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Date: Sat, 6 Oct 2001 08:24:51 -0700
To: Thomas Hood <jdthood@mail.com>
From: Jonathan Lundell <jlundell@pobox.com>
Subject: Re: Question about rtc_lock
Cc: linux-kernel@vger.kernel.org
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At 10:40 AM -0400 2001-10-06, Thomas Hood wrote:
>On Sat, 2001-10-06 at 09:13, Alan Cox wrote:
>>  > No, but what if the rtc interrupts while the lock is held in this
>>  > bit of code?
>>
>>  Thats fine. It wont take the lock
>
>But the first line of irq_interrupt() is:
>    spin_lock (&rtc_lock);
>
>If one has a multi-processor machine, and CPUx is going through
>the bootflag code, which takes the rtc_lock, and that CPU is
>interrupted and enters rtc_interrupt(), which tries to take the
>rtc_lock, won't it deadlock?
>
>If not, then I'm missing some clue about how these spinlocks work.

rtc_interrupt(), you mean.

Even if there weren't current interrupt code doing CMOS accesses, it 
would seem prudent to assume that there might be eventually, the 
RTC/NVRAM being a multi-purpose shared resource.
-- 
/Jonathan Lundell.
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