linux-kernel - Re: [PATCH] tcp: splice as many packets as possible at once

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Date:	Sat, 10 Jan 2009 08:40:05 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Evgeniy Polyakov <zbr@...emap.net>
CC:	Willy Tarreau <w@....eu>, David Miller <davem@...emloft.net>,
	ben@...s.com, jarkao2@...il.com, mingo@...e.hu,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	jens.axboe@...cle.com
Subject: Re: [PATCH] tcp: splice as many packets as possible at once

Evgeniy Polyakov a écrit :
> On Fri, Jan 09, 2009 at 11:17:44PM +0100, Willy Tarreau (w@....eu) wrote:
>> However I'm OK for the !timeo before release_sock/lock_sock. I just
>> don't know if we can put the rest of the if above or not. I don't
>> know what changes we're supposed to collect by doing release_sock/
>> lock_sock before the if().
> 
> Not to interrupt the discussion, but for the clarification, that
> release_sock/lock_sock is used to process the backlog accumulated while
> socket was locked. And while dropping additional pair before the final
> release is ok, but moving this itself should be thought of twice.
> 

Hum... I just caught the release_sock(sk)/lock_sock(sk) done in skb_splice_bits()

So :

1) the release_sock/lock_sock done in tcp_splice_read() is not necessary
to process backlog. Its already done in skb_splice_bits()

2) If we loop in tcp_read_sock() calling skb_splice_bits() several times
then we should perform the following tests inside this loop ?

if (sk->sk_err || sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN) ||
   signal_pending(current)) break;

And removie them from tcp_splice_read() ?



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