From: "Martijn Sipkema" <msipkema@sipkema-digital.com>
To: "Adam Heath" <doogie@debian.org>
Cc: "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: UDP recvmsg blocks after select(), 2.6 bug?
Date: Thu, 7 Oct 2004 12:29:06 +0100 [thread overview]
Message-ID: <000401c4ac60$db477df0$161b14ac@boromir> (raw)
In-Reply-To: Pine.LNX.4.58.0410070506400.1194@gradall.private.brainfood.com
From: "Adam Heath" <doogie@debian.org>
Sent: Thursday, October 07, 2004 11:07
> On Thu, 7 Oct 2004, Martijn Sipkema wrote:
>
> > > > It does not matter - this behaviour should not be depended upon. There are
> > > > lots of other reasons why a packet might in fact not be available, kernels
> > > > are allowed to drop UDP packets at will.
> > >
> > > I've been lurking and reading this thread with great interest. I had been
> > > leaning towards thinking the kernel was wrong, until I read this email.
> > >
> > > This is a very excellent point.
> >
> > No, it isn't. If the kernel drops a UDP packet, select() should not return
> > indicating available data.
>
> The kernel can drop a packet after select() returns, and before read() is
> called. That's the whole point of *U*DP.
I don't think that is the point of UDP and I don't think the kernel should
do that, but there are two options for handling this:
If recvmsg() blocks until valid data is available then so should select().
If recvmsg() returns an error on invalid data then select() would indicate the
socket() as ready without knowing if the data was valid.
--ms
next prev parent reply other threads:[~2004-10-07 10:28 UTC|newest]
Thread overview: 183+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-07 4:50 UDP recvmsg blocks after select(), 2.6 bug? Dan Kegel
2004-10-07 8:04 ` bert hubert
2004-10-07 8:28 ` Adam Heath
2004-10-07 10:38 ` Martijn Sipkema
2004-10-07 10:07 ` Adam Heath
2004-10-07 11:29 ` Martijn Sipkema [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-10-19 1:21 John Pearson
2004-10-19 13:50 ` Colin Phipps
[not found] <fa.haprsoi.8k8kbk@ifi.uio.no>
[not found] ` <fa.isqjio8.ok2coo@ifi.uio.no>
2004-10-09 13:24 ` Bodo Eggert
2004-10-07 18:16 linux
2004-10-09 12:07 ` Colin Phipps
2004-10-06 15:30 Dan Kegel
2004-10-06 14:52 Joris van Rantwijk
2004-10-06 15:01 ` David S. Miller
2004-10-06 15:13 ` Chris Friesen
2004-10-06 15:15 ` Richard B. Johnson
2004-10-06 15:21 ` David S. Miller
2004-10-06 15:29 ` Richard B. Johnson
2004-10-06 15:42 ` David S. Miller
2004-10-06 15:57 ` Chris Friesen
2004-10-06 15:44 ` Lars Marowsky-Bree
2004-10-07 1:16 ` Paul Jakma
2004-10-07 7:10 ` Chris Friesen
2004-10-07 11:53 ` Paul Jakma
2004-10-07 13:32 ` Martijn Sipkema
2004-10-07 12:53 ` Paul Jakma
2004-10-07 13:12 ` Richard B. Johnson
2004-10-07 14:07 ` Martijn Sipkema
2004-10-07 13:19 ` Paul Jakma
2004-10-07 13:36 ` Paul Jakma
2004-10-07 15:01 ` Jean-Sebastien Trottier
2004-10-07 16:20 ` Chris Friesen
2004-10-07 18:20 ` Hua Zhong
2004-10-07 18:33 ` Chris Friesen
2004-10-07 22:41 ` Martijn Sipkema
2004-10-07 21:49 ` Chris Friesen
2004-10-07 22:00 ` David S. Miller
2004-10-07 22:24 ` Chris Friesen
2004-10-07 22:26 ` David S. Miller
2004-10-07 22:39 ` Chris Friesen
2004-10-07 22:42 ` David S. Miller
2004-10-07 23:27 ` Chris Friesen
2004-10-08 0:04 ` Ben Greear
2004-10-08 2:51 ` Mark Mielke
2004-10-08 3:39 ` David S. Miller
2004-10-08 3:48 ` Mark Mielke
2004-10-08 3:59 ` David S. Miller
2004-10-07 23:19 ` Martijn Sipkema
2004-10-07 22:24 ` David S. Miller
2004-10-07 22:33 ` Alan Curry
2004-10-07 22:42 ` Mark Mielke
2004-10-07 22:47 ` David S. Miller
2004-10-07 23:00 ` Mark Mielke
2004-10-07 23:07 ` David S. Miller
2004-10-08 6:10 ` Theodore Ts'o
2004-10-08 15:20 ` Mark Mielke
2004-10-08 0:37 ` Lee Revell
2004-10-07 22:46 ` Hua Zhong
2004-10-07 22:48 ` David S. Miller
2004-10-07 23:17 ` Martijn Sipkema
2004-10-07 13:45 ` Alan Cox
2004-10-07 16:32 ` Martijn Sipkema
2004-10-07 14:50 ` Alan Cox
2004-10-07 13:48 ` Alan Cox
2004-10-07 14:57 ` Richard B. Johnson
2004-10-07 15:18 ` Adam Heath
2004-10-07 16:39 ` Martijn Sipkema
2004-10-07 16:09 ` Mark Mielke
2004-10-07 17:18 ` Chris Friesen
2004-10-06 15:31 ` Chris Friesen
2004-10-06 15:41 ` David S. Miller
2004-10-06 16:07 ` Richard B. Johnson
2004-10-06 16:57 ` Neil Horman
2004-10-06 15:59 ` Paul Jackson
2004-10-06 16:35 ` Martijn Sipkema
2004-10-06 15:30 ` Chris Friesen
2004-10-06 15:09 ` Richard B. Johnson
2004-10-06 15:18 ` bert hubert
2004-10-06 16:41 ` Alan Cox
2004-10-06 18:04 ` Joris van Rantwijk
2004-10-06 19:30 ` Andries Brouwer
2004-10-06 19:23 ` Alan Cox
2004-10-06 22:08 ` Martijn Sipkema
2004-10-06 20:25 ` Alan Cox
2004-10-06 22:15 ` Andries Brouwer
2004-10-06 22:32 ` David S. Miller
2004-10-06 23:25 ` YOSHIFUJI Hideaki / 吉藤英明
2004-10-06 23:11 ` Willy Tarreau
2004-10-06 19:43 ` Hua Zhong
2004-10-06 19:54 ` Chris Friesen
2004-10-06 19:59 ` Hua Zhong
2004-10-06 20:10 ` Chris Friesen
2004-10-06 21:45 ` Martijn Sipkema
2004-10-06 23:35 ` David S. Miller
2004-10-06 20:06 ` David S. Miller
2004-10-06 20:18 ` Chris Friesen
2004-10-06 20:26 ` Hua Zhong
2004-10-06 20:38 ` Andries Brouwer
2004-10-06 20:58 ` Joris van Rantwijk
2004-10-06 22:29 ` David S. Miller
2004-10-07 16:08 ` Adrian Phillips
2004-10-06 20:06 ` Olivier Galibert
2004-10-06 23:35 ` David S. Miller
2004-10-07 0:19 ` Olivier Galibert
2004-10-07 0:29 ` David S. Miller
2004-10-07 10:56 ` Martijn Sipkema
2004-10-08 6:41 ` Willy Tarreau
2004-10-08 15:27 ` Mark Mielke
2004-10-15 22:42 ` Robert White
2004-10-15 23:33 ` David Schwartz
2004-10-16 0:59 ` Chris Friesen
2004-10-16 2:35 ` Mark Mielke
2004-10-16 4:23 ` David Schwartz
2004-10-16 4:35 ` Mark Mielke
2004-10-16 4:58 ` David Schwartz
2004-10-16 6:25 ` Mark Mielke
2004-10-16 21:44 ` Roland Kuhn
2004-10-17 0:06 ` Mark Mielke
2004-10-17 0:30 ` David Schwartz
2004-10-17 14:47 ` Mark Mielke
2004-10-17 0:28 ` David Schwartz
2004-10-17 13:35 ` Lars Marowsky-Bree
2004-10-17 14:17 ` Buddy Lucas
2004-10-17 15:05 ` Mark Mielke
2004-10-17 15:40 ` Buddy Lucas
2004-10-17 16:13 ` Lee Revell
2004-10-17 17:35 ` Jesper Juhl
2004-10-17 18:04 ` Buddy Lucas
2004-10-17 18:06 ` Lars Marowsky-Bree
2004-10-17 18:21 ` Buddy Lucas
2004-10-17 20:04 ` Martijn Sipkema
2004-10-17 20:08 ` Lars Marowsky-Bree
2004-10-17 17:35 ` Martijn Sipkema
2004-10-17 17:33 ` Buddy Lucas
2004-10-17 19:58 ` Martijn Sipkema
2004-10-17 19:33 ` Buddy Lucas
2004-10-17 20:11 ` Lars Marowsky-Bree
2004-10-17 20:25 ` Buddy Lucas
2004-10-17 20:42 ` Martijn Sipkema
2004-10-17 20:02 ` Buddy Lucas
2004-10-17 18:53 ` David Schwartz
2004-10-17 19:26 ` Hua Zhong
2004-10-17 20:32 ` Martijn Sipkema
2004-10-17 19:21 ` Hua Zhong
2004-10-17 17:22 ` Lars Marowsky-Bree
2004-10-17 17:54 ` Buddy Lucas
2004-10-17 18:05 ` Lars Marowsky-Bree
2004-10-17 18:06 ` Mark Mielke
2004-10-20 21:31 ` H. Peter Anvin
2004-10-20 21:58 ` Chris Friesen
2004-10-20 22:00 ` H. Peter Anvin
2004-10-20 22:12 ` Chris Friesen
2004-10-20 23:16 ` David Schwartz
2004-10-21 1:03 ` Chris Friesen
2004-10-21 1:38 ` David Schwartz
2004-10-21 3:01 ` Michael Clark
2004-10-21 3:52 ` Michael Clark
2004-10-21 4:10 ` H. Peter Anvin
2004-10-21 5:06 ` Chris Friesen
2004-10-21 5:11 ` H. Peter Anvin
2004-10-21 5:50 ` Chris Friesen
2004-10-21 5:58 ` H. Peter Anvin
2004-10-21 15:18 ` Chris Friesen
2004-10-21 6:14 ` Michael Clark
2004-10-17 14:52 ` Mark Mielke
2004-10-16 18:25 ` Andries Brouwer
2004-10-17 0:28 ` David Schwartz
2004-10-17 12:22 ` Andries Brouwer
2004-10-16 10:24 ` Willy Tarreau
2004-10-16 13:21 ` Mark Mielke
2004-10-18 22:25 ` Robert White
2004-10-06 20:41 ` Neil Horman
2004-10-06 22:27 ` Chris Friesen
2004-10-06 23:32 ` Neil Horman
2004-10-06 23:36 ` David S. Miller
2004-10-07 19:31 ` David Schwartz
2004-10-07 22:36 ` Martijn Sipkema
2004-10-08 0:19 ` David Schwartz
2004-10-09 19:21 ` Martijn Sipkema
2004-10-09 18:28 ` David Schwartz
2004-10-09 18:49 ` Mark Mielke
2004-10-09 21:00 ` Martijn Sipkema
2004-10-09 22:59 ` Mark Mielke
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