diff options
Diffstat (limited to 'xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/semaphore.c')
| -rw-r--r-- | xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/semaphore.c | 291 |
1 files changed, 0 insertions, 291 deletions
diff --git a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/semaphore.c b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/semaphore.c deleted file mode 100644 index fd44981804..0000000000 --- a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/semaphore.c +++ /dev/null @@ -1,291 +0,0 @@ -/* - * i386 semaphore implementation. - * - * (C) Copyright 1999 Linus Torvalds - * - * Portions Copyright 1999 Red Hat, Inc. - * - * 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. - * - * rw semaphores implemented November 1999 by Benjamin LaHaise <bcrl@redhat.com> - */ -#include <linux/config.h> -#include <linux/sched.h> -#include <asm/semaphore.h> - -/* - * Semaphores are implemented using a two-way counter: - * The "count" variable is decremented for each process - * that tries to acquire the semaphore, while the "sleeping" - * variable is a count of such acquires. - * - * Notably, the inline "up()" and "down()" functions can - * efficiently test if they need to do any extra work (up - * needs to do something only if count was negative before - * the increment operation. - * - * "sleeping" and the contention routine ordering is - * protected by the semaphore spinlock. - * - * Note that these functions are only called when there is - * contention on the lock, and as such all this is the - * "non-critical" part of the whole semaphore business. The - * critical part is the inline stuff in <asm/semaphore.h> - * where we want to avoid any extra jumps and calls. - */ - -/* - * Logic: - * - only on a boundary condition do we need to care. When we go - * from a negative count to a non-negative, we wake people up. - * - when we go from a non-negative count to a negative do we - * (a) synchronize with the "sleeper" count and (b) make sure - * that we're on the wakeup list before we synchronize so that - * we cannot lose wakeup events. - */ - -void __up(struct semaphore *sem) -{ - wake_up(&sem->wait); -} - -static spinlock_t semaphore_lock = SPIN_LOCK_UNLOCKED; - -void __down(struct semaphore * sem) -{ - struct task_struct *tsk = current; - DECLARE_WAITQUEUE(wait, tsk); - tsk->state = TASK_UNINTERRUPTIBLE; - add_wait_queue_exclusive(&sem->wait, &wait); - - spin_lock_irq(&semaphore_lock); - sem->sleepers++; - for (;;) { - int sleepers = sem->sleepers; - - /* - * Add "everybody else" into it. They aren't - * playing, because we own the spinlock. - */ - if (!atomic_add_negative(sleepers - 1, &sem->count)) { - sem->sleepers = 0; - break; - } - sem->sleepers = 1; /* us - see -1 above */ - spin_unlock_irq(&semaphore_lock); - - schedule(); - tsk->state = TASK_UNINTERRUPTIBLE; - spin_lock_irq(&semaphore_lock); - } - spin_unlock_irq(&semaphore_lock); - remove_wait_queue(&sem->wait, &wait); - tsk->state = TASK_RUNNING; - wake_up(&sem->wait); -} - -int __down_interruptible(struct semaphore * sem) -{ - int retval = 0; - struct task_struct *tsk = current; - DECLARE_WAITQUEUE(wait, tsk); - tsk->state = TASK_INTERRUPTIBLE; - add_wait_queue_exclusive(&sem->wait, &wait); - - spin_lock_irq(&semaphore_lock); - sem->sleepers ++; - for (;;) { - int sleepers = sem->sleepers; - - /* - * With signals pending, this turns into - * the trylock failure case - we won't be - * sleeping, and we* can't get the lock as - * it has contention. Just correct the count - * and exit. - */ - if (signal_pending(current)) { - retval = -EINTR; - sem->sleepers = 0; - atomic_add(sleepers, &sem->count); - break; - } - - /* - * Add "everybody else" into it. They aren't - * playing, because we own the spinlock. The - * "-1" is because we're still hoping to get - * the lock. - */ - if (!atomic_add_negative(sleepers - 1, &sem->count)) { - sem->sleepers = 0; - break; - } - sem->sleepers = 1; /* us - see -1 above */ - spin_unlock_irq(&semaphore_lock); - - schedule(); - tsk->state = TASK_INTERRUPTIBLE; - spin_lock_irq(&semaphore_lock); - } - spin_unlock_irq(&semaphore_lock); - tsk->state = TASK_RUNNING; - remove_wait_queue(&sem->wait, &wait); - wake_up(&sem->wait); - return retval; -} - -/* - * Trylock failed - make sure we correct for - * having decremented the count. - * - * We could have done the trylock with a - * single "cmpxchg" without failure cases, - * but then it wouldn't work on a 386. - */ -int __down_trylock(struct semaphore * sem) -{ - int sleepers; - unsigned long flags; - - spin_lock_irqsave(&semaphore_lock, flags); - sleepers = sem->sleepers + 1; - sem->sleepers = 0; - - /* - * Add "everybody else" and us into it. They aren't - * playing, because we own the spinlock. - */ - if (!atomic_add_negative(sleepers, &sem->count)) - wake_up(&sem->wait); - - spin_unlock_irqrestore(&semaphore_lock, flags); - return 1; -} - - -/* - * The semaphore operations have a special calling sequence that - * allow us to do a simpler in-line version of them. These routines - * need to convert that sequence back into the C sequence when - * there is contention on the semaphore. - * - * %ecx contains the semaphore pointer on entry. Save the C-clobbered - * registers (%eax, %edx and %ecx) except %eax when used as a return - * value.. - */ -asm( -".text\n" -".align 4\n" -".globl __down_failed\n" -"__down_failed:\n\t" -#if defined(CONFIG_FRAME_POINTER) - "pushl %ebp\n\t" - "movl %esp,%ebp\n\t" -#endif - "pushl %eax\n\t" - "pushl %edx\n\t" - "pushl %ecx\n\t" - "call __down\n\t" - "popl %ecx\n\t" - "popl %edx\n\t" - "popl %eax\n\t" -#if defined(CONFIG_FRAME_POINTER) - "movl %ebp,%esp\n\t" - "popl %ebp\n\t" -#endif - "ret" -); - -asm( -".text\n" -".align 4\n" -".globl __down_failed_interruptible\n" -"__down_failed_interruptible:\n\t" -#if defined(CONFIG_FRAME_POINTER) - "pushl %ebp\n\t" - "movl %esp,%ebp\n\t" -#endif - "pushl %edx\n\t" - "pushl %ecx\n\t" - "call __down_interruptible\n\t" - "popl %ecx\n\t" - "popl %edx\n\t" -#if defined(CONFIG_FRAME_POINTER) - "movl %ebp,%esp\n\t" - "popl %ebp\n\t" -#endif - "ret" -); - -asm( -".text\n" -".align 4\n" -".globl __down_failed_trylock\n" -"__down_failed_trylock:\n\t" -#if defined(CONFIG_FRAME_POINTER) - "pushl %ebp\n\t" - "movl %esp,%ebp\n\t" -#endif - "pushl %edx\n\t" - "pushl %ecx\n\t" - "call __down_trylock\n\t" - "popl %ecx\n\t" - "popl %edx\n\t" -#if defined(CONFIG_FRAME_POINTER) - "movl %ebp,%esp\n\t" - "popl %ebp\n\t" -#endif - "ret" -); - -asm( -".text\n" -".align 4\n" -".globl __up_wakeup\n" -"__up_wakeup:\n\t" - "pushl %eax\n\t" - "pushl %edx\n\t" - "pushl %ecx\n\t" - "call __up\n\t" - "popl %ecx\n\t" - "popl %edx\n\t" - "popl %eax\n\t" - "ret" -); - -/* - * rw spinlock fallbacks - */ -#if defined(CONFIG_SMP) -asm( -".text\n" -".align 4\n" -".globl __write_lock_failed\n" -"__write_lock_failed:\n\t" - LOCK "addl $" RW_LOCK_BIAS_STR ",(%eax)\n" -"1: rep; nop\n\t" - "cmpl $" RW_LOCK_BIAS_STR ",(%eax)\n\t" - "jne 1b\n\t" - LOCK "subl $" RW_LOCK_BIAS_STR ",(%eax)\n\t" - "jnz __write_lock_failed\n\t" - "ret" -); - -asm( -".text\n" -".align 4\n" -".globl __read_lock_failed\n" -"__read_lock_failed:\n\t" - LOCK "incl (%eax)\n" -"1: rep; nop\n\t" - "cmpl $1,(%eax)\n\t" - "js 1b\n\t" - LOCK "decl (%eax)\n\t" - "js __read_lock_failed\n\t" - "ret" -); -#endif |