From: Matt Mackall <mpm@selenic.com>
To: andyliu <liudeyan@gmail.com>
Cc: linux-kernel@vger.kernel.org, tytso@mit.edu
Subject: Re: Concurrent access to /dev/urandom
Date: Wed, 8 Dec 2004 20:55:32 -0800 [thread overview]
Message-ID: <20041209045532.GC12189@waste.org> (raw)
In-Reply-To: <aad1205e0412081846161b4dcd@mail.gmail.com>
On Thu, Dec 09, 2004 at 10:46:30AM +0800, andyliu wrote:
> hi Ted
>
> i think this is better than use the spin lock.
> but i think maybe there should put an #ifdef SMP :)
> just like
>
> #ifdef CONFIG_SMP
> tmp[0] = 0x67452301 ^ smp_processor_id();
> tmp[1] = 0xefcdab89 ^ (__u32) current;
> tmp[2] = 0x98badcfe ^ preempt_count();
> #endif
>
> is it needed?
The race can be hit with get_random_bytes on UP if we get
interrupted/preempted between hashing and mixing. Which is why
preempt_count is useful..
--
Mathematics is the supreme nostalgia of our time.
next prev parent reply other threads:[~2004-12-09 4:55 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-27 20:45 Concurrent access to /dev/urandom Bernard Normier
2004-11-27 20:56 ` Jan Engelhardt
2004-11-27 21:15 ` Bernard Normier
2004-11-27 21:22 ` Jan Engelhardt
2004-11-28 20:58 ` Bernard Normier
2004-12-07 23:41 ` Bernard Normier
2004-12-08 1:28 ` Theodore Ts'o
2004-12-08 1:56 ` Bernard Normier
2004-12-08 19:21 ` Theodore Ts'o
2004-12-08 20:15 ` Bernard Normier
2004-12-08 21:56 ` Matt Mackall
2004-12-09 1:57 ` Theodore Ts'o
2004-12-09 2:46 ` andyliu
2004-12-09 4:55 ` Matt Mackall [this message]
2004-12-09 2:58 ` Matt Mackall
2004-12-09 21:29 ` Matt Mackall
2004-12-10 4:47 ` Matt Mackall
2004-12-10 16:35 ` Theodore Ts'o
2004-12-10 18:28 ` Matt Mackall
2004-12-10 21:28 ` Theodore Ts'o
2004-12-10 22:23 ` Matt Mackall
2004-12-11 0:22 ` Adam Heath
2004-12-11 1:10 ` Matt Mackall
2004-12-11 17:33 ` Theodore Ts'o
2004-12-11 19:58 ` Adam Heath
2004-12-11 20:40 ` Matt Mackall
2004-12-12 16:19 ` Pavel Machek
2004-12-11 0:19 ` Adam Heath
2004-12-09 3:10 ` David Lang
2004-12-09 4:52 ` Matt Mackall
2004-12-09 6:36 ` Theodore Ts'o
2004-11-29 22:47 ` Jon Masters
2004-11-29 23:14 ` Bernard Normier
2004-11-29 23:43 ` Sven-Haegar Koch
2004-11-30 2:31 ` David Schwartz
2004-11-30 4:14 ` Kyle Moffett
2004-11-30 8:23 ` Jan Engelhardt
2004-11-30 18:50 ` David Schwartz
2004-11-29 23:42 ` David Wagner
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