| /* include/asm-i386/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. |
| * |
| * 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_I386_RWLOCK_H |
| #define _ASM_I386_RWLOCK_H |
| |
| #define RW_LOCK_BIAS 0x01000000 |
| #define RW_LOCK_BIAS_STR "0x01000000" |
| |
| #define __build_read_lock(rw, helper) \ |
| asm volatile(LOCK_PREFIX " subl $1,(%0)\n\t" \ |
| "jns 1f\n" \ |
| "call " helper "\n\t" \ |
| "1:\n" \ |
| ::"a" (rw) : "memory") |
| |
| #define __build_write_lock(rw, helper) \ |
| asm volatile(LOCK_PREFIX " subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \ |
| "jz 1f\n" \ |
| "call " helper "\n\t" \ |
| "1:\n" \ |
| ::"a" (rw) : "memory") |
| |
| #endif |