[RFC 4/8] locking: Move semaphore into kernel/locking/

[Peter Zijlstra <peterz@infradead.org>]

[-- Attachment #1: peterz-move-locking-semaphore.patch --]
[-- Type: text/plain, Size: 17031 bytes --]


Cc: willy@linux.intel.com
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
---
 kernel/Makefile            |    2 
 kernel/locking/Makefile    |    2 
 kernel/locking/semaphore.c |  263 +++++++++++++++++++++++++++++++++++++++++++++
 kernel/semaphore.c         |  263 ---------------------------------------------
 4 files changed, 265 insertions(+), 265 deletions(-)

Index: linux-2.6/kernel/Makefile
===================================================================
--- linux-2.6.orig/kernel/Makefile
+++ linux-2.6/kernel/Makefile
@@ -8,7 +8,7 @@ obj-y     = fork.o exec_domain.o panic.o
 	    signal.o sys.o kmod.o workqueue.o pid.o task_work.o \
 	    extable.o params.o posix-timers.o \
 	    kthread.o sys_ni.o posix-cpu-timers.o \
-	    hrtimer.o rwsem.o nsproxy.o semaphore.o \
+	    hrtimer.o rwsem.o nsproxy.o \
 	    notifier.o ksysfs.o cred.o reboot.o \
 	    async.o range.o groups.o lglock.o smpboot.o
 
Index: linux-2.6/kernel/locking/Makefile
===================================================================
--- linux-2.6.orig/kernel/locking/Makefile
+++ linux-2.6/kernel/locking/Makefile
@@ -1,5 +1,5 @@
 
-obj-y += mutex.o
+obj-y += mutex.o semaphore.o
 
 ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_lockdep.o = -pg
Index: linux-2.6/kernel/locking/semaphore.c
===================================================================
--- /dev/null
+++ linux-2.6/kernel/locking/semaphore.c
@@ -0,0 +1,263 @@
+/*
+ * Copyright (c) 2008 Intel Corporation
+ * Author: Matthew Wilcox <willy@linux.intel.com>
+ *
+ * Distributed under the terms of the GNU GPL, version 2
+ *
+ * This file implements counting semaphores.
+ * A counting semaphore may be acquired 'n' times before sleeping.
+ * See mutex.c for single-acquisition sleeping locks which enforce
+ * rules which allow code to be debugged more easily.
+ */
+
+/*
+ * Some notes on the implementation:
+ *
+ * The spinlock controls access to the other members of the semaphore.
+ * down_trylock() and up() can be called from interrupt context, so we
+ * have to disable interrupts when taking the lock.  It turns out various
+ * parts of the kernel expect to be able to use down() on a semaphore in
+ * interrupt context when they know it will succeed, so we have to use
+ * irqsave variants for down(), down_interruptible() and down_killable()
+ * too.
+ *
+ * The ->count variable represents how many more tasks can acquire this
+ * semaphore.  If it's zero, there may be tasks waiting on the wait_list.
+ */
+
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/semaphore.h>
+#include <linux/spinlock.h>
+#include <linux/ftrace.h>
+
+static noinline void __down(struct semaphore *sem);
+static noinline int __down_interruptible(struct semaphore *sem);
+static noinline int __down_killable(struct semaphore *sem);
+static noinline int __down_timeout(struct semaphore *sem, long jiffies);
+static noinline void __up(struct semaphore *sem);
+
+/**
+ * down - acquire the semaphore
+ * @sem: the semaphore to be acquired
+ *
+ * Acquires the semaphore.  If no more tasks are allowed to acquire the
+ * semaphore, calling this function will put the task to sleep until the
+ * semaphore is released.
+ *
+ * Use of this function is deprecated, please use down_interruptible() or
+ * down_killable() instead.
+ */
+void down(struct semaphore *sem)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	if (likely(sem->count > 0))
+		sem->count--;
+	else
+		__down(sem);
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+}
+EXPORT_SYMBOL(down);
+
+/**
+ * down_interruptible - acquire the semaphore unless interrupted
+ * @sem: the semaphore to be acquired
+ *
+ * Attempts to acquire the semaphore.  If no more tasks are allowed to
+ * acquire the semaphore, calling this function will put the task to sleep.
+ * If the sleep is interrupted by a signal, this function will return -EINTR.
+ * If the semaphore is successfully acquired, this function returns 0.
+ */
+int down_interruptible(struct semaphore *sem)
+{
+	unsigned long flags;
+	int result = 0;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	if (likely(sem->count > 0))
+		sem->count--;
+	else
+		result = __down_interruptible(sem);
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+	return result;
+}
+EXPORT_SYMBOL(down_interruptible);
+
+/**
+ * down_killable - acquire the semaphore unless killed
+ * @sem: the semaphore to be acquired
+ *
+ * Attempts to acquire the semaphore.  If no more tasks are allowed to
+ * acquire the semaphore, calling this function will put the task to sleep.
+ * If the sleep is interrupted by a fatal signal, this function will return
+ * -EINTR.  If the semaphore is successfully acquired, this function returns
+ * 0.
+ */
+int down_killable(struct semaphore *sem)
+{
+	unsigned long flags;
+	int result = 0;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	if (likely(sem->count > 0))
+		sem->count--;
+	else
+		result = __down_killable(sem);
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+	return result;
+}
+EXPORT_SYMBOL(down_killable);
+
+/**
+ * down_trylock - try to acquire the semaphore, without waiting
+ * @sem: the semaphore to be acquired
+ *
+ * Try to acquire the semaphore atomically.  Returns 0 if the semaphore has
+ * been acquired successfully or 1 if it it cannot be acquired.
+ *
+ * NOTE: This return value is inverted from both spin_trylock and
+ * mutex_trylock!  Be careful about this when converting code.
+ *
+ * Unlike mutex_trylock, this function can be used from interrupt context,
+ * and the semaphore can be released by any task or interrupt.
+ */
+int down_trylock(struct semaphore *sem)
+{
+	unsigned long flags;
+	int count;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	count = sem->count - 1;
+	if (likely(count >= 0))
+		sem->count = count;
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+	return (count < 0);
+}
+EXPORT_SYMBOL(down_trylock);
+
+/**
+ * down_timeout - acquire the semaphore within a specified time
+ * @sem: the semaphore to be acquired
+ * @jiffies: how long to wait before failing
+ *
+ * Attempts to acquire the semaphore.  If no more tasks are allowed to
+ * acquire the semaphore, calling this function will put the task to sleep.
+ * If the semaphore is not released within the specified number of jiffies,
+ * this function returns -ETIME.  It returns 0 if the semaphore was acquired.
+ */
+int down_timeout(struct semaphore *sem, long jiffies)
+{
+	unsigned long flags;
+	int result = 0;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	if (likely(sem->count > 0))
+		sem->count--;
+	else
+		result = __down_timeout(sem, jiffies);
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+
+	return result;
+}
+EXPORT_SYMBOL(down_timeout);
+
+/**
+ * up - release the semaphore
+ * @sem: the semaphore to release
+ *
+ * Release the semaphore.  Unlike mutexes, up() may be called from any
+ * context and even by tasks which have never called down().
+ */
+void up(struct semaphore *sem)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&sem->lock, flags);
+	if (likely(list_empty(&sem->wait_list)))
+		sem->count++;
+	else
+		__up(sem);
+	raw_spin_unlock_irqrestore(&sem->lock, flags);
+}
+EXPORT_SYMBOL(up);
+
+/* Functions for the contended case */
+
+struct semaphore_waiter {
+	struct list_head list;
+	struct task_struct *task;
+	bool up;
+};
+
+/*
+ * Because this function is inlined, the 'state' parameter will be
+ * constant, and thus optimised away by the compiler.  Likewise the
+ * 'timeout' parameter for the cases without timeouts.
+ */
+static inline int __sched __down_common(struct semaphore *sem, long state,
+								long timeout)
+{
+	struct task_struct *task = current;
+	struct semaphore_waiter waiter;
+
+	list_add_tail(&waiter.list, &sem->wait_list);
+	waiter.task = task;
+	waiter.up = false;
+
+	for (;;) {
+		if (signal_pending_state(state, task))
+			goto interrupted;
+		if (unlikely(timeout <= 0))
+			goto timed_out;
+		__set_task_state(task, state);
+		raw_spin_unlock_irq(&sem->lock);
+		timeout = schedule_timeout(timeout);
+		raw_spin_lock_irq(&sem->lock);
+		if (waiter.up)
+			return 0;
+	}
+
+ timed_out:
+	list_del(&waiter.list);
+	return -ETIME;
+
+ interrupted:
+	list_del(&waiter.list);
+	return -EINTR;
+}
+
+static noinline void __sched __down(struct semaphore *sem)
+{
+	__down_common(sem, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+}
+
+static noinline int __sched __down_interruptible(struct semaphore *sem)
+{
+	return __down_common(sem, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+}
+
+static noinline int __sched __down_killable(struct semaphore *sem)
+{
+	return __down_common(sem, TASK_KILLABLE, MAX_SCHEDULE_TIMEOUT);
+}
+
+static noinline int __sched __down_timeout(struct semaphore *sem, long jiffies)
+{
+	return __down_common(sem, TASK_UNINTERRUPTIBLE, jiffies);
+}
+
+static noinline void __sched __up(struct semaphore *sem)
+{
+	struct semaphore_waiter *waiter = list_first_entry(&sem->wait_list,
+						struct semaphore_waiter, list);
+	list_del(&waiter->list);
+	waiter->up = true;
+	wake_up_process(waiter->task);
+}
Index: linux-2.6/kernel/semaphore.c
===================================================================
--- linux-2.6.orig/kernel/semaphore.c
+++ /dev/null
@@ -1,263 +0,0 @@
-/*
- * Copyright (c) 2008 Intel Corporation
- * Author: Matthew Wilcox <willy@linux.intel.com>
- *
- * Distributed under the terms of the GNU GPL, version 2
- *
- * This file implements counting semaphores.
- * A counting semaphore may be acquired 'n' times before sleeping.
- * See mutex.c for single-acquisition sleeping locks which enforce
- * rules which allow code to be debugged more easily.
- */
-
-/*
- * Some notes on the implementation:
- *
- * The spinlock controls access to the other members of the semaphore.
- * down_trylock() and up() can be called from interrupt context, so we
- * have to disable interrupts when taking the lock.  It turns out various
- * parts of the kernel expect to be able to use down() on a semaphore in
- * interrupt context when they know it will succeed, so we have to use
- * irqsave variants for down(), down_interruptible() and down_killable()
- * too.
- *
- * The ->count variable represents how many more tasks can acquire this
- * semaphore.  If it's zero, there may be tasks waiting on the wait_list.
- */
-
-#include <linux/compiler.h>
-#include <linux/kernel.h>
-#include <linux/export.h>
-#include <linux/sched.h>
-#include <linux/semaphore.h>
-#include <linux/spinlock.h>
-#include <linux/ftrace.h>
-
-static noinline void __down(struct semaphore *sem);
-static noinline int __down_interruptible(struct semaphore *sem);
-static noinline int __down_killable(struct semaphore *sem);
-static noinline int __down_timeout(struct semaphore *sem, long jiffies);
-static noinline void __up(struct semaphore *sem);
-
-/**
- * down - acquire the semaphore
- * @sem: the semaphore to be acquired
- *
- * Acquires the semaphore.  If no more tasks are allowed to acquire the
- * semaphore, calling this function will put the task to sleep until the
- * semaphore is released.
- *
- * Use of this function is deprecated, please use down_interruptible() or
- * down_killable() instead.
- */
-void down(struct semaphore *sem)
-{
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&sem->lock, flags);
-	if (likely(sem->count > 0))
-		sem->count--;
-	else
-		__down(sem);
-	raw_spin_unlock_irqrestore(&sem->lock, flags);
-}
-EXPORT_SYMBOL(down);
-
-/**
- * down_interruptible - acquire the semaphore unless interrupted
- * @sem: the semaphore to be acquired
- *
- * Attempts to acquire the semaphore.  If no more tasks are allowed to
- * acquire the semaphore, calling this function will put the task to sleep.
- * If the sleep is interrupted by a signal, this function will return -EINTR.
- * If the semaphore is successfully acquired, this function returns 0.
- */
-int down_interruptible(struct semaphore *sem)
-{
-	unsigned long flags;
-	int result = 0;
-
-	raw_spin_lock_irqsave(&sem->lock, flags);
-	if (likely(sem->count > 0))
-		sem->count--;
-	else
-		result = __down_interruptible(sem);
-	raw_spin_unlock_irqrestore(&sem->lock, flags);
-
-	return result;
-}
-EXPORT_SYMBOL(down_interruptible);
-
-/**
- * down_killable - acquire the semaphore unless killed
- * @sem: the semaphore to be acquired
- *
- * Attempts to acquire the semaphore.  If no more tasks are allowed to
- * acquire the semaphore, calling this function will put the task to sleep.
- * If the sleep is interrupted by a fatal signal, this function will return
- * -EINTR.  If the semaphore is successfully acquired, this function returns
- * 0.
- */
-int down_killable(struct semaphore *sem)
-{
-	unsigned long flags;
-	int result = 0;
-
-	raw_spin_lock_irqsave(&sem->lock, flags);
-	if (likely(sem->count > 0))
-		sem->count--;
-	else
-		result = __down_killable(sem);
-	raw_spin_unlock_irqrestore(&sem->lock, flags);
-
-	return result;
-}
-EXPORT_SYMBOL(down_killable);
-
-/**
- * down_trylock - try to acquire the semaphore, without waiting
- * @sem: the semaphore to be acquired
- *
- * Try to acquire the semaphore atomically.  Returns 0 if the semaphore has
- * been acquired successfully or 1 if it it cannot be acquired.
- *
- * NOTE: This return value is inverted from both spin_trylock and
- * mutex_trylock!  Be careful about this when converting code.
- *
- * Unlike mutex_trylock, this function can be used from interrupt context,
- * and the semaphore can be released by any task or interrupt.
- */
-int down_trylock(struct semaphore *sem)
-{
-	unsigned long flags;
-	int count;
-
-	raw_spin_lock_irqsave(&sem->lock, flags);
-	count = sem->count - 1;
-	if (likely(count >= 0))
-		sem->count = count;
-	raw_spin_unlock_irqrestore(&sem->lock, flags);
-
-	return (count < 0);
-}
-EXPORT_SYMBOL(down_trylock);
-
-/**
- * down_timeout - acquire the semaphore within a specified time
- * @sem: the semaphore to be acquired
- * @jiffies: how long to wait before failing
- *
- * Attempts to acquire the semaphore.  If no more tasks are allowed to
- * acquire the semaphore, calling this function will put the task to sleep.
- * If the semaphore is not released within the specified number of jiffies,
- * this function returns -ETIME.  It returns 0 if the semaphore was acquired.
- */
-int down_timeout(struct semaphore *sem, long jiffies)
-{
-	unsigned long flags;
-	int result = 0;
-
-	raw_spin_lock_irqsave(&sem->lock, flags);
-	if (likely(sem->count > 0))
-		sem->count--;
-	else
-		result = __down_timeout(sem, jiffies);
-	raw_spin_unlock_irqrestore(&sem->lock, flags);
-
-	return result;
-}
-EXPORT_SYMBOL(down_timeout);
-
-/**
- * up - release the semaphore
- * @sem: the semaphore to release
- *
- * Release the semaphore.  Unlike mutexes, up() may be called from any
- * context and even by tasks which have never called down().
- */
-void up(struct semaphore *sem)
-{
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&sem->lock, flags);
-	if (likely(list_empty(&sem->wait_list)))
-		sem->count++;
-	else
-		__up(sem);
-	raw_spin_unlock_irqrestore(&sem->lock, flags);
-}
-EXPORT_SYMBOL(up);
-
-/* Functions for the contended case */
-
-struct semaphore_waiter {
-	struct list_head list;
-	struct task_struct *task;
-	bool up;
-};
-
-/*
- * Because this function is inlined, the 'state' parameter will be
- * constant, and thus optimised away by the compiler.  Likewise the
- * 'timeout' parameter for the cases without timeouts.
- */
-static inline int __sched __down_common(struct semaphore *sem, long state,
-								long timeout)
-{
-	struct task_struct *task = current;
-	struct semaphore_waiter waiter;
-
-	list_add_tail(&waiter.list, &sem->wait_list);
-	waiter.task = task;
-	waiter.up = false;
-
-	for (;;) {
-		if (signal_pending_state(state, task))
-			goto interrupted;
-		if (unlikely(timeout <= 0))
-			goto timed_out;
-		__set_task_state(task, state);
-		raw_spin_unlock_irq(&sem->lock);
-		timeout = schedule_timeout(timeout);
-		raw_spin_lock_irq(&sem->lock);
-		if (waiter.up)
-			return 0;
-	}
-
- timed_out:
-	list_del(&waiter.list);
-	return -ETIME;
-
- interrupted:
-	list_del(&waiter.list);
-	return -EINTR;
-}
-
-static noinline void __sched __down(struct semaphore *sem)
-{
-	__down_common(sem, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
-}
-
-static noinline int __sched __down_interruptible(struct semaphore *sem)
-{
-	return __down_common(sem, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
-}
-
-static noinline int __sched __down_killable(struct semaphore *sem)
-{
-	return __down_common(sem, TASK_KILLABLE, MAX_SCHEDULE_TIMEOUT);
-}
-
-static noinline int __sched __down_timeout(struct semaphore *sem, long jiffies)
-{
-	return __down_common(sem, TASK_UNINTERRUPTIBLE, jiffies);
-}
-
-static noinline void __sched __up(struct semaphore *sem)
-{
-	struct semaphore_waiter *waiter = list_first_entry(&sem->wait_list,
-						struct semaphore_waiter, list);
-	list_del(&waiter->list);
-	waiter->up = true;
-	wake_up_process(waiter->task);
-}