netdev - Splice on blocking TCP sockets again..

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Message-ID: <20090930004820.GC19540@obsidianresearch.com>
Date:	Tue, 29 Sep 2009 18:48:20 -0600
From:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:	Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org
Cc:	"David S. Miller" <davem@...emloft.net>,
	Volker Lendecke <vl@...ba.org>
Subject: Splice on blocking TCP sockets again..

Eric,

I saw your patch from January regarding splicing on blocking sockets,
and I wondered what ever happened to it?

http://lkml.org/lkml/2009/1/13/507

It doesn't look like it has been applied.. I see the patch thread died
at davem's comments?

I have run into exactly the same problem as Samba, where I'd like the
TCP socket to be blocking, and the pipe to be non blocking ...

As it stands, 
  splice(socket,0,pipe,0,128*1024,SPLICE_F_MOVE); 
causes a random endless block and
  splice(socket,0,pipe,0,128*1024,SPLICE_F_MOVE | SPLICE_F_NONBLOCK);
will return 0 immediately if the TCP buffer is empty.

FWIW, it looks like samba has a splice code now, but doesn't enable it
due to this issue?

http://git.samba.org/?p=samba.git;a=history;f=source3/lib/recvfile.c;h=ea0159642137390a0f7e57a123684e6e63e47581;hb=HEAD

Thanks,
Jason
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