Date: Fri, 29 Aug 2008 13:02:58 -0400 (EDT)
From: Steven Rostedt <rostedt@goodmis.org>
To: Stephen Hemminger <shemminger@vyatta.com>
cc: Gregory Haskins <ghaskins@novell.com>, mingo@elte.hu, tglx@linutronix.de,
       linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
       gregory.haskins@gmail.com
Subject: Re: [ RT PATCH] seqlock: serialize against writers
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References: <20080829154237.1196.66825.stgit@dev.haskins.net> <20080829095729.0966d38e@extreme>
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/me adds "RT" to subject.

On Fri, 29 Aug 2008, Stephen Hemminger wrote:
> 
> I have mixed feelings about this. The point of this primitive was for
> cases where write contention was rare and writers only did small updates.
> So what you did was fix the primitive for cases where it is being misused.
> Do you have a real example where this is a problem? If so then the
> user of seqlock should be fixed, rather than fixing seqlock.
> 


I think there's some confusion here, because of the changes to raw. The 
raw_seqlock_t and mainline seqlock_t has no issue, and should not be 
touched.

What Gregory is solving is an issue in -rt where we let write seqlocks be 
preempted.  Thus this causes issues with determinism. This is a special 
case for -rt, and -rt only. It should not affect mainline in anyway.

Sorry for the noise.

-- Steve

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