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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>
This commit is contained in:
Jakub Sitnicki 2017-08-09 17:39:12 +02:00 committed by David S. Miller
parent aa69ff9e9c
commit d0225784be
1 changed files with 2 additions and 4 deletions
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6
net/core/rtnetlink.c
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@ -1621,8 +1621,6 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
s_h = cb->args[0]; s_h = cb->args[0];
s_idx = cb->args[1]; s_idx = cb->args[1];
cb->seq = net->dev_base_seq;
/* A hack to preserve kernel<->userspace interface. /* A hack to preserve kernel<->userspace interface.
* The correct header is ifinfomsg. It is consistent with rtnl_getlink. * The correct header is ifinfomsg. It is consistent with rtnl_getlink.
* However, before Linux v3.9 the code here assumed rtgenmsg and that's * 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; goto out_err;
} }
nl_dump_check_consistent(cb, nlmsg_hdr(skb));
cont: cont:
idx++; idx++;
} }
@ -1679,6 +1675,8 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
out_err: out_err:
cb->args[1] = idx; cb->args[1] = idx;
cb->args[0] = h; cb->args[0] = h;
cb->seq = net->dev_base_seq;
nl_dump_check_consistent(cb, nlmsg_hdr(skb));
return err; return err;
} }