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>

1 files changed, 6 insertions, 1 deletions

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,