On Thu, Apr 28, 2016 at 07:13:44PM +0200, Florian Westphal wrote:
> The iteration process is lockless, so we test if the conntrack object is
> eligible for printing (e.g. is AF_INET) after obtaining the reference
> count.
>
> Once we put all conntracks into same hash table we might see more
> entries that need to be skipped.
>
> So add a helper and first perform the test in a lockless fashion
> for fast skip.
>
> Once we obtain the reference count, just repeat the check.
>
> Signed-off-by: Florian Westphal <f...@strlen.de>
> ---
> .../netfilter/nf_conntrack_l3proto_ipv4_compat.c | 24
> +++++++++++++++++-----
> 1 file changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
> b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
> index f0dfe92..483cf79 100644
> --- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
> +++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
> @@ -114,6 +114,19 @@ static inline void ct_show_secctx(struct seq_file *s,
> const struct nf_conn *ct)
> }
> #endif
>
> +static bool ct_seq_should_skip(const struct nf_conn *ct,
> + const struct nf_conntrack_tuple_hash *hash)
> +{
> + /* we only want to print DIR_ORIGINAL */
> + if (NF_CT_DIRECTION(hash))
> + return true;
> +
> + if (nf_ct_l3num(ct) != AF_INET)
> + return true;
> +
> + return false;
> +}
> +
> static int ct_seq_show(struct seq_file *s, void *v)
> {
> struct nf_conntrack_tuple_hash *hash = v;
> @@ -123,14 +136,15 @@ static int ct_seq_show(struct seq_file *s, void *v)
> int ret = 0;
>
> NF_CT_ASSERT(ct);
> - if (unlikely(!atomic_inc_not_zero(&ct->ct_general.use)))
> + if (ct_seq_should_skip(ct, hash))
> return 0;
>
> + if (unlikely(!atomic_inc_not_zero(&ct->ct_general.use)))
> + return 0;
>
> - /* we only want to print DIR_ORIGINAL */
> - if (NF_CT_DIRECTION(hash))
> - goto release;
> - if (nf_ct_l3num(ct) != AF_INET)
> + /* check if we raced w. object reuse */
> + if (!nf_ct_is_confirmed(ct) ||
This refactoring includes this new check, is this intentional?
> + ct_seq_should_skip(ct, hash))
> goto release;
>
> l3proto = __nf_ct_l3proto_find(nf_ct_l3num(ct));
> --
> 2.7.3
>
