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Date: Fri, 13 Feb 2004 13:34:45 -0800
From: Tim Hockin <thockin@hockin.org>
To: RANDAZZO@ddc-web.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: FW: spinlocks dont work
Message-ID: <20040213213445.GA23759@hockin.org>
References: <89760D3F308BD41183B000508BAFAC4104B16F74@DDCNYNTD>
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On Fri, Feb 13, 2004 at 04:12:08PM -0500, RANDAZZO@ddc-web.com wrote:
> On a uniprocessor system, with config_smp NOT Defined...
> 
> Note the following example:
> 
> driver 'A' calls spin_lock_irqsave and gets through (but does not call
> ..unlock).
> driver 'B' calls spin_lock_irqsave and gets through???
> 
> How can B get through if A did not unlock yet?

Because actual mutexing is a no-op without CONFIG_SMP.  What you have is a BUG.
Don't do that.