linux-kernel - Re: Query on lock protection in random number driver

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Message-ID: <p73fxx4mxa1.fsf@bingen.suse.de>
Date:	Fri, 11 Jan 2008 12:12:06 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Nikanth Karthikesan <knikanth@...e.de>
Cc:	linux-kernel@...r.kernel.org, mpm@...enic.com
Subject: Re: Query on lock protection in random number driver

Nikanth Karthikesan <knikanth@...e.de> writes:
>
> Also the globals random_read_wakeup_thresh and
> random_write_wakeup_thresh are not at all protected by any locks! Why
> locks are not needed for these?

Reading variables sizeof <= native word size (32bit or 64bit depending
on architecture) is atomic by itself. This is not necessarily
guaranteed in ISO-C or POSIX threads, but Linux can assume that.

-Andi
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