From: Sergei Shtylyov <sergei.shtylyov@cogentembedded•com>
To: Aaron Conole <aconole@bytheb•org>, netdev@vger•kernel.org
Subject: Re: [PATCH net] af_unix: return data from multiple SKBs on recv() with MSG_PEEK flag
Date: Sat, 19 Sep 2015 20:23:26 +0300 [thread overview]
Message-ID: <55FD9A0E.1090804@cogentembedded.com> (raw)
In-Reply-To: <f7tvbb7zpbf.fsf@aconole.bos.csb>
Hello.
On 9/18/2015 7:04 PM, Aaron Conole wrote:
> AF_UNIX sockets now return multiple skbs from recv() when MSG_PEEK flag
> is set.
>
> This is referenced in kernel bugzilla #12323 @
> https://bugzilla.kernel.org/show_bug.cgi?id=12323
>
> As described both in the BZ and lkml thread @
> http://lkml.org/lkml/2008/1/8/444 calling recv() with MSG_PEEK on an
> AF_UNIX socket only reads a single skb, where the desired effect is
> to return as much skb data has been queued, until hitting the recv
> buffer size (whichever comes first).
>
> The modified MSG_PEEK path will now move to the next skb in the tree
> and jump to the again: label, rather than following the natural loop
> structure. This requires duplicating some of the loop head actions.
>
> This was tested using the python socketpair() code attached to the
> bugzilla issue.
>
> Signed-off-by: Aaron Conole <aconole@bytheb•org>
Your patch doesn't comply to the Linux CodingStyle.
> ---
> net/unix/af_unix.c | 17+-
> 1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 03ee4d3..d2fd342 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -2179,9 +2181,22 @@ unlock:
> if (UNIXCB(skb).fp)
> scm.fp = scm_fp_dup(UNIXCB(skb).fp);
>
> - sk_peek_offset_fwd(sk, chunk);
> + if (skip)
> + {
if (skip) {
> + sk_peek_offset_fwd(sk, chunk);
> + skip -= chunk;
> + }
>
> - break;
> + if (UNIXCB(skb).fp)
> + break;
> +
> + /* XXX - this is ugly; better would be rewrite the function */
> + last = skb;
> + last_len = skb->len;
> + unix_state_lock(&sk);
> + skb = skb_peek_next(skb, &sk->sk_receive_queue);
> + if (skb) goto again;
if (skb)
goto again;
> + goto unlock;
> }
> } while (size);
>
MBR, Sergei
next prev parent reply other threads:[~2015-09-19 17:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-18 16:04 [PATCH net] af_unix: return data from multiple SKBs on recv() with MSG_PEEK flag Aaron Conole
2015-09-19 17:23 ` Sergei Shtylyov [this message]
2015-09-20 1:55 ` Aaron Conole
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