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authorNithin Sujir <nsujir@tintri.com>2017-05-24 19:45:17 -0700
committerDavid S. Miller <davem@davemloft.net>2017-05-25 14:47:35 -0400
commit797a93647a48d6cb8a20641a86a71713a947f786 (patch)
tree834604b4c92ec171f1a6a2c12e4ef33f26fa10a1 /drivers
parent791caeb084c57e3a4d648cf1ee799d1f70c0ef4e (diff)
downloadleg-kernel-797a93647a48d6cb8a20641a86a71713a947f786.tar.gz
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/bonding/bond_main.c11
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)