bonding: simplify bond_3ad_update_lacp_rate and use RTNL for sync

We can drop the use of bond->lock for mutual exclusion in
bond_3ad_update_lacp_rate and use RTNL in the sysfs store function
instead. This way we'll prevent races with mode change and interface
up/down as well as simplify update_lacp_rate by removing the check for
port->slave because it'll always be initialized (done while enslaving
with RTNL). This change will also help in the future removal of reader
bond->lock from bond_enslave.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 7 insertions, 8 deletions

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index 90102652c82a..0d8f427ade93 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -2514,17 +2514,13 @@ int bond_3ad_lacpdu_recv(const struct sk_buff *skb, struct bonding *bond,
  */
 void bond_3ad_update_lacp_rate(struct bonding *bond)
 {
-        struct slave *slave;
         struct port *port = NULL;
+        struct slave *slave;
         int lacp_fast;
 
-        write_lock_bh(&bond->lock);
         lacp_fast = bond->params.lacp_fast;
-
         bond_for_each_slave(bond, slave) {
                 port = &(SLAVE_AD_INFO(slave).port);
-                if (port->slave == NULL)
-                        continue;
                 __get_state_machine_lock(port);
                 if (lacp_fast)
                         port->actor_oper_port_state |= AD_STATE_LACP_TIMEOUT;
@@ -2532,6 +2528,4 @@ void bond_3ad_update_lacp_rate(struct bonding *bond)
                         port->actor_oper_port_state &= ~AD_STATE_LACP_TIMEOUT;
                 __release_state_machine_lock(port);
         }
-
-        write_unlock_bh(&bond->lock);
 }
diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 0f539de640dc..ce4677668e2c 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -852,8 +852,11 @@ static ssize_t bonding_store_lacp(struct device *d,
                                   struct device_attribute *attr,
                                   const char *buf, size_t count)
 {
-        int new_value, ret = count;
         struct bonding *bond = to_bond(d);
+        int new_value, ret = count;
+
+        if (!rtnl_trylock())
+                return restart_syscall();
 
         if (bond->dev->flags & IFF_UP) {
                 pr_err("%s: Unable to update LACP rate because interface is up.\n",
@@ -883,6 +886,8 @@ static ssize_t bonding_store_lacp(struct device *d,
                 ret = -EINVAL;
         }
 out:
+        rtnl_unlock();
+
         return ret;
 }
 static DEVICE_ATTR(lacp_rate, S_IRUGO | S_IWUSR,