netdev - Re: Fwd: u32 ht filters

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Message-ID: <20180212153216.GB2153@nanopsycho>
Date:   Mon, 12 Feb 2018 16:32:16 +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

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.