[PATCH net-next 04/10] dcb: use __dev_get_by_name instead of dev_get_by_name to find interface

Ying Xue
2014-01-14T07:42:45Z

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

rtnetlink_rcv()
rtnl_lock()
netlink_rcv_skb()
dcb_doit()
rtnl_unlock()

Cc: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: Ying Xue <ying.xue@windriver.com>
---
net/dcb/dcbnl.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/net/dcb/dcbnl.c b/net/dcb/dcbnl.c
index 66fbe19..5536444 100644
--- a/net/dcb/dcbnl.c
+++ b/net/dcb/dcbnl.c
@@ -1688,21 +1688,17 @@ static int dcb_doit(struct sk_buff *skb, struct nlmsghdr *nlh)
if (!tb[DCB_ATTR_IFNAME])
return -EINVAL;

- netdev = dev_get_by_name(net, nla_data(tb[DCB_ATTR_IFNAME]));
+ netdev = __dev_get_by_name(net, nla_data(tb[DCB_ATTR_IFNAME]));
if (!netdev)
return -ENODEV;

- if (!netdev->dcbnl_ops) {
- ret = -EOPNOTSUPP;
- goto out;
- }
+ if (!netdev->dcbnl_ops)
+ return -EOPNOTSUPP;

reply_skb = dcbnl_newmsg(fn->type, dcb->cmd, portid, nlh->nlmsg_seq,
nlh->nlmsg_flags, &reply_nlh);
- if (!reply_skb) {
- ret = -ENOBUFS;
- goto out;
- }
+ if (!reply_skb)
+ return -ENOBUFS;

ret = fn->cb(netdev, nlh, nlh->nlmsg_seq, tb, reply_skb);
if (ret < 0) {
@@ -1714,7 +1710,6 @@ static int dcb_doit(struct sk_buff *skb, struct nlmsghdr *nlh)

ret = rtnl_unicast(reply_skb, net, portid);
out:
- dev_put(netdev);
return ret;
}

--
1.7.9.5