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

[David Miller <davem@davemloft.net>]

From: John Fastabend <john.fastabend@gmail.com>
Date: Fri, 01 Sep 2017 11:29:26 -0700

> 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@gmail.com>
> Acked-by: Daniel Borkmann <daniel@iogearbox.net>

Applied.