1d3ee88a
(bonding: add netlink attributes to slave link dev)
has add rtmsg_ifinfo() in bond_set_active_slave() and
bond_set_backup_slave(), so the two function need to
called in RTNL lock, but bond_loadbalance_arp_mon()
only calling these functions in RCU, warning message
will occurs.

fix this by add a new function bond_slave_state_change(),
which will reset the slave's state after slave link check,
so remove the bond_set_xxx_slave() from the cycle and only
record the slave_state_changed, this will call the new
function to set all slaves to new state in RTNL later.

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently we're calling it from under RCU context, however we're using some
functions that require rtnl to be held.

Fix this by restructuring the locking - don't call it under any locks,
aquire rcu_read_lock() if we're sending _only_ (i.e. we have the active
slave present), and use rtnl locking otherwise - if we need to modify
(in)active flags of a slave.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently bond_ab_arp_probe() is always called under rcu_read_lock(),
however to work with curr_active_slave we're still holding the
curr_slave_lock.

To remove that curr_slave_lock - rcu_dereference the bond's
curr_active_slave and use it further - so that we're sure the slave won't
go away, and we don't care if it will change in the meanwhile.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>