On Thu, 7 Jul 2016, Eric Dumazet wrote:
> > @@ -1440,6 +1441,7 @@ static int tc_dump_qdisc_root(struct Qdisc *root,
> > struct sk_buff *skb,
> > {
> > int ret = 0, q_idx = *q_idx_p;
> > struct Qdisc *q;
> > + int b;
> >
> > if (!root)
> > return 0;
> > @@ -1454,7 +1456,7 @@ static int tc_dump_qdisc_root(struct Qdisc *root,
> > struct sk_buff *skb,
> > goto done;
> > q_idx++;
> > }
> > - list_for_each_entry(q, &root->list, list) {
> > + hash_for_each(qdisc_dev(root)->qdisc_hash, b, q, hash) {
> > if (q_idx < s_q_idx) {
> > q_idx++;
> > continue;
> > @@ -1771,6 +1773,7 @@ static int tc_dump_tclass_root(struct Qdisc *root,
> > struct sk_buff *skb,
> > int *t_p, int s_t)
> > {
> > struct Qdisc *q;
> > + int b;
> >
> > if (!root)
> > return 0;
> > @@ -1778,7 +1781,7 @@ static int tc_dump_tclass_root(struct Qdisc *root,
> > struct sk_buff *skb,
> > if (tc_dump_tclass_qdisc(root, skb, tcm, cb, t_p, s_t) < 0)
> > return -1;
> >
> > - list_for_each_entry(q, &root->list, list) {
> > + hash_for_each_rcu(qdisc_dev(root)->qdisc_hash, b, q, hash) {
> > if (tc_dump_tclass_qdisc(q, skb, tcm, cb, t_p, s_t) < 0)
> > return -1;
> > }
>
>
> Not sure why you used the rcu version here, but the non rcu version in
> tc_dump_qdisc_root()
Good catch.
Actually even the current code is odd in this regard --
qdisc_match_from_root() uses RCU iterator, while tc_dump_*() use the
non-RCU one; addition and deletion is performed using RCU primitives.
I haven't got my head around this yet; if it's correct at all, it'd at
least deserve a comment somewhere.
I'll respin v2 of the patch (there is also a conflict on HASH_SIZE
definition in ip6_tunnel.c, ip6_gre.c and sit.c due to hashtable.h include
in netdevice.h that needs to be resolved as well) that'd make RCU usage
consistent.
Any other objections/comments? I was namely curious about any opinions
regarding the hashtable size.
Thanks,
--
Jiri Kosina
SUSE Labs
