patch-2.4.20 linux-2.4.20/include/asm-x86_64/rwlock.h

• Lines: 87
• Date: Thu Nov 28 15:53:15 2002
• Orig file: linux-2.4.19/include/asm-x86_64/rwlock.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.19/include/asm-x86_64/rwlock.h linux-2.4.20/include/asm-x86_64/rwlock.h
@@ -0,0 +1,86 @@
+/* include/asm-x86_64/rwlock.h
+ *
+ *	Helpers used by both rw spinlocks and rw semaphores.
+ *
+ *	Based in part on code from semaphore.h and
+ *	spinlock.h Copyright 1996 Linus Torvalds.
+ *
+ *	Copyright 1999 Red Hat, Inc.
+ *	Copyright 2001,2002 SuSE labs 
+ *
+ *	Written by Benjamin LaHaise.
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ */
+#ifndef _ASM_X86_64_RWLOCK_H
+#define _ASM_X86_64_RWLOCK_H
+
+#include <linux/stringify.h>
+
+#define RW_LOCK_BIAS		 0x01000000
+#define RW_LOCK_BIAS_STR	"0x01000000"
+
+#define __build_read_lock_ptr(rw, helper)   \
+	asm volatile(LOCK "subl $1,(%0)\n\t" \
+		     "js 2f\n" \
+		     "1:\n" \
+		    LOCK_SECTION_START("") \
+		     "2:\tcall " helper "\n\t" \
+		     "jmp 1b\n" \
+		    LOCK_SECTION_END \
+		     ::"a" (rw) : "memory")
+
+#define __build_read_lock_const(rw, helper)   \
+	asm volatile(LOCK "subl $1,%0\n\t" \
+		     "js 2f\n" \
+		     "1:\n" \
+		    LOCK_SECTION_START("") \
+		     "2:\tpushq %%rax\n\t" \
+		     "leaq %0,%%rax\n\t" \
+		     "call " helper "\n\t" \
+		     "popq %%rax\n\t" \
+		     "jmp 1b\n" \
+		    LOCK_SECTION_END \
+		     :"=m" (*((volatile int *)rw))::"memory")
+
+#define __build_read_lock(rw, helper)	do { \
+						if (__builtin_constant_p(rw)) \
+							__build_read_lock_const(rw, helper); \
+						else \
+							__build_read_lock_ptr(rw, helper); \
+					} while (0)
+
+#define __build_write_lock_ptr(rw, helper) \
+	asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \
+		     "jnz 2f\n" \
+		     "1:\n" \
+		     LOCK_SECTION_START("") \
+		     "2:\tcall " helper "\n\t" \
+		     "jmp 1b\n" \
+		     LOCK_SECTION_END \
+		     ::"a" (rw) : "memory")
+
+#define __build_write_lock_const(rw, helper) \
+	asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \
+		     "jnz 2f\n" \
+		     "1:\n" \
+		    LOCK_SECTION_START("") \
+		     "2:\tpushq %%rax\n\t" \
+		     "leaq %0,%%rax\n\t" \
+		     "call " helper "\n\t" \
+		     "popq %%rax\n\t" \
+		     "jmp 1b\n" \
+		    LOCK_SECTION_END \
+		     :"=m" (*((volatile long *)rw))::"memory")
+
+#define __build_write_lock(rw, helper)	do { \
+						if (__builtin_constant_p(rw)) \
+							__build_write_lock_const(rw, helper); \
+						else \
+							__build_write_lock_ptr(rw, helper); \
+					} while (0)
+
+#endif