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| author | Nithin Sujir <nsujir@tintri.com> | 2017-05-24 19:45:17 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-05-25 14:47:35 -0400 |
| commit | 797a93647a48d6cb8a20641a86a71713a947f786 (patch) | |
| tree | 834604b4c92ec171f1a6a2c12e4ef33f26fa10a1 | |
| parent | 791caeb084c57e3a4d648cf1ee799d1f70c0ef4e (diff) | |
| download | linux-797a93647a48d6cb8a20641a86a71713a947f786.tar.gz linux-797a93647a48d6cb8a20641a86a71713a947f786.tar.bz2 linux-797a93647a48d6cb8a20641a86a71713a947f786.zip | |
bonding: Don't update slave->link until ready to commit
In the loadbalance arp monitoring scheme, when a slave link change is
detected, the slave->link is immediately updated and slave_state_changed
is set. Later down the function, the rtnl_lock is acquired and the
changes are committed, updating the bond link state.
However, the acquisition of the rtnl_lock can fail. The next time the
monitor runs, since slave->link is already updated, it determines that
link is unchanged. This results in the bond link state permanently out
of sync with the slave link.
This patch modifies bond_loadbalance_arp_mon() to handle link changes
identical to bond_ab_arp_{inspect/commit}(). The new link state is
maintained in slave->new_link until we're ready to commit at which point
it's copied into slave->link.
NOTE: miimon_{inspect/commit}() has a more complex state machine
requiring the use of the bond_{propose,commit}_link_state() functions
which maintains the intermediate state in slave->link_new_state. The arp
monitors don't require that.
Testing: This bug is very easy to reproduce with the following steps.
1. In a loop, toggle a slave link of a bond slave interface.
2. In a separate loop, do ifconfig up/down of an unrelated interface to
create contention for rtnl_lock.
Within a few iterations, the bond link goes out of sync with the slave
link.
Signed-off-by: Nithin Nayak Sujir <nsujir@tintri.com>
Cc: Mahesh Bandewar <maheshb@google.com>
Cc: Jay Vosburgh <jay.vosburgh@canonical.com>
Acked-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/bonding/bond_main.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 73313318399c..2359478b977f 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2612,11 +2612,13 @@ static void bond_loadbalance_arp_mon(struct bonding *bond) bond_for_each_slave_rcu(bond, slave, iter) { unsigned long trans_start = dev_trans_start(slave->dev); + slave->new_link = BOND_LINK_NOCHANGE; + if (slave->link != BOND_LINK_UP) { if (bond_time_in_interval(bond, trans_start, 1) && bond_time_in_interval(bond, slave->last_rx, 1)) { - slave->link = BOND_LINK_UP; + slave->new_link = BOND_LINK_UP; slave_state_changed = 1; /* primary_slave has no meaning in round-robin @@ -2643,7 +2645,7 @@ static void bond_loadbalance_arp_mon(struct bonding *bond) if (!bond_time_in_interval(bond, trans_start, 2) || !bond_time_in_interval(bond, slave->last_rx, 2)) { - slave->link = BOND_LINK_DOWN; + slave->new_link = BOND_LINK_DOWN; slave_state_changed = 1; if (slave->link_failure_count < UINT_MAX) @@ -2674,6 +2676,11 @@ static void bond_loadbalance_arp_mon(struct bonding *bond) if (!rtnl_trylock()) goto re_arm; + bond_for_each_slave(bond, slave, iter) { + if (slave->new_link != BOND_LINK_NOCHANGE) + slave->link = slave->new_link; + } + if (slave_state_changed) { bond_slave_state_change(bond); if (BOND_MODE(bond) == BOND_MODE_XOR) |