bonding: add rtnl protection for bonding_store_fail_over_mac

We need rtnl protection while reading slave_cnt and updating
the .fail_over_mac, and it also follows the logic "don't change
anything slave-related without rtnl". :)

Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 984ca02cfe7572ef0de26c9046c4e8d9e0a23758..ae02c194c01b6909e379144ac68f2dbb8a08a20d 100644 (file)
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -501,20 +501,25 @@ static ssize_t bonding_store_fail_over_mac(struct device *d,
                                           struct device_attribute *attr,
                                           const char *buf, size_t count)
 {
-       int new_value;
+       int new_value, ret = count;
        struct bonding *bond = to_bond(d);
 
+       if (!rtnl_trylock())
+               return restart_syscall();
+
        if (bond->slave_cnt != 0) {
                pr_err("%s: Can't alter fail_over_mac with slaves in bond.\n",
                       bond->dev->name);
-               return -EPERM;
+               ret = -EPERM;
+               goto out;
        }
 
        new_value = bond_parse_parm(buf, fail_over_mac_tbl);
        if (new_value < 0) {
                pr_err("%s: Ignoring invalid fail_over_mac value %s.\n",
                       bond->dev->name, buf);
-               return -EINVAL;
+               ret = -EINVAL;
+               goto out;
        }
 
        bond->params.fail_over_mac = new_value;
@@ -522,7 +527,9 @@ static ssize_t bonding_store_fail_over_mac(struct device *d,
                bond->dev->name, fail_over_mac_tbl[new_value].modename,
                new_value);
 
-       return count;
+out:
+       rtnl_unlock();
+       return ret;
 }
 
 static DEVICE_ATTR(fail_over_mac, S_IRUGO | S_IWUSR,