From 768b954922e69a92a363bd4041cb93040ae4e9cf Mon Sep 17 00:00:00 2001 From: Veaceslav Falico Date: Fri, 10 Jan 2014 11:59:44 +0100 Subject: [PATCH] bonding: fix __get_first_agg RCU usage Currently, the RCU read lock usage is just wrong - it gets the slave struct under RCU and continues to use it when RCU lock is released. However, it's still safe to do this cause we didn't need the rcu_read_lock() initially - all of the __get_first_agg() callers are either holding RCU read lock or the RTNL lock, so that we can't sync while in it. Fixes: be79bd048 ("bonding: add RCU for bond_3ad_state_machine_handler()") CC: dingtianhong@huawei.com CC: Jay Vosburgh CC: Andy Gospodarek Signed-off-by: Veaceslav Falico Signed-off-by: David S. Miller --- drivers/net/bonding/bond_3ad.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c index da0d7c5..b49f421 100644 --- a/drivers/net/bonding/bond_3ad.c +++ b/drivers/net/bonding/bond_3ad.c @@ -143,11 +143,13 @@ static inline struct bonding *__get_bond_by_port(struct port *port) * * Return the aggregator of the first slave in @bond, or %NULL if it can't be * found. + * The caller must hold RCU or RTNL lock. */ static inline struct aggregator *__get_first_agg(struct port *port) { struct bonding *bond = __get_bond_by_port(port); struct slave *first_slave; + struct aggregator *agg; /* If there's no bond for this port, or bond has no slaves */ if (bond == NULL) @@ -155,9 +157,10 @@ static inline struct aggregator *__get_first_agg(struct port *port) rcu_read_lock(); first_slave = bond_first_slave_rcu(bond); + agg = first_slave ? &(SLAVE_AD_INFO(first_slave).aggregator) : NULL; rcu_read_unlock(); - return first_slave ? &(SLAVE_AD_INFO(first_slave).aggregator) : NULL; + return agg; } /** -- 2.7.4