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authorBenjamin LaHaise <bcrl@kvack.org>2005-09-03 15:56:52 -0700
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 00:06:14 -0700
commit52fdd08903a1d1162e184114837e232640191627 (patch)
tree9469f521b7ba12ac48337155bc5a65049d361229 /arch/x86_64
parent4ad8d38342430f8b52f7a8458dce90caf8c8ca64 (diff)
[PATCH] unify x86/x86-64 semaphore code
This patch moves the common code in x86 and x86-64's semaphore.c into a single file in lib/semaphore-sleepers.c. The arch specific asm stubs are left in the arch tree (in semaphore.c for i386 and in the asm for x86-64). There should be no changes in code/functionality with this patch. Signed-off-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/x86_64')
-rw-r--r--arch/x86_64/Kconfig4
-rw-r--r--arch/x86_64/kernel/Makefile2
-rw-r--r--arch/x86_64/kernel/semaphore.c180
3 files changed, 5 insertions, 181 deletions
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index 660a03a89e6..75e52c57f19 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -24,6 +24,10 @@ config X86
bool
default y
+config SEMAPHORE_SLEEPERS
+ bool
+ default y
+
config MMU
bool
default y
diff --git a/arch/x86_64/kernel/Makefile b/arch/x86_64/kernel/Makefile
index 48f9e2c19cd..427501a336c 100644
--- a/arch/x86_64/kernel/Makefile
+++ b/arch/x86_64/kernel/Makefile
@@ -4,7 +4,7 @@
extra-y := head.o head64.o init_task.o vmlinux.lds
EXTRA_AFLAGS := -traditional
-obj-y := process.o semaphore.o signal.o entry.o traps.o irq.o \
+obj-y := process.o signal.o entry.o traps.o irq.o \
ptrace.o time.o ioport.o ldt.o setup.o i8259.o sys_x86_64.o \
x8664_ksyms.o i387.o syscall.o vsyscall.o \
setup64.o bootflag.o e820.o reboot.o quirks.o
diff --git a/arch/x86_64/kernel/semaphore.c b/arch/x86_64/kernel/semaphore.c
deleted file mode 100644
index 48f7c18172b..00000000000
--- a/arch/x86_64/kernel/semaphore.c
+++ /dev/null
@@ -1,180 +0,0 @@
-/*
- * x86_64 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@kvack.org>
- */
-#include <linux/config.h>
-#include <linux/sched.h>
-#include <linux/init.h>
-#include <asm/errno.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 spinlock in the semaphore's waitqueue head.
- *
- * 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);
-}
-
-void __sched __down(struct semaphore * sem)
-{
- struct task_struct *tsk = current;
- DECLARE_WAITQUEUE(wait, tsk);
- unsigned long flags;
-
- tsk->state = TASK_UNINTERRUPTIBLE;
- spin_lock_irqsave(&sem->wait.lock, flags);
- add_wait_queue_exclusive_locked(&sem->wait, &wait);
-
- sem->sleepers++;
- for (;;) {
- int sleepers = sem->sleepers;
-
- /*
- * Add "everybody else" into it. They aren't
- * playing, because we own the spinlock in
- * the wait_queue_head.
- */
- if (!atomic_add_negative(sleepers - 1, &sem->count)) {
- sem->sleepers = 0;
- break;
- }
- sem->sleepers = 1; /* us - see -1 above */
- spin_unlock_irqrestore(&sem->wait.lock, flags);
-
- schedule();
-
- spin_lock_irqsave(&sem->wait.lock, flags);
- tsk->state = TASK_UNINTERRUPTIBLE;
- }
- remove_wait_queue_locked(&sem->wait, &wait);
- wake_up_locked(&sem->wait);
- spin_unlock_irqrestore(&sem->wait.lock, flags);
- tsk->state = TASK_RUNNING;
-}
-
-int __sched __down_interruptible(struct semaphore * sem)
-{
- int retval = 0;
- struct task_struct *tsk = current;
- DECLARE_WAITQUEUE(wait, tsk);
- unsigned long flags;
-
- tsk->state = TASK_INTERRUPTIBLE;
- spin_lock_irqsave(&sem->wait.lock, flags);
- add_wait_queue_exclusive_locked(&sem->wait, &wait);
-
- 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 in
- * wait_queue_head. The "-1" is because we're
- * still hoping to get the semaphore.
- */
- if (!atomic_add_negative(sleepers - 1, &sem->count)) {
- sem->sleepers = 0;
- break;
- }
- sem->sleepers = 1; /* us - see -1 above */
- spin_unlock_irqrestore(&sem->wait.lock, flags);
-
- schedule();
-
- spin_lock_irqsave(&sem->wait.lock, flags);
- tsk->state = TASK_INTERRUPTIBLE;
- }
- remove_wait_queue_locked(&sem->wait, &wait);
- wake_up_locked(&sem->wait);
- spin_unlock_irqrestore(&sem->wait.lock, flags);
-
- tsk->state = TASK_RUNNING;
- 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(&sem->wait.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 in the
- * wait_queue_head.
- */
- if (!atomic_add_negative(sleepers, &sem->count)) {
- wake_up_locked(&sem->wait);
- }
-
- spin_unlock_irqrestore(&sem->wait.lock, flags);
- return 1;
-}
-
-