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Date: Thu, 3 Mar 2005 00:24:58 -0600
From: Alan Cox <alc@cs.rice.edu>
To: Doug White <dwhite@FreeBSD.org>
Message-ID: <20050303062458.GA15192@cs.rice.edu>
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Subject: Re: cvs commit: src/sys/kern uipc_mbuf.c
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On Thu, Mar 03, 2005 at 02:41:37AM +0000, Doug White wrote:
> dwhite      2005-03-03 02:41:37 UTC
> 
>   FreeBSD src repository
> 
>   Modified files:
>     sys/kern             uipc_mbuf.c 
>   Log:
>   Insert volatile cast to discourage gcc from optimizing the read outside
>   of the while loop.
>   
>   Suggested by:   alc
>   MFC after:      1 day
>   
>   Revision  Changes    Path
>   1.144     +4 -1      src/sys/kern/uipc_mbuf.c

I tend to believe that the sparc64's casa() implementation is the real
culprit here.  Specifically, I don't believe the right asm operand
constraints are being used.  If I'm correct, the addition of volatile
here is unnecessary.  Can we hold the MFC until this hypothesis is
proven or disproven?

Alan