From: miod <miod@openbsd.org>
Date: Thu, 26 Dec 2013 21:02:37 +0000 (+0000)
Subject: When running the ll/sc version of the mutex code (for MULTIPROCESSOR kernels),
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=25b8a2fa4c529245454d4dc801b24c234aa8730b;p=openbsd

When running the ll/sc version of the mutex code (for MULTIPROCESSOR kernels),
correctly handle sc failures. All other ll/sc constructs were doing this
correctly but apparently noone had noticed mutex did not.
---

diff --git a/sys/arch/octeon/octeon/mutex.c b/sys/arch/octeon/octeon/mutex.c
index 2026a6088e3..8876a5edd66 100644
--- a/sys/arch/octeon/octeon/mutex.c
+++ b/sys/arch/octeon/octeon/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.5 2011/04/21 04:34:12 miod Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.6 2013/12/26 21:02:37 miod Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -39,12 +39,15 @@ try_lock(struct mutex *mtx)
 
         asm volatile (
 		".set noreorder\n"
-		"ll	%0, %2\n"
-		"bnez	%0, 1f\n"
-		"nop\n"
-		"li	%1, 1\n"
-		"sc	%1, %2\n"
 		"1:\n"
+		"ll	%0, %2\n"		/* tmp = mtx->mtx_lock */
+		"bnez	%0, 2f\n"
+		" li	%1, 0\n"		/* ret = 0 */
+		"li	%1, 1\n"		/* ret = 1 */
+		"sc	%1, %2\n"		/* mtx->mtx_lock = 1 */
+		"beqz	%1, 1b\n"		/* update failed */
+		" nop\n"
+		"2:\n"
 		".set reorder\n"
 		: "+r"(tmp), "+r"(ret)
 		: "m"(mtx->mtx_lock));
diff --git a/sys/arch/sgi/sgi/mutex.c b/sys/arch/sgi/sgi/mutex.c
index 2c85fa89e19..3fa43dac71c 100644
--- a/sys/arch/sgi/sgi/mutex.c
+++ b/sys/arch/sgi/sgi/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.12 2011/04/21 04:34:12 miod Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.13 2013/12/26 21:02:37 miod Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -39,12 +39,15 @@ try_lock(struct mutex *mtx)
 
         asm volatile (
 		".set noreorder\n"
-		"ll	%0, %2\n"
-		"bnez	%0, 1f\n"
-		"nop\n"
-		"li	%1, 1\n"
-		"sc	%1, %2\n"
 		"1:\n"
+		"ll	%0, %2\n"		/* tmp = mtx->mtx_lock */
+		"bnez	%0, 2f\n"
+		" li	%1, 0\n"		/* ret = 0 */
+		"li	%1, 1\n"		/* ret = 1 */
+		"sc	%1, %2\n"		/* mtx->mtx_lock = 1 */
+		"beqz	%1, 1b\n"		/* update failed */
+		" nop\n"
+		"2:\n"
 		".set reorder\n"
 		: "+r"(tmp), "+r"(ret)
 		: "m"(mtx->mtx_lock));