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Message-ID: <3E70F450.40000@isoar.ca>
Date: Thu, 13 Mar 2003 16:12:48 -0500
From: "Andrew E. Mileski" <andrewm@isoar.ca>
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To: Ralph Siemsen <ralphs@netwinder.org>
Subject: [Fwd: Re: PATCH: Atomic mutex for ARM [#5018]]
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-- 
Andrew E. Mileski
Ottawa, Canada
http://isoar.ca/

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Message-ID: <3E53DFCB.1060208@isoar.ca>
Date: Wed, 19 Feb 2003 14:49:31 -0500
From: "Andrew E. Mileski" <andrewm@isoar.ca>
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To: Keith Bostic <bostic@abyssinian.sleepycat.com>
Subject: Re: PATCH: Atomic mutex for ARM [#5018]
References: <200302191710.h1JHAIN0037740@abyssinian.sleepycat.com>
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Keith Bostic wrote:
>>Recently I bitched to a colleague that the patch hadn't made it
>>into the mainline yet :)
> 
> Our mainline releases?  This change has been in our releases
> ever since you sent it to us, I believe.

Sorry,  The blame is Red Hat's.  They are still shipping 4.0.14.

> I'm concerned about the major change to MUTEX_UNSET -- why is
> that additional work needed?

Since I din't have the same source base as you, it was easier to
copy and paste 10 lines in the editor than type out 1 line <:)

> Our current code is as follows.  Do we really need the change
> to MUTEX_UNSET?

No.

> Can you send me a diff against the current code?

Attached.

> And, would you be able to run our mutex test code against a
> current Berkeley DB snapshot?  If so, please let me know and
> I'll point you to a snapshot and instructions for running the
> mutex test.

Sure.

-- 
Andrew E. Mileski
Ottawa, Canada
http://isoar.ca/

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--- db-4.1.25/dbinc/mutex.h.orig	2003-02-19 14:33:05.000000000 -0500
+++ db-4.1.25/dbinc/mutex.h	2003-02-19 14:37:17.000000000 -0500
@@ -398,10 +398,11 @@
  */
 #define	MUTEX_SET(tsl) ({						\
 	int __r;							\
-	asm volatile("swpb %0, %1, [%2]"				\
-	    : "=r" (__r) 						\
-	    : "0" (1), "r" (tsl)					\
-	    : "memory"							\
+	asm volatile(							\
+		"swpb	%0, %1, [%2]\n\t"				\
+		"eor	%0, %0, #1\n\t"					\
+	    : "=&r" (__r) 						\
+	    : "r" (1), "r" (tsl)					\
 	    );								\
 	__r & 1;							\
 })

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