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/m68knommu/kernel/Makefile | 2 +- arch/m68knommu/kernel/m68k_ksyms.c | 6 -- arch/m68knommu/kernel/semaphore.c | 133 ------------------------------------- arch/m68knommu/lib/Makefile | 2 +- arch/m68knommu/lib/semaphore.S | 66 ------------------ 5 files changed, 2 insertions(+), 207 deletions(-) delete mode 100644 arch/m68knommu/kernel/semaphore.c delete mode 100644 arch/m68knommu/lib/semaphore.S (limited to 'arch/m68knommu') diff --git a/arch/m68knommu/kernel/Makefile b/arch/m68knommu/kernel/Makefile index 1524b39ad63..f0eab3dedb5 100644 --- a/arch/m68knommu/kernel/Makefile +++ b/arch/m68knommu/kernel/Makefile @@ -5,7 +5,7 @@ extra-y := vmlinux.lds obj-y += dma.o entry.o init_task.o irq.o m68k_ksyms.o process.o ptrace.o \ - semaphore.o setup.o signal.o syscalltable.o sys_m68k.o time.o traps.o + setup.o signal.o syscalltable.o sys_m68k.o time.o traps.o obj-$(CONFIG_MODULES) += module.o obj-$(CONFIG_COMEMPCI) += comempci.o diff --git a/arch/m68knommu/kernel/m68k_ksyms.c b/arch/m68knommu/kernel/m68k_ksyms.c index 53fad149028..39fe0a7aec3 100644 --- a/arch/m68knommu/kernel/m68k_ksyms.c +++ b/arch/m68knommu/kernel/m68k_ksyms.c @@ -13,7 +13,6 @@ #include #include #include -#include #include #include @@ -39,11 +38,6 @@ EXPORT_SYMBOL(csum_partial_copy_nocheck); EXPORT_SYMBOL(memcpy); EXPORT_SYMBOL(memset); -EXPORT_SYMBOL(__down_failed); -EXPORT_SYMBOL(__down_failed_interruptible); -EXPORT_SYMBOL(__down_failed_trylock); -EXPORT_SYMBOL(__up_wakeup); - /* * libgcc functions - functions that are used internally by the * compiler... (prototypes are not correct though, but that diff --git a/arch/m68knommu/kernel/semaphore.c b/arch/m68knommu/kernel/semaphore.c deleted file mode 100644 index bce2bc7d87c..00000000000 --- a/arch/m68knommu/kernel/semaphore.c +++ /dev/null @@ -1,133 +0,0 @@ -/* - * Generic semaphore code. Buyer beware. Do your own - * specific changes in - */ - -#include -#include -#include -#include - -#ifndef CONFIG_RMW_INSNS -spinlock_t semaphore_wake_lock; -#endif - -/* - * Semaphores are implemented using a two-way counter: - * The "count" variable is decremented for each process - * that tries to sleep, while the "waking" variable is - * incremented when the "up()" code goes to wake up waiting - * processes. - * - * 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. - * - * waking_non_zero() (from asm/semaphore.h) must execute - * atomically. - * - * When __up() is called, the count was negative before - * incrementing it, and we need to wake up somebody. - * - * This routine adds one to the count of processes that need to - * wake up and exit. ALL waiting processes actually wake up but - * only the one that gets to the "waking" field first will gate - * through and acquire the semaphore. The others will go back - * to sleep. - * - * 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 - * where we want to avoid any extra jumps and calls. - */ -void __up(struct semaphore *sem) -{ - wake_one_more(sem); - wake_up(&sem->wait); -} - -/* - * Perform the "down" function. Return zero for semaphore acquired, - * return negative for signalled out of the function. - * - * If called from __down, the return is ignored and the wait loop is - * not interruptible. This means that a task waiting on a semaphore - * using "down()" cannot be killed until someone does an "up()" on - * the semaphore. - * - * If called from __down_interruptible, the return value gets checked - * upon return. If the return value is negative then the task continues - * with the negative value in the return register (it can be tested by - * the caller). - * - * Either form may be used in conjunction with "up()". - * - */ - - -#define DOWN_HEAD(task_state) \ - \ - \ - current->state = (task_state); \ - add_wait_queue(&sem->wait, &wait); \ - \ - /* \ - * Ok, we're set up. sem->count is known to be less than zero \ - * so we must wait. \ - * \ - * We can let go the lock for purposes of waiting. \ - * We re-acquire it after awaking so as to protect \ - * all semaphore operations. \ - * \ - * If "up()" is called before we call waking_non_zero() then \ - * we will catch it right away. If it is called later then \ - * we will have to go through a wakeup cycle to catch it. \ - * \ - * Multiple waiters contend for the semaphore lock to see \ - * who gets to gate through and who has to wait some more. \ - */ \ - for (;;) { - -#define DOWN_TAIL(task_state) \ - current->state = (task_state); \ - } \ - current->state = TASK_RUNNING; \ - remove_wait_queue(&sem->wait, &wait); - -void __sched __down(struct semaphore * sem) -{ - DECLARE_WAITQUEUE(wait, current); - - DOWN_HEAD(TASK_UNINTERRUPTIBLE) - if (waking_non_zero(sem)) - break; - schedule(); - DOWN_TAIL(TASK_UNINTERRUPTIBLE) -} - -int __sched __down_interruptible(struct semaphore * sem) -{ - DECLARE_WAITQUEUE(wait, current); - int ret = 0; - - DOWN_HEAD(TASK_INTERRUPTIBLE) - - ret = waking_non_zero_interruptible(sem, current); - if (ret) - { - if (ret == 1) - /* ret != 0 only if we get interrupted -arca */ - ret = 0; - break; - } - schedule(); - DOWN_TAIL(TASK_INTERRUPTIBLE) - return ret; -} - -int __down_trylock(struct semaphore * sem) -{ - return waking_non_zero_trylock(sem); -} diff --git a/arch/m68knommu/lib/Makefile b/arch/m68knommu/lib/Makefile index e051a791398..d94d709665a 100644 --- a/arch/m68knommu/lib/Makefile +++ b/arch/m68knommu/lib/Makefile @@ -4,4 +4,4 @@ lib-y := ashldi3.o ashrdi3.o lshrdi3.o \ muldi3.o mulsi3.o divsi3.o udivsi3.o modsi3.o umodsi3.o \ - checksum.o semaphore.o memcpy.o memset.o delay.o + checksum.o memcpy.o memset.o delay.o diff --git a/arch/m68knommu/lib/semaphore.S b/arch/m68knommu/lib/semaphore.S deleted file mode 100644 index 87c74603437..00000000000 --- a/arch/m68knommu/lib/semaphore.S +++ /dev/null @@ -1,66 +0,0 @@ -/* - * linux/arch/m68k/lib/semaphore.S - * - * Copyright (C) 1996 Linus Torvalds - * - * m68k version by Andreas Schwab - * - * MAR/1999 -- modified to support ColdFire (gerg@snapgear.com) - */ - -#include -#include - -/* - * "down_failed" is called with the eventual return address - * in %a0, and the address of the semaphore in %a1. We need - * to increment the number of waiters on the semaphore, - * call "__down()", and then eventually return to try again. - */ -ENTRY(__down_failed) -#ifdef CONFIG_COLDFIRE - subl #12,%sp - moveml %a0/%d0/%d1,(%sp) -#else - moveml %a0/%d0/%d1,-(%sp) -#endif - movel %a1,-(%sp) - jbsr __down - movel (%sp)+,%a1 - movel (%sp)+,%d0 - movel (%sp)+,%d1 - rts - -ENTRY(__down_failed_interruptible) - movel %a0,-(%sp) - movel %d1,-(%sp) - movel %a1,-(%sp) - jbsr __down_interruptible - movel (%sp)+,%a1 - movel (%sp)+,%d1 - rts - -ENTRY(__up_wakeup) -#ifdef CONFIG_COLDFIRE - subl #12,%sp - moveml %a0/%d0/%d1,(%sp) -#else - moveml %a0/%d0/%d1,-(%sp) -#endif - movel %a1,-(%sp) - jbsr __up - movel (%sp)+,%a1 - movel (%sp)+,%d0 - movel (%sp)+,%d1 - rts - -ENTRY(__down_failed_trylock) - movel %a0,-(%sp) - movel %d1,-(%sp) - movel %a1,-(%sp) - jbsr __down_trylock - movel (%sp)+,%a1 - movel (%sp)+,%d1 - movel (%sp)+,%a0 - rts - -- cgit v1.2.3