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From: Dan Kegel <dank@kegel.com>
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	davem@davemloft.net
Subject: Re: UDP recvmsg blocks after select(), 2.6 bug?
Date: Wed, 06 Oct 2004 08:30:19 -0700	[thread overview]
Message-ID: <41640F8B.8060009@kegel.com> (raw)

David S. Miller wrote:
> Incorrect UDP checksums could cause the read data to
> be discarded.  We do the copy into userspace and checksum
> computation in parallel.  This is totally legal and we've
> been doing it since 2.4.x first got released.

Might there be a similar effect for packets with bad IP or TCP checksums?
(http://citeseer.ist.psu.edu/stone00when.html)

And as Bert says, Stevens mentions that with TCP accepts,
the other side might close before you call accept.

BTW this is why I insisted in JSR-51 that Java's NIO not allow
the use of Selector with blocking sockets:

http://java.sun.com/j2se/1.4.2/docs/api/java/nio/channels/SelectableChannel.html
"A channel must be placed into non-blocking mode before being
registered with a selector, and may not be returned to blocking mode until it has been deregistered."

So at least Java programs that use NIO are immune to this
particular user error (unless your implementation of NIO
relaxes this sanity check, tsk).

- Dan

-- 
My technical stuff: http://kegel.com
My politics: see http://www.misleader.org for examples of why I'm for regime change

             reply	other threads:[~2004-10-06 16:46 UTC|newest]

Thread overview: 183+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-10-06 15:30 Dan Kegel [this message]
  -- strict thread matches above, loose matches on Subject: below --
2004-10-19  1:21 UDP recvmsg blocks after select(), 2.6 bug? 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
2004-10-07  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
2004-10-06 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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