Commit d0225784 authored Aug 09, 2017 by Jakub Sitnicki Committed by David S. Miller Aug 13, 2017

rtnelink: Move link dump consistency check out of the loop



Calls to rtnl_dump_ifinfo() are protected by RTNL lock. So are the
{list,unlist}_netdevice() calls where we bump the net->dev_base_seq
number.

For this reason net->dev_base_seq can't change under out feet while
we're looping over links in rtnl_dump_ifinfo(). So move the check for
net->dev_base_seq change (since the last time we were called) out of the
loop.

This way we avoid giving a wrong impression that there are concurrent
updates to the link list going on while we're iterating over them.

Signed-off-by: Jakub Sitnicki <jkbs@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent aa69ff9e

net/core/rtnetlink.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -1621,8 +1621,6 @@ static int rtnl_dump_ifinfo(struct sk_buff skb, struct netlink_callback cb)
		s_h = cb->args[0];
		s_idx = cb->args[1];

		cb->seq = net->dev_base_seq;

		/* A hack to preserve kernel<->userspace interface.
		* The correct header is ifinfomsg. It is consistent with rtnl_getlink.
		* However, before Linux v3.9 the code here assumed rtgenmsg and that's
		@@ -1668,8 +1666,6 @@ static int rtnl_dump_ifinfo(struct sk_buff skb, struct netlink_callback cb)

		goto out_err;
		}

		nl_dump_check_consistent(cb, nlmsg_hdr(skb));
		cont:
		idx++;
		}
		@@ -1679,6 +1675,8 @@ out:
		out_err:
		cb->args[1] = idx;
		cb->args[0] = h;
		cb->seq = net->dev_base_seq;
		nl_dump_check_consistent(cb, nlmsg_hdr(skb));

		return err;
		}

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