[PATCH net-next 02/10] bonding: use __dev_get_by_name instead of dev_get_by_name to find interface

Ying Xue
2014-01-14T07:42:12Z

The following call chain indicates that bond_do_ioctl() is protected
under rtnl_lock. If we use __dev_get_by_name() instead of
dev_get_by_name() to find interface handler in it, this would
help us avoid to change reference counter of interface once.

dev_ioctl()
rtnl_lock()
dev_ifsioc()
bond_do_ioctl()
rtnl_unlock()

Additionally we also change the coding style in bond_do_ioctl(),
letting it more readable for us.

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: Ying Xue <ying.xue@windriver.com>
---
drivers/net/bonding/bond_main.c | 49 ++++++++++++++++++---------------------
1 file changed, 23 insertions(+), 26 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index e06c445..a69afbf 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3213,37 +3213,34 @@ static int bond_do_ioctl(struct net_device *bond_dev, struct ifreq *ifr, int cmd
if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
return -EPERM;

- slave_dev = dev_get_by_name(net, ifr->ifr_slave);
+ slave_dev = __dev_get_by_name(net, ifr->ifr_slave);

pr_debug("slave_dev=%p:\n", slave_dev);

if (!slave_dev)
- res = -ENODEV;
- else {
- pr_debug("slave_dev->name=%s:\n", slave_dev->name);
- switch (cmd) {
- case BOND_ENSLAVE_OLD:
- case SIOCBONDENSLAVE:
- res = bond_enslave(bond_dev, slave_dev);
- break;
- case BOND_RELEASE_OLD:
- case SIOCBONDRELEASE:
- res = bond_release(bond_dev, slave_dev);
- break;
- case BOND_SETHWADDR_OLD:
- case SIOCBONDSETHWADDR:
- bond_set_dev_addr(bond_dev, slave_dev);
- res = 0;
- break;
- case BOND_CHANGE_ACTIVE_OLD:
- case SIOCBONDCHANGEACTIVE:
- res = bond_option_active_slave_set(bond, slave_dev);
- break;
- default:
- res = -EOPNOTSUPP;
- }
+ return -ENODEV;

- dev_put(slave_dev);
+ pr_debug("slave_dev->name=%s:\n", slave_dev->name);
+ switch (cmd) {
+ case BOND_ENSLAVE_OLD:
+ case SIOCBONDENSLAVE:
+ res = bond_enslave(bond_dev, slave_dev);
+ break;
+ case BOND_RELEASE_OLD:
+ case SIOCBONDRELEASE:
+ res = bond_release(bond_dev, slave_dev);
+ break;
+ case BOND_SETHWADDR_OLD:
+ case SIOCBONDSETHWADDR:
+ bond_set_dev_addr(bond_dev, slave_dev);
+ res = 0;
+ break;
+ case BOND_CHANGE_ACTIVE_OLD:
+ case SIOCBONDCHANGEACTIVE:
+ res = bond_option_active_slave_set(bond, slave_dev);
+ break;
+ default:
+ res = -EOPNOTSUPP;
}

return res;
--
1.7.9.5