netdev - Re: [net-next PATCH] bpf: sockmap update/simplify memory accounting scheme

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Message-ID: <b91b19a8-b60b-2483-e878-d1f1e2b8e501@fb.com>
Date:   Fri, 1 Sep 2017 12:25:57 -0700
From:   Alexei Starovoitov <ast@...com>
To:     John Fastabend <john.fastabend@...il.com>, <davem@...emloft.net>
CC:     <netdev@...r.kernel.org>, <daniel@...earbox.net>
Subject: Re: [net-next PATCH] bpf: sockmap update/simplify memory accounting
 scheme

On 9/1/17 11:29 AM, John Fastabend wrote:
> Instead of tracking wmem_queued and sk_mem_charge by incrementing
> in the verdict SK_REDIRECT paths and decrementing in the tx work
> path use skb_set_owner_w and sock_writeable helpers. This solves
> a few issues with the current code. First, in SK_REDIRECT inc on
> sk_wmem_queued and sk_mem_charge were being done without the peers
> sock lock being held. Under stress this can result in accounting
> errors when tx work and/or multiple verdict decisions are working
> on the peer psock.
>
> Additionally, this cleans up the code because we can rely on the
> default destructor to decrement memory accounting on kfree_skb. Also
> this will trigger sk_write_space when space becomes available on
> kfree_skb() which wasn't happening before and prevent __sk_free
> from being called until all in-flight packets are completed.
>
> Fixes: 174a79ff9515 ("bpf: sockmap with sk redirect support")
> Signed-off-by: John Fastabend <john.fastabend@...il.com>
> Acked-by: Daniel Borkmann <daniel@...earbox.net>

thanks. it's cleaner indeed.

Acked-by: Alexei Starovoitov <ast@...nel.org>