MP safe mutex.

ok miod@

2 files changed, 52 insertions, 17 deletions

diff --git a/sys/arch/sgi/include/mutex.h b/sys/arch/sgi/include/mutex.h
index df505d80ba8..1d84c23882d 100644
--- a/sys/arch/sgi/include/mutex.h
+++ b/sys/arch/sgi/include/mutex.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.h,v 1.4 2009/10/22 22:08:54 miod Exp $	*/
+/*	$OpenBSD: mutex.h,v 1.5 2009/11/04 02:26:24 syuu Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -35,6 +35,7 @@ struct mutex {
 	int mtx_lock;
 	int mtx_wantipl;
 	int mtx_oldipl;
+	void *mtx_owner;
 };
 
 void mtx_init(struct mutex *, int);
diff --git a/sys/arch/sgi/sgi/mutex.c b/sys/arch/sgi/sgi/mutex.c
index 9b431010b5b..03b3aa0389c 100644
--- a/sys/arch/sgi/sgi/mutex.c
+++ b/sys/arch/sgi/sgi/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.7 2009/10/22 22:08:54 miod Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.8 2009/11/04 02:26:24 syuu Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -31,14 +31,31 @@
 
 #include <machine/intr.h>
 
+static inline int
+try_lock(struct mutex *mtx)
+{
 #ifdef MULTIPROCESSOR
-#error This code needs more work
-#endif
+	int tmp, ret = 0;
+
+        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"
+		".set reorder\n"
+		: "+r"(tmp), "+r"(ret)
+		: "m"(mtx->mtx_lock));
+	
+	return ret;
+#else  /* MULTIPROCESSOR */
+	mtx->mtx_lock = 1;
+	return 1;
+#endif /* MULTIPROCESSOR */
+}
 
-/*
- * Single processor systems don't need any mutexes, but they need the spl
- * raising semantics of the mutexes.
- */
 void
 mtx_init(struct mutex *mtx, int wantipl)
 {
@@ -50,22 +67,38 @@ mtx_init(struct mutex *mtx, int wantipl)
 void
 mtx_enter(struct mutex *mtx)
 {
-	if (mtx->mtx_wantipl != IPL_NONE)
-		mtx->mtx_oldipl = splraise(mtx->mtx_wantipl);
+	int s;
 
-	MUTEX_ASSERT_UNLOCKED(mtx);
-	mtx->mtx_lock = 1;
+	for (;;) {
+		if (mtx->mtx_wantipl != IPL_NONE)
+			s = splraise(mtx->mtx_wantipl);
+		if (try_lock(mtx)) {
+			if (mtx->mtx_wantipl != IPL_NONE)
+				mtx->mtx_oldipl = s;
+			mtx->mtx_owner = curcpu();
+			return;
+		}
+		if (mtx->mtx_wantipl != IPL_NONE)
+			splx(s);
+	}
 }
 
 int
 mtx_enter_try(struct mutex *mtx)
 {
+	int s;
+	
+ 	if (mtx->mtx_wantipl != IPL_NONE)
+		s = splraise(mtx->mtx_wantipl);
+	if (try_lock(mtx)) {
+		if (mtx->mtx_wantipl != IPL_NONE)
+			mtx->mtx_oldipl = s;
+		mtx->mtx_owner = curcpu();
+		return 1;
+	}
 	if (mtx->mtx_wantipl != IPL_NONE)
-		mtx->mtx_oldipl = splraise(mtx->mtx_wantipl);
-	MUTEX_ASSERT_UNLOCKED(mtx);
-	mtx->mtx_lock = 1;
-
-	return 1;
+		splx(s);
+	return 0;
 }
 
 void
@@ -75,4 +108,5 @@ mtx_leave(struct mutex *mtx)
 	mtx->mtx_lock = 0;
 	if (mtx->mtx_wantipl != IPL_NONE)
 		splx(mtx->mtx_oldipl);
+	mtx->mtx_owner = NULL;
 }