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Date: Wed, 29 Aug 2007 14:40:50 -0700
From: Wolfgang Reissnegger <wolfgang.reissnegger@xilinx.com>
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To: melinda develey <melinda.develey70@yahoo.com>
Subject: Re: spin_lock doesn't work?!?
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Hi Melinda,

depending on how your kernel is configured spin_locks will compileinto
nothing. For example, if you are compiling a kernel for a single
processor platform without preemptive scheduling then the spin_lock()
calls will be compiled into no-op as they are unnecessary on a non-SMP,
non-preemptive system.

You should still put the spin_lock calls into your code because you
never know if someone else will compile it and for another target. If
someone would, for example, compile the same code for a SMP machine then
the spin_lock will actually lock.

Cheers,
   Wolfgang

melinda develey wrote:
> I discovered that I called spin_lock two times consecutively without
> calling spin_unlock but my code didn't lock (I was managing an ioctl).
> Probably I didn't understand how spin_lock works!!!!
> 
> Any help?
> 
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