bpf.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: John Fastabend <john.fastabend@gmail.com>
To: Jakub Sitnicki <jakub@cloudflare.com>,
	John Fastabend <john.fastabend@gmail.com>
Cc: daniel@iogearbox.net, xiyou.wangcong@gmail.com,
	alexei.starovoitov@gmail.com, bpf@vger.kernel.org,
	netdev@vger.kernel.org
Subject: Re: [PATCH bpf 1/3] bpf, sockmap: zap ingress queues after stopping strparser
Date: Tue, 20 Jul 2021 10:41:27 -0700	[thread overview]
Message-ID: <60f70ac727c2d_6600820855@john-XPS-13-9370.notmuch> (raw)
In-Reply-To: <87v955qnzp.fsf@cloudflare.com>

Jakub Sitnicki wrote:
> On Mon, Jul 19, 2021 at 11:48 PM CEST, John Fastabend wrote:
> > We don't want strparser to run and pass skbs into skmsg handlers when
> > the psock is null. We just sk_drop them in this case. When removing
> > a live socket from map it means extra drops that we do not need to
> > incur. Move the zap below strparser close to avoid this condition.
> >
> > This way we stop the stream parser first stopping it from processing
> > packets and then delete the psock.
> >
> > Fixes: a136678c0bdbb ("bpf: sk_msg, zap ingress queue on psock down")
> > Signed-off-by: John Fastabend <john.fastabend@gmail.com>
> > ---
> 
> To confirm my understanding - the extra drops can happen because
> currently we are racing to clear SK_PSOCK_TX_ENABLED flag in
> sk_psock_drop with sk_psock_verdict_apply, which checks the flag before
> pushing skb onto psock->ingress_skb queue (or possibly straight into
> psock->ingress_msg queue on no redirect).


Correct. If strparser hands a skb to the sk_psock_* handlers then before
they enqueue the packet the flag is checked and the packet will be
dropped in this case. I noticed this while testing. So rather than
letting packets get into sk_psock_* handlers this patch just stops the
strparser.

  reply	other threads:[~2021-07-20 17:41 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-19 21:48 [PATCH bpf 0/3] sockmap fixes picked up by stress tests John Fastabend
2021-07-19 21:48 ` [PATCH bpf 1/3] bpf, sockmap: zap ingress queues after stopping strparser John Fastabend
2021-07-20 10:27   ` Jakub Sitnicki
2021-07-20 17:41     ` John Fastabend [this message]
2021-07-19 21:48 ` [PATCH bpf 2/3] bpf, sockmap: on cleanup we additionally need to remove cached skb John Fastabend
2021-07-21  9:38   ` Dan Carpenter
2021-07-21 10:13   ` Jakub Sitnicki
2021-07-19 21:48 ` [PATCH bpf 3/3] bpf, sockmap: fix memleak on ingress msg enqueue John Fastabend
2021-07-21 16:36   ` Jakub Sitnicki
2021-07-21 18:02   ` Martin KaFai Lau
2021-07-21 16:38 ` [PATCH bpf 0/3] sockmap fixes picked up by stress tests Jakub Sitnicki

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=60f70ac727c2d_6600820855@john-XPS-13-9370.notmuch \
    --to=john.fastabend@gmail.com \
    --cc=alexei.starovoitov@gmail.com \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=jakub@cloudflare.com \
    --cc=netdev@vger.kernel.org \
    --cc=xiyou.wangcong@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).