From 64ac24e738823161693bf791f87adc802cf529ff Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 7 Mar 2008 21:55:58 -0500 Subject: Generic semaphore implementation Semaphores are no longer performance-critical, so a generic C implementation is better for maintainability, debuggability and extensibility. Thanks to Peter Zijlstra for fixing the lockdep warning. Thanks to Harvey Harrison for pointing out that the unlikely() was unnecessary. Signed-off-by: Matthew Wilcox Acked-by: Ingo Molnar --- arch/frv/kernel/Makefile | 2 +- arch/frv/kernel/frv_ksyms.c | 1 - arch/frv/kernel/semaphore.c | 155 -------------------------------------------- 3 files changed, 1 insertion(+), 157 deletions(-) delete mode 100644 arch/frv/kernel/semaphore.c (limited to 'arch/frv') diff --git a/arch/frv/kernel/Makefile b/arch/frv/kernel/Makefile index e8f73ed28b52..c36f70b6699a 100644 --- a/arch/frv/kernel/Makefile +++ b/arch/frv/kernel/Makefile @@ -9,7 +9,7 @@ extra-y:= head.o init_task.o vmlinux.lds obj-y := $(heads-y) entry.o entry-table.o break.o switch_to.o kernel_thread.o \ kernel_execve.o process.o traps.o ptrace.o signal.o dma.o \ - sys_frv.o time.o semaphore.o setup.o frv_ksyms.o \ + sys_frv.o time.o setup.o frv_ksyms.o \ debug-stub.o irq.o sleep.o uaccess.o obj-$(CONFIG_GDBSTUB) += gdb-stub.o gdb-io.o diff --git a/arch/frv/kernel/frv_ksyms.c b/arch/frv/kernel/frv_ksyms.c index f772704b3d28..0316b3c50eff 100644 --- a/arch/frv/kernel/frv_ksyms.c +++ b/arch/frv/kernel/frv_ksyms.c @@ -12,7 +12,6 @@ #include #include #include -#include #include #include #include diff --git a/arch/frv/kernel/semaphore.c b/arch/frv/kernel/semaphore.c deleted file mode 100644 index 7ee3a147b471..000000000000 --- a/arch/frv/kernel/semaphore.c +++ /dev/null @@ -1,155 +0,0 @@ -/* semaphore.c: FR-V semaphores - * - * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved. - * Written by David Howells (dhowells@redhat.com) - * - Derived from lib/rwsem-spinlock.c - * - * 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. - */ - -#include -#include -#include - -struct sem_waiter { - struct list_head list; - struct task_struct *task; -}; - -#ifdef CONFIG_DEBUG_SEMAPHORE -void semtrace(struct semaphore *sem, const char *str) -{ - if (sem->debug) - printk("[%d] %s({%d,%d})\n", - current->pid, - str, - sem->counter, - list_empty(&sem->wait_list) ? 0 : 1); -} -#else -#define semtrace(SEM,STR) do { } while(0) -#endif - -/* - * wait for a token to be granted from a semaphore - * - entered with lock held and interrupts disabled - */ -void __down(struct semaphore *sem, unsigned long flags) -{ - struct task_struct *tsk = current; - struct sem_waiter waiter; - - semtrace(sem, "Entering __down"); - - /* set up my own style of waitqueue */ - waiter.task = tsk; - get_task_struct(tsk); - - list_add_tail(&waiter.list, &sem->wait_list); - - /* we don't need to touch the semaphore struct anymore */ - spin_unlock_irqrestore(&sem->wait_lock, flags); - - /* wait to be given the semaphore */ - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - - for (;;) { - if (list_empty(&waiter.list)) - break; - schedule(); - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - } - - tsk->state = TASK_RUNNING; - semtrace(sem, "Leaving __down"); -} - -EXPORT_SYMBOL(__down); - -/* - * interruptibly wait for a token to be granted from a semaphore - * - entered with lock held and interrupts disabled - */ -int __down_interruptible(struct semaphore *sem, unsigned long flags) -{ - struct task_struct *tsk = current; - struct sem_waiter waiter; - int ret; - - semtrace(sem,"Entering __down_interruptible"); - - /* set up my own style of waitqueue */ - waiter.task = tsk; - get_task_struct(tsk); - - list_add_tail(&waiter.list, &sem->wait_list); - - /* we don't need to touch the semaphore struct anymore */ - set_task_state(tsk, TASK_INTERRUPTIBLE); - - spin_unlock_irqrestore(&sem->wait_lock, flags); - - /* wait to be given the semaphore */ - ret = 0; - for (;;) { - if (list_empty(&waiter.list)) - break; - if (unlikely(signal_pending(current))) - goto interrupted; - schedule(); - set_task_state(tsk, TASK_INTERRUPTIBLE); - } - - out: - tsk->state = TASK_RUNNING; - semtrace(sem, "Leaving __down_interruptible"); - return ret; - - interrupted: - spin_lock_irqsave(&sem->wait_lock, flags); - - if (!list_empty(&waiter.list)) { - list_del(&waiter.list); - ret = -EINTR; - } - - spin_unlock_irqrestore(&sem->wait_lock, flags); - if (ret == -EINTR) - put_task_struct(current); - goto out; -} - -EXPORT_SYMBOL(__down_interruptible); - -/* - * release a single token back to a semaphore - * - entered with lock held and interrupts disabled - */ -void __up(struct semaphore *sem) -{ - struct task_struct *tsk; - struct sem_waiter *waiter; - - semtrace(sem,"Entering __up"); - - /* grant the token to the process at the front of the queue */ - waiter = list_entry(sem->wait_list.next, struct sem_waiter, list); - - /* We must be careful not to touch 'waiter' after we set ->task = NULL. - * It is allocated on the waiter's stack and may become invalid at - * any time after that point (due to a wakeup from another source). - */ - list_del_init(&waiter->list); - tsk = waiter->task; - mb(); - waiter->task = NULL; - wake_up_process(tsk); - put_task_struct(tsk); - - semtrace(sem,"Leaving __up"); -} - -EXPORT_SYMBOL(__up); -- cgit v1.2.3