From: Willy Tarreau <willy@w.ods.org>
To: "David S. Miller" <davem@davemloft.net>
Cc: Olivier Galibert <galibert@pobox.com>, linux-kernel@vger.kernel.org
Subject: Re: UDP recvmsg blocks after select(), 2.6 bug?
Date: Fri, 8 Oct 2004 08:41:04 +0200 [thread overview]
Message-ID: <20041008064104.GF19761@alpha.home.local> (raw)
In-Reply-To: <20041006172959.47c25e3d.davem@davemloft.net>
Hi David,
On Wed, Oct 06, 2004 at 05:29:59PM -0700, David S. Miller wrote:
> It absolutely does help the programs not using select(), using
> blocking sockets, and not expecting -EAGAIN.
As I asked in a previous mail in this overly long thread, why not returning
zero bytes at all. It is perfectly valid to receive an UDP packet with 0
data bytes, and any application should be able to support this case anyway.
In case of TCP, this would be a problem because the app would think it
indicates the last byte has been received. But in case of UDP, there is no
problem.
BTW, could we enumerate the known cases where select() might report an FD
as readable while finally not ? If there are only very few cases which can
all be worked around at nearly no cost, it might be worth doing it, or at
least documenting them. From this thread, I gathered :
1) multi-threaded apps -> broken design anyway, and should be obvious.
at most, the case can be documented
2) bad UDP checksums -> this is currently the object of this thread
3) packet dropped because of buffer size, load, etc... (not confirmed)
4) others ? any TCP/unix socket/pipe known case ?
Regards,
Willy
next prev parent reply other threads:[~2004-10-08 6:41 UTC|newest]
Thread overview: 191+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-06 14:52 UDP recvmsg blocks after select(), 2.6 bug? 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 21:58 ` mmap specification - was: ... select specification Andries Brouwer
2004-10-07 22:17 ` Chris Wedgwood
2004-10-07 22:34 ` Andries Brouwer
2004-10-07 22:32 ` Kyle Moffett
2004-10-07 22:46 ` Andries Brouwer
2004-10-07 23:30 ` Kyle Moffett
2004-10-08 9:19 ` Andries Brouwer
2004-10-09 21:10 ` Martijn Sipkema
2004-10-07 13:48 ` UDP recvmsg blocks after select(), 2.6 bug? 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 [this message]
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
-- strict thread matches above, loose matches on Subject: below --
2004-10-06 15:30 Dan Kegel
2004-10-07 4:50 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
2004-10-07 18:16 linux
2004-10-09 12:07 ` 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
2004-10-19 1:21 John Pearson
2004-10-19 13:50 ` Colin Phipps
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