From: Jamie Lokier <jamie@shareable.org>
To: Timo Sirainen <tss@iki.fi>
Cc: root@chaos.analogic.com,
Martin Konold <martin.konold@erfrakon.de>,
linux-kernel@vger.kernel.org
Subject: Re: Lockless file reading
Date: Thu, 28 Aug 2003 07:13:33 +0100 [thread overview]
Message-ID: <20030828061333.GA5822@mail.jlokier.co.uk> (raw)
In-Reply-To: <3217CEE6-D906-11D7-A165-000393CC2E90@iki.fi>
Timo Sirainen wrote:
> I'm sure someone has figured out a way to make a checksum of data that
> can detect if there's even a single bit wrong, if the checksum is
> allowed to take as much space as the data itself. I should read more
> about algorithms..
You said that MD5 wasn't strong enough, and you would like a guarantee.
You won't find a guarantee unless you are prepared to use memory
barriers in your code. _Any_ checksum is going to have a chance of
false validation if you are doing out-of-order reads which can observe
parts of the old and new data, and parts of the old and new checksum.
> How about checksum[n] = data[n-1] ^ data[n]? That looks like it would
> work.
Consider when the data {1,0,1,0} is replaced by {2,0,2,0}.
-- Jamie
next prev parent reply other threads:[~2003-08-28 6:13 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-27 12:37 Timo Sirainen
2003-08-27 12:42 ` Martin Konold
2003-08-27 12:52 ` Timo Sirainen
2003-08-27 13:40 ` Richard B. Johnson
2003-08-27 14:56 ` Timo Sirainen
2003-08-27 23:39 ` Jamie Lokier
2003-08-28 0:52 ` Timo Sirainen
2003-08-27 18:42 ` Nagendra Singh Tomar
2003-08-28 8:40 ` Timo Sirainen
2003-08-27 21:15 ` Nagendra Singh Tomar
2003-08-28 9:35 ` Timo Sirainen
2003-08-27 21:52 ` Nagendra Singh Tomar
2003-08-28 13:26 ` Matthias Andree
2003-08-28 9:17 ` David Schwartz
2003-08-28 8:42 ` Valdis.Kletnieks
2003-08-28 20:13 ` David B. Stevens
2003-08-28 1:50 ` Jamie Lokier
2003-08-28 3:17 ` Timo Sirainen
2003-08-28 6:01 ` Valdis.Kletnieks
2003-08-28 6:13 ` Jamie Lokier [this message]
2003-08-28 8:57 ` Timo Sirainen
2003-08-28 9:56 ` David Schwartz
2003-08-28 10:26 ` Timo Sirainen
2003-08-27 22:58 ` Nagendra Singh Tomar
2003-08-28 12:18 ` Jamie Lokier
2003-08-28 0:39 ` Nagendra Singh Tomar
2003-08-28 13:00 ` Jamie Lokier
2003-08-28 1:06 ` Nagendra Singh Tomar
2003-08-28 21:49 ` Bernd Eckenfels
2003-08-28 12:01 ` Jamie Lokier
2003-08-28 13:28 ` Timo Sirainen
2003-08-28 20:24 ` David Schwartz
2003-08-28 12:44 ` Ragnar Hojland Espinosa
2003-08-28 13:03 ` Jamie Lokier
2003-08-28 17:26 ` root
2003-08-28 17:35 ` Jamie Lokier
2003-08-28 18:10 ` root
2003-08-28 21:59 ` Bernd Eckenfels
2003-08-28 23:02 ` Jamie Lokier
2003-08-28 23:44 ` Lockless file readingu root
2003-08-29 10:00 ` jlnance
2003-08-29 11:55 ` David Schwartz
2003-08-29 15:43 ` William Lee Irwin III
2003-08-28 20:37 ` Lockless file reading David Schwartz
2003-08-28 22:11 ` Bernd Eckenfels
2003-08-28 23:00 ` Jamie Lokier
2003-08-29 0:47 ` David Schwartz
2003-08-28 9:13 ` Martin Konold
2003-08-28 9:27 ` Timo Sirainen
2003-08-28 9:48 ` Martin Konold
2003-08-28 0:03 ` Jamie Lokier
2003-08-28 12:08 ` Richard B. Johnson
2003-08-28 12:39 ` Jamie Lokier
2003-08-28 10:08 ` Matthias Andree
2003-08-28 10:54 ` Robin Rosenberg
2003-08-28 12:42 ` Jamie Lokier
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