/* $Id: virtual_stub.c,v 1.26.2.9 2009/01/23 17:21:20 mikpe Exp $

 * Kernel stub used to support virtual perfctrs when the

 * perfctr driver is built as a module.

 *

 * Copyright (C) 2000-2009  Mikael Pettersson

 */

#include <linux/version.h>

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)

#include <linux/config.h>

#endif

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/perfctr.h>

#include "compat.h"

static void bug_void_perfctr(struct vperfctr *perfctr)

{

	current->thread.perfctr = NULL;

	BUG();

}

#ifdef CONFIG_PERFCTR_CPUS_FORBIDDEN_MASK

static void bug_set_cpus_allowed(struct task_struct *owner, struct vperfctr *perfctr, cpumask_t new_mask)

{

	owner->thread.perfctr = NULL;

	BUG();

}

#endif

struct vperfctr_stub vperfctr_stub = {

	.exit = bug_void_perfctr,

	.flush = bug_void_perfctr,

	.suspend = bug_void_perfctr,

	.resume = bug_void_perfctr,

	.sample = bug_void_perfctr,

#ifdef CONFIG_PERFCTR_CPUS_FORBIDDEN_MASK

	.set_cpus_allowed = bug_set_cpus_allowed,

#endif

};

/*

 * exit_thread() calls __vperfctr_exit() via vperfctr_stub.exit().

 * If the process' reference was the last reference to this

 * vperfctr object, and this was the last live vperfctr object,

 * then the perfctr module's use count will drop to zero.

 * This is Ok, except for the fact that code is still running

 * in the module (pending returns back to exit_thread()). This

 * could race with rmmod in a preemptive UP kernel, leading to

 * code running in freed memory. The race also exists in SMP

 * kernels, but the time window is extremely small.

 *

 * Since exit() isn't performance-critical, we wrap the call to

 * vperfctr_stub.exit() with code to increment the module's use

 * count before the call, and decrement it again afterwards. Thus,

 * the final drop to zero occurs here and not in the module itself.

 * (All other code paths that drop the use count do so via a file

 * object, and VFS also refcounts the module.)

 */

void _vperfctr_exit(struct vperfctr *perfctr)

{

	__module_get(vperfctr_stub.owner);

	vperfctr_stub.exit(perfctr);

	module_put(vperfctr_stub.owner);

}

/* __vperfctr_flush() is a conditional __vperfctr_exit(),

 * so it needs the same protection.

 */

void _vperfctr_flush(struct vperfctr *perfctr)

{

	__module_get(vperfctr_stub.owner);

	vperfctr_stub.flush(perfctr);

	module_put(vperfctr_stub.owner);

}

EXPORT_SYMBOL(vperfctr_stub);

EXPORT_SYMBOL___put_task_struct;

#if !defined(CONFIG_UTRACE)

#include <linux/mm.h>

#include <linux/ptrace.h>

EXPORT_SYMBOL(ptrace_check_attach);

#endif