netdev - Re: Fwd: u32 ht filters

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Message-ID: <20180212155102.GC2153@nanopsycho>
Date:   Mon, 12 Feb 2018 16:51:02 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     Jiri Pirko <jiri@...lanox.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Paweł Staszewski <pstaszewski@...are.pl>
Subject: Re: Fwd: u32 ht filters

Mon, Feb 12, 2018 at 04:32:16PM CET, jiri@...nulli.us wrote:
>Sat, Feb 10, 2018 at 09:41:57PM CET, xiyou.wangcong@...il.com wrote:
>
>[...]
>
>>>>@@ -348,7 +340,7 @@ static struct tc_u_common *tc_u_common_find(const
>>>>struct tcf_proto *tp)
>>>>
>>>>        h = tc_u_hash(tp);
>>>>        hlist_for_each_entry(tc, &tc_u_common_hash[h], hnode) {
>>>>-               if (tc->block == tp->chain->block)
>>>>+               if (tc->block->q == tp->chain->block->q)
>>>
>>> :O I don't get it. tc->block is pointer, tc->block->q is pointer. And
>>> they are different at the same time for non-shared block.
>>
>>If you look into Pawel's script, a new block is created for each class
>>therefore a different tc_u_common is created which causes the
>>ht 9:22 can't be found.
>
>But wait. Originally this code looked like this:
>static unsigned int tc_u_hash(const struct tcf_proto *tp)
>{
>        struct net_device *dev = tp->q->dev_queue->dev;
>        u32 qhandle = tp->q->handle;
>        int ifindex = dev->ifindex;
>
>        return hash_64((u64)ifindex << 32 | qhandle, U32_HASH_SHIFT);
>}
>
>static struct tc_u_common *tc_u_common_find(const struct tcf_proto *tp)
>{
>        struct tc_u_common *tc;
>        unsigned int h;
>
>        h = tc_u_hash(tp);
>        hlist_for_each_entry(tc, &tc_u_common_hash[h], hnode) {
>                if (tc->q == tp->q)
>                        return tc;
>        }
>        return NULL;
>}
>
>That means that tc_u_common is identified according to tp->q. And that
>is different for every class. How that could work? I'm properly confused.

Okay, now I see what is wrong. I wrongly assumed 1:1 block:q. Will fix.