phonet netlink: allow multiple messages per skb in route dump

My previous patch to this file changed the code to be bug-compatible
towards userspace. Unless userspace (which I wasn't able to find)
implements the dump reader by hand in a wrong way, this isn't needed.
If it uses libnl or similar code putting multiple messages into a
single SKB is far more efficient.

Change the code to do this. While at it, also clean it up and don't
use so many variables - just store the address in the callback args
directly.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 15 deletions

diff --git a/net/phonet/pn_netlink.c b/net/phonet/pn_netlink.c
index 54d766842c2b..bc5ee5fbe6ae 100644
--- a/net/phonet/pn_netlink.c
+++ b/net/phonet/pn_netlink.c
@@ -272,31 +272,23 @@ static int route_doit(struct sk_buff *skb, struct nlmsghdr *nlh)
 static int route_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 {
         struct net *net = sock_net(skb->sk);
-        u8 addr, addr_idx = 0, addr_start_idx = cb->args[0];
+        u8 addr;
 
         rcu_read_lock();
-        for (addr = 0; addr < 64; addr++) {
-                struct net_device *dev;
+        for (addr = cb->args[0]; addr < 64; addr++) {
+                struct net_device *dev = phonet_route_get_rcu(net, addr << 2);
 
-                dev = phonet_route_get_rcu(net, addr << 2);
                 if (!dev)
                         continue;
 
-                if (addr_idx++ < addr_start_idx)
-                        continue;
-                fill_route(skb, dev, addr << 2, NETLINK_CB(cb->skb).portid,
-                           cb->nlh->nlmsg_seq, RTM_NEWROUTE);
-                /* fill_route() used to return > 0 (or negative errors) but
-                 * never 0 - ignore the return value and just go out to
-                 * call dumpit again from outside to preserve the behavior
-                 */
-                goto out;
+                if (fill_route(skb, dev, addr << 2, NETLINK_CB(cb->skb).portid,
+                               cb->nlh->nlmsg_seq, RTM_NEWROUTE) < 0)
+                        goto out;
         }
 
 out:
         rcu_read_unlock();
-        cb->args[0] = addr_idx;
-        cb->args[1] = 0;
+        cb->args[0] = addr;
 
         return skb->len;
 }