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From: Keith Whitwell <keith@tungstengraphics.com>
To: george anzinger <george@mvista.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: linux-2.5.18: DRM + cmpxchg issues
Date: Wed, 29 May 2002 08:23:27 +0100	[thread overview]
Message-ID: <3CF481EF.9010106@tungstengraphics.com> (raw)
In-Reply-To: <3CF33C10.1090302@tungstengraphics.com> <3CF427E4.79042F@mvista.com>

george anzinger wrote:
> Keith Whitwell wrote:
> 
>>Adam,
>>
>>I expect the answer is that we need to dig out the old one.
>>
>>Previously I don't think the full cmpxchg semantics werere required unless the
>>box is smp -- there's no case where atomic operations are required for
>>hardware interaction, for example.  ...
>>
>>Probably this changed with preempt, though, so we need one even on UP boxes...
>>
>>
> I can not think of any reason to need a lock or atomic
> operation because of preempt.  Even the management of the
> preempt on/off flags at most requires memory barriers, even
> in SMP boxen.  Do you have an example?

No, I was just pointing out grey areas in my own knowledge.

Keith


  reply	other threads:[~2002-05-29  7:24 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-05-28  8:13 linux-2.5.18: DRM + cmpxchg issues Keith Whitwell
2002-05-29  0:59 ` george anzinger
2002-05-29  7:23   ` Keith Whitwell [this message]
  -- strict thread matches above, loose matches on Subject: below --
2002-05-26  8:32 Adam J. Richter

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