Patchwork [v4,net-next,3/3] bonding: fix __get_active_agg() RCU logic

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Submitter Veaceslav Falico
Date Jan. 10, 2014, 10:59 a.m.
Message ID <1389351585-19615-4-git-send-email-vfalico@redhat.com>
Download mbox | patch
Permalink /patch/309253/
State Accepted
Delegated to: David Miller
Headers show

Comments

Veaceslav Falico - Jan. 10, 2014, 10:59 a.m.
Currently, the implementation is meaningless - once again, we take the
slave structure and use it after we've exited RCU critical section.

Fix this by removing the rcu_read_lock() from __get_active_agg(), and
ensuring that all its callers are holding RCU.

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>
---

Notes:
    v2 -> v3:
    Use the RCU primitives.
    
    v1 -> v2:
    Don't use RCU primitives as we can hold RTNL.

 drivers/net/bonding/bond_3ad.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

Patch

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index b49f421..cce1f1b 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -678,6 +678,8 @@  static u32 __get_agg_bandwidth(struct aggregator *aggregator)
 /**
  * __get_active_agg - get the current active aggregator
  * @aggregator: the aggregator we're looking at
+ *
+ * Caller must hold RCU lock.
  */
 static struct aggregator *__get_active_agg(struct aggregator *aggregator)
 {
@@ -685,13 +687,9 @@  static struct aggregator *__get_active_agg(struct aggregator *aggregator)
 	struct list_head *iter;
 	struct slave *slave;
 
-	rcu_read_lock();
 	bond_for_each_slave_rcu(bond, slave, iter)
-		if (SLAVE_AD_INFO(slave).aggregator.is_active) {
-			rcu_read_unlock();
+		if (SLAVE_AD_INFO(slave).aggregator.is_active)
 			return &(SLAVE_AD_INFO(slave).aggregator);
-		}
-	rcu_read_unlock();
 
 	return NULL;
 }
@@ -1499,11 +1497,11 @@  static void ad_agg_selection_logic(struct aggregator *agg)
 	struct slave *slave;
 	struct port *port;
 
+	rcu_read_lock();
 	origin = agg;
 	active = __get_active_agg(agg);
 	best = (active && agg_device_up(active)) ? active : NULL;
 
-	rcu_read_lock();
 	bond_for_each_slave_rcu(bond, slave, iter) {
 		agg = &(SLAVE_AD_INFO(slave).aggregator);