/* delayacct.h - per-task delay accounting
*
* Copyright (C) Shailabh Nagar, IBM Corp. 2006
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU General Public License for more details.
*
*/

#ifndef _LINUX_DELAYACCT_H
#define _LINUX_DELAYACCT_H

#include <linux/sched.h>
#include <linux/slab.h>

/*
* Per-task flags relevant to delay accounting
* maintained privately to avoid exhausting similar flags in sched.h:PF_*
* Used to set current->delays->flags
*/
#define DELAYACCT_PF_SWAPIN 0x00000001 /* I am doing a swapin */
#define DELAYACCT_PF_BLKIO 0x00000002 /* I am waiting on IO */

#ifdef CONFIG_TASK_DELAY_ACCT

extern int delayacct_on; /* Delay accounting turned on/off */
extern struct kmem_cache *delayacct_cache;
extern void delayacct_init(void);
extern void __delayacct_tsk_init(struct task_struct *);
extern void __delayacct_tsk_exit(struct task_struct *);
extern void __delayacct_blkio_start(void);
extern void __delayacct_blkio_end(void);
extern int __delayacct_add_tsk(struct taskstats *, struct task_struct *);
extern __u64 __delayacct_blkio_ticks(struct task_struct *);
extern void __delayacct_freepages_start(void);
extern void __delayacct_freepages_end(void);

static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
{
if (p->delays)
return (p->delays->flags & DELAYACCT_PF_BLKIO);
else
return 0;
}

static inline void delayacct_set_flag(int flag)
{
if (current->delays)
current->delays->flags |= flag;
}

static inline void delayacct_clear_flag(int flag)
{
if (current->delays)
current->delays->flags &= ~flag;
}

static inline void delayacct_tsk_init(struct task_struct *tsk)
{
/* reinitialize in case parent's non-null pointer was dup'ed*/
tsk->delays = NULL;
if (delayacct_on)
__delayacct_tsk_init(tsk);
}

/* Free tsk->delays. Called from bad fork and __put_task_struct
* where there's no risk of tsk->delays being accessed elsewhere
*/
static inline void delayacct_tsk_free(struct task_struct *tsk)
{
if (tsk->delays)
kmem_cache_free(delayacct_cache, tsk->delays);
tsk->delays = NULL;
}

static inline void delayacct_blkio_start(void)
{
delayacct_set_flag(DELAYACCT_PF_BLKIO);
if (current->delays)
__delayacct_blkio_start();
}

static inline void delayacct_blkio_end(void)
{
if (current->delays)
__delayacct_blkio_end();
delayacct_clear_flag(DELAYACCT_PF_BLKIO);
}

static inline int delayacct_add_tsk(struct taskstats *d,
struct task_struct *tsk)
{
if (!delayacct_on || !tsk->delays)
return 0;
return __delayacct_add_tsk(d, tsk);
}

static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
{
if (tsk->delays)
return __delayacct_blkio_ticks(tsk);
return 0;
}

static inline void delayacct_freepages_start(void)
{
if (current->delays)
__delayacct_freepages_start();
}

static inline void delayacct_freepages_end(void)
{
if (current->delays)
__delayacct_freepages_end();
}

#else
static inline void delayacct_set_flag(int flag)
{}
static inline void delayacct_clear_flag(int flag)
{}
static inline void delayacct_init(void)
{}
static inline void delayacct_tsk_init(struct task_struct *tsk)
{}
static inline void delayacct_tsk_free(struct task_struct *tsk)
{}
static inline void delayacct_blkio_start(void)
{}
static inline void delayacct_blkio_end(void)
{}
static inline int delayacct_add_tsk(struct taskstats *d,
struct task_struct *tsk)
{ return 0; }
static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
{ return 0; }
static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
{ return 0; }
static inline void delayacct_freepages_start(void)
{}
static inline void delayacct_freepages_end(void)
{}

#endif /* CONFIG_TASK_DELAY_ACCT */

#endif