patch-2.4.5 linux/include/asm-sparc64/semaphore.h

• Lines: 361
• Date: Sun May 20 11:32:08 2001
• Orig file: v2.4.4/linux/include/asm-sparc64/semaphore.h
• Orig date: Thu Apr 26 22:17:26 2001

diff -u --recursive --new-file v2.4.4/linux/include/asm-sparc64/semaphore.h linux/include/asm-sparc64/semaphore.h
@@ -1,52 +1,40 @@
 #ifndef _SPARC64_SEMAPHORE_H
 #define _SPARC64_SEMAPHORE_H
 
-/* These are actually reasonable on the V9. */
+/* These are actually reasonable on the V9.
+ *
+ * See asm-ppc/semaphore.h for implementation commentary,
+ * only sparc64 specific issues are commented here.
+ */
 #ifdef __KERNEL__
 
 #include <asm/atomic.h>
-#include <asm/bitops.h>
 #include <asm/system.h>
 #include <linux/wait.h>
 #include <linux/rwsem.h>
 
 struct semaphore {
 	atomic_t count;
-	atomic_t waking;
 	wait_queue_head_t wait;
-#if WAITQUEUE_DEBUG
-	long __magic;
-#endif
 };
 
-#if WAITQUEUE_DEBUG
-# define __SEM_DEBUG_INIT(name) \
-		, (long)&(name).__magic
-#else
-# define __SEM_DEBUG_INIT(name)
-#endif
-
-#define __SEMAPHORE_INITIALIZER(name,count) \
-{ ATOMIC_INIT(count), ATOMIC_INIT(0), __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
-	__SEM_DEBUG_INIT(name) }
+#define __SEMAPHORE_INITIALIZER(name, count) \
+	{ ATOMIC_INIT(count), \
+	  __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) }
 
 #define __MUTEX_INITIALIZER(name) \
-	__SEMAPHORE_INITIALIZER(name,1)
+	__SEMAPHORE_INITIALIZER(name, 1)
 
-#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
+#define __DECLARE_SEMAPHORE_GENERIC(name, count) \
 	struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
 
-#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
-#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
+#define DECLARE_MUTEX(name)		__DECLARE_SEMAPHORE_GENERIC(name, 1)
+#define DECLARE_MUTEX_LOCKED(name)	__DECLARE_SEMAPHORE_GENERIC(name, 0)
 
-extern inline void sema_init (struct semaphore *sem, int val)
+static inline void sema_init (struct semaphore *sem, int val)
 {
 	atomic_set(&sem->count, val);
-	atomic_set(&sem->waking, 0);
 	init_waitqueue_head(&sem->wait);
-#if WAITQUEUE_DEBUG
-	sem->__magic = (long)&sem->__magic;
-#endif
 }
 
 static inline void init_MUTEX (struct semaphore *sem)
@@ -61,143 +49,179 @@
 
 extern void __down(struct semaphore * sem);
 extern int  __down_interruptible(struct semaphore * sem);
-extern int  __down_trylock(struct semaphore * sem);
 extern void __up(struct semaphore * sem);
 
-extern __inline__ void down(struct semaphore * sem)
+static __inline__ void down(struct semaphore * sem)
 {
-#if WAITQUEUE_DEBUG
-	CHECK_MAGIC(sem->__magic);
-#endif
-	__asm__ __volatile__(
-"	1:	lduw	[%0], %%g5\n"
-"		sub	%%g5, 1, %%g7\n"
-"		cas	[%0], %%g5, %%g7\n"
-"		cmp	%%g5, %%g7\n"
-"		bne,pn	%%icc, 1b\n"
-"		 cmp	%%g7, 1\n"
-"		bl,pn	%%icc, 3f\n"
-"		 membar	#StoreStore\n"
-"	2:\n"
-"		.subsection 2\n"
-"	3:	mov	%0, %%g5\n"
-"		save	%%sp, -160, %%sp\n"
-"		mov	%%g1, %%l1\n"
-"		mov	%%g2, %%l2\n"
-"		mov	%%g3, %%l3\n"
-"		call	%1\n"
-"		 mov	%%g5, %%o0\n"
-"		mov	%%l1, %%g1\n"
-"		mov	%%l2, %%g2\n"
-"		ba,pt	%%xcc, 2b\n"
-"		 restore %%l3, %%g0, %%g3\n"
-"		.previous\n"
+	/* This atomically does:
+	 * 	old_val = sem->count;
+	 *	new_val = sem->count - 1;
+	 *	sem->count = new_val;
+	 *	if (old_val < 1)
+	 *		__down(sem);
+	 *
+	 * The (old_val < 1) test is equivalent to
+	 * the more straightforward (new_val < 0),
+	 * but it is easier to test the former because
+	 * of how the CAS instruction works.
+	 */
+
+	__asm__ __volatile__("\n"
+"	! down sem(%0)\n"
+"1:	lduw	[%0], %%g5\n"
+"	sub	%%g5, 1, %%g7\n"
+"	cas	[%0], %%g5, %%g7\n"
+"	cmp	%%g5, %%g7\n"
+"	bne,pn	%%icc, 1b\n"
+"	 cmp	%%g7, 1\n"
+"	bl,pn	%%icc, 3f\n"
+"	 membar	#StoreStore\n"
+"2:\n"
+"	.subsection 2\n"
+"3:	mov	%0, %%g5\n"
+"	save	%%sp, -160, %%sp\n"
+"	mov	%%g1, %%l1\n"
+"	mov	%%g2, %%l2\n"
+"	mov	%%g3, %%l3\n"
+"	call	%1\n"
+"	 mov	%%g5, %%o0\n"
+"	mov	%%l1, %%g1\n"
+"	mov	%%l2, %%g2\n"
+"	ba,pt	%%xcc, 2b\n"
+"	 restore %%l3, %%g0, %%g3\n"
+"	.previous\n"
 	: : "r" (sem), "i" (__down)
 	: "g5", "g7", "memory", "cc");
 }
 
-extern __inline__ int down_interruptible(struct semaphore *sem)
+static __inline__ int down_interruptible(struct semaphore *sem)
 {
 	int ret = 0;
 	
-#if WAITQUEUE_DEBUG
-	CHECK_MAGIC(sem->__magic);
-#endif
-	__asm__ __volatile__(
-"	1:	lduw	[%2], %%g5\n"
-"		sub	%%g5, 1, %%g7\n"
-"		cas	[%2], %%g5, %%g7\n"
-"		cmp	%%g5, %%g7\n"
-"		bne,pn	%%icc, 1b\n"
-"		 cmp	%%g7, 1\n"
-"		bl,pn	%%icc, 3f\n"
-"		 membar	#StoreStore\n"
-"	2:\n"
-"		.subsection 2\n"
-"	3:	mov	%2, %%g5\n"
-"		save	%%sp, -160, %%sp\n"
-"		mov	%%g1, %%l1\n"
-"		mov	%%g2, %%l2\n"
-"		mov	%%g3, %%l3\n"
-"		call	%3\n"
-"		 mov	%%g5, %%o0\n"
-"		mov	%%l1, %%g1\n"
-"		mov	%%l2, %%g2\n"
-"		mov	%%l3, %%g3\n"
-"		ba,pt	%%xcc, 2b\n"
-"		 restore %%o0, %%g0, %0\n"
-"		.previous\n"
+	/* This atomically does:
+	 * 	old_val = sem->count;
+	 *	new_val = sem->count - 1;
+	 *	sem->count = new_val;
+	 *	if (old_val < 1)
+	 *		ret = __down_interruptible(sem);
+	 *
+	 * The (old_val < 1) test is equivalent to
+	 * the more straightforward (new_val < 0),
+	 * but it is easier to test the former because
+	 * of how the CAS instruction works.
+	 */
+
+	__asm__ __volatile__("\n"
+"	! down_interruptible sem(%2) ret(%0)\n"
+"1:	lduw	[%2], %%g5\n"
+"	sub	%%g5, 1, %%g7\n"
+"	cas	[%2], %%g5, %%g7\n"
+"	cmp	%%g5, %%g7\n"
+"	bne,pn	%%icc, 1b\n"
+"	 cmp	%%g7, 1\n"
+"	bl,pn	%%icc, 3f\n"
+"	 membar	#StoreStore\n"
+"2:\n"
+"	.subsection 2\n"
+"3:	mov	%2, %%g5\n"
+"	save	%%sp, -160, %%sp\n"
+"	mov	%%g1, %%l1\n"
+"	mov	%%g2, %%l2\n"
+"	mov	%%g3, %%l3\n"
+"	call	%3\n"
+"	 mov	%%g5, %%o0\n"
+"	mov	%%l1, %%g1\n"
+"	mov	%%l2, %%g2\n"
+"	mov	%%l3, %%g3\n"
+"	ba,pt	%%xcc, 2b\n"
+"	 restore %%o0, %%g0, %0\n"
+"	.previous\n"
 	: "=r" (ret)
 	: "0" (ret), "r" (sem), "i" (__down_interruptible)
 	: "g5", "g7", "memory", "cc");
 	return ret;
 }
 
-extern inline int down_trylock(struct semaphore *sem)
+static __inline__ int down_trylock(struct semaphore *sem)
 {
-	int ret = 0;
-#if WAITQUEUE_DEBUG
-	CHECK_MAGIC(sem->__magic);
-#endif
-	__asm__ __volatile__(
-"	1:	lduw	[%2], %%g5\n"
-"		sub	%%g5, 1, %%g7\n"
-"		cas	[%2], %%g5, %%g7\n"
-"		cmp	%%g5, %%g7\n"
-"		bne,pn	%%icc, 1b\n"
-"		 cmp	%%g7, 1\n"
-"		bl,pn	%%icc, 3f\n"
-"		 membar	#StoreStore\n"
-"	2:\n"
-"		.subsection 2\n"
-"	3:	mov	%2, %%g5\n"
-"		save	%%sp, -160, %%sp\n"
-"		mov	%%g1, %%l1\n"
-"		mov	%%g2, %%l2\n"
-"		mov	%%g3, %%l3\n"
-"		call	%3\n"
-"		 mov	%%g5, %%o0\n"
-"		mov	%%l1, %%g1\n"
-"		mov	%%l2, %%g2\n"
-"		mov	%%l3, %%g3\n"
-"		ba,pt	%%xcc, 2b\n"
-"		 restore %%o0, %%g0, %0\n"
-"		.previous\n"
-	: "=r" (ret)
-	: "0" (ret), "r" (sem), "i" (__down_trylock)
+	int ret;
+
+	/* This atomically does:
+	 * 	old_val = sem->count;
+	 *	new_val = sem->count - 1;
+	 *	if (old_val < 1) {
+	 *		ret = 1;
+	 *	} else {
+	 *		sem->count = new_val;
+	 *		ret = 0;
+	 *	}
+	 *
+	 * The (old_val < 1) test is equivalent to
+	 * the more straightforward (new_val < 0),
+	 * but it is easier to test the former because
+	 * of how the CAS instruction works.
+	 */
+
+	__asm__ __volatile__("\n"
+"	! down_trylock sem(%1) ret(%0)\n"
+"1:	lduw	[%1], %%g5\n"
+"	sub	%%g5, 1, %%g7\n"
+"	cmp	%%g5, 1\n"
+"	bl,pn	%%icc, 2f\n"
+"	 mov	1, %0\n"
+"	cas	[%1], %%g5, %%g7\n"
+"	cmp	%%g5, %%g7\n"
+"	bne,pn	%%icc, 1b\n"
+"	 mov	0, %0\n"
+"	membar	#StoreStore\n"
+"2:\n"
+	: "=&r" (ret)
+	: "r" (sem)
 	: "g5", "g7", "memory", "cc");
+
 	return ret;
 }
 
-extern __inline__ void up(struct semaphore * sem)
+static __inline__ void up(struct semaphore * sem)
 {
-#if WAITQUEUE_DEBUG
-	CHECK_MAGIC(sem->__magic);
-#endif
-	__asm__ __volatile__(
-"		membar	#StoreLoad | #LoadLoad\n"
-"	1:	lduw	[%0], %%g5\n"
-"		add	%%g5, 1, %%g7\n"
-"		cas	[%0], %%g5, %%g7\n"
-"		cmp	%%g5, %%g7\n"
-"		bne,pn	%%icc, 1b\n"
-"		 addcc	%%g7, 1, %%g0\n"
-"		ble,pn	%%icc, 3f\n"
-"		 nop\n"
-"	2:\n"
-"		.subsection 2\n"
-"	3:	mov	%0, %%g5\n"
-"		save	%%sp, -160, %%sp\n"
-"		mov	%%g1, %%l1\n"
-"		mov	%%g2, %%l2\n"
-"		mov	%%g3, %%l3\n"
-"		call	%1\n"
-"		 mov	%%g5, %%o0\n"
-"		mov	%%l1, %%g1\n"
-"		mov	%%l2, %%g2\n"
-"		ba,pt	%%xcc, 2b\n"
-"		 restore %%l3, %%g0, %%g3\n"
-"		.previous\n"
+	/* This atomically does:
+	 * 	old_val = sem->count;
+	 *	new_val = sem->count + 1;
+	 *	sem->count = new_val;
+	 *	if (old_val < 0)
+	 *		__up(sem);
+	 *
+	 * The (old_val < 0) test is equivalent to
+	 * the more straightforward (new_val <= 0),
+	 * but it is easier to test the former because
+	 * of how the CAS instruction works.
+	 */
+
+	__asm__ __volatile__("\n"
+"	! up sem(%0)\n"
+"	membar	#StoreLoad | #LoadLoad\n"
+"1:	lduw	[%0], %%g5\n"
+"	add	%%g5, 1, %%g7\n"
+"	cas	[%0], %%g5, %%g7\n"
+"	cmp	%%g5, %%g7\n"
+"	bne,pn	%%icc, 1b\n"
+"	 addcc	%%g7, 1, %%g0\n"
+"	ble,pn	%%icc, 3f\n"
+"	 nop\n"
+"2:\n"
+"	.subsection 2\n"
+"3:	mov	%0, %%g5\n"
+"	save	%%sp, -160, %%sp\n"
+"	mov	%%g1, %%l1\n"
+"	mov	%%g2, %%l2\n"
+"	mov	%%g3, %%l3\n"
+"	call	%1\n"
+"	 mov	%%g5, %%o0\n"
+"	mov	%%l1, %%g1\n"
+"	mov	%%l2, %%g2\n"
+"	ba,pt	%%xcc, 2b\n"
+"	 restore %%l3, %%g0, %%g3\n"
+"	.previous\n"
 	: : "r" (sem), "i" (__up)
 	: "g5", "g7", "memory", "cc");
 }