From 768b954922e69a92a363bd4041cb93040ae4e9cf Mon Sep 17 00:00:00 2001
From: Veaceslav Falico <vfalico@redhat.com>
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 <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
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 da0d7c54d352..b49f421346a7 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;
}
/**