diff mbox series

[net-next,v2,2/6] rtnetlink: add helper to put master ifindex

Message ID 20170922061008.14723-3-fw@strlen.de
State Superseded, archived
Delegated to: David Miller
Headers show
Series rtnetlink: preparation patches for further rtnl lock pushdown/removal | expand

Commit Message

Florian Westphal Sept. 22, 2017, 6:10 a.m. UTC 
rtnl_fill_ifinfo currently requires caller to hold the rtnl mutex.
Unfortunately the function is quite large which makes it harder to see
which spots need the lock, which spots assume it and which ones could do
without.

Add helpers to factor out the ifindex dumping.

One helper can use rcu to remove rtnl dependency.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/core/rtnetlink.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

Comments

David Ahern Sept. 23, 2017, 5:01 p.m. UTC | #1 
On 9/22/17 12:10 AM, Florian Westphal wrote:
> rtnl_fill_ifinfo currently requires caller to hold the rtnl mutex.
> Unfortunately the function is quite large which makes it harder to see
> which spots need the lock, which spots assume it and which ones could do
> without.
> 
> Add helpers to factor out the ifindex dumping.
> 
> One helper can use rcu to remove rtnl dependency.
> 
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
>  net/core/rtnetlink.c | 32 +++++++++++++++++++++++++++-----
>  1 file changed, 27 insertions(+), 5 deletions(-)

Reviewed-by: David Ahern <dsahern@gmail.com>
diff mbox series

Patch

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index a78fd61da0ec..c801212ee40e 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1307,6 +1307,31 @@  static u32 rtnl_get_event(unsigned long event)
 	return rtnl_event_type;
 }
 
+static int put_master_ifindex(struct sk_buff *skb, struct net_device *dev)
+{
+	const struct net_device *upper_dev;
+	int ret = 0;
+
+	rcu_read_lock();
+
+	upper_dev = netdev_master_upper_dev_get_rcu(dev);
+	if (upper_dev)
+		ret = nla_put_u32(skb, IFLA_MASTER, upper_dev->ifindex);
+
+	rcu_read_unlock();
+	return ret;
+}
+
+static int nla_put_iflink(struct sk_buff *skb, const struct net_device *dev)
+{
+	int ifindex = dev_get_iflink(dev);
+
+	if (dev->ifindex == ifindex)
+		return 0;
+
+	return nla_put_u32(skb, IFLA_LINK, ifindex);
+}
+
 static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
 			    int type, u32 pid, u32 seq, u32 change,
 			    unsigned int flags, u32 ext_filter_mask,
@@ -1316,7 +1341,6 @@  static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
 	struct nlmsghdr *nlh;
 	struct nlattr *af_spec;
 	struct rtnl_af_ops *af_ops;
-	struct net_device *upper_dev = netdev_master_upper_dev_get(dev);
 
 	ASSERT_RTNL();
 	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*ifm), flags);
@@ -1345,10 +1369,8 @@  static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
 #ifdef CONFIG_RPS
 	    nla_put_u32(skb, IFLA_NUM_RX_QUEUES, dev->num_rx_queues) ||
 #endif
-	    (dev->ifindex != dev_get_iflink(dev) &&
-	     nla_put_u32(skb, IFLA_LINK, dev_get_iflink(dev))) ||
-	    (upper_dev &&
-	     nla_put_u32(skb, IFLA_MASTER, upper_dev->ifindex)) ||
+	    nla_put_iflink(skb, dev) ||
+	    put_master_ifindex(skb, dev) ||
 	    nla_put_u8(skb, IFLA_CARRIER, netif_carrier_ok(dev)) ||
 	    (dev->qdisc &&
 	     nla_put_string(skb, IFLA_QDISC, dev->qdisc->ops->id)) ||