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Re: PATCH: Fix ll/sc for mips

To: Hiroyuki Machida <machida@sm.sony.co.jp>
Subject: Re: PATCH: Fix ll/sc for mips
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Fri, 1 Feb 2002 12:50:48 +0100 (MET)
Cc: hjl@lucon.org, libc-alpha@sources.redhat.com, linux-mips@oss.sgi.com
In-reply-to: <20020201.123523.50041631.machida@sm.sony.co.jp>
Organization: Technical University of Gdansk
Sender: owner-linux-mips@oss.sgi.com
On Fri, 1 Feb 2002, Hiroyuki Machida wrote:

> > It will fail if *p is not same as oldval.
> 
> Please note that "sc" may fail even if nobody write the
> variable. (See P.211 "8.4.2 Load-Linked/Sotre-Conditional" of "See 
> MIPS RUN" for more detail.) 
> So, after your patch applied, compare_and_swap() may fail, even if
> *p is equal to oldval.

 That's exactly what I meant -- "sc" may fail to execute the store, while
"cmpxchgl" may not. 

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +


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