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tag: v2.6.35-rc6
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/*
* resource cgroups
*
* Copyright 2007 OpenVZ SWsoft Inc
*
* Author: Pavel Emelianov <xemul@openvz.org>
*
*/

#include <linux/types.h>
#include <linux/parser.h>
#include <linux/fs.h>
#include <linux/res_counter.h>
#include <linux/uaccess.h>
#include <linux/mm.h>

void res_counter_init(struct res_counter *counter, struct res_counter *parent)
{
spin_lock_init(&counter->lock);
counter->limit = RESOURCE_MAX;
counter->soft_limit = RESOURCE_MAX;
counter->parent = parent;
}

int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
{
if (counter->usage + val > counter->limit) {
counter->failcnt++;
return -ENOMEM;
}

counter->usage += val;
if (counter->usage > counter->max_usage)
counter->max_usage = counter->usage;
return 0;
}

int res_counter_charge(struct res_counter *counter, unsigned long val,
struct res_counter **limit_fail_at)
{
int ret;
unsigned long flags;
struct res_counter *c, *u;

*limit_fail_at = NULL;
local_irq_save(flags);
for (c = counter; c != NULL; c = c->parent) {
spin_lock(&c->lock);
ret = res_counter_charge_locked(c, val);
spin_unlock(&c->lock);
if (ret < 0) {
*limit_fail_at = c;
goto undo;
}
}
ret = 0;
goto done;
undo:
for (u = counter; u != c; u = u->parent) {
spin_lock(&u->lock);
res_counter_uncharge_locked(u, val);
spin_unlock(&u->lock);
}
done:
local_irq_restore(flags);
return ret;
}

void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
{
if (WARN_ON(counter->usage < val))
val = counter->usage;

counter->usage -= val;
}

void res_counter_uncharge(struct res_counter *counter, unsigned long val)
{
unsigned long flags;
struct res_counter *c;

local_irq_save(flags);
for (c = counter; c != NULL; c = c->parent) {
spin_lock(&c->lock);
res_counter_uncharge_locked(c, val);
spin_unlock(&c->lock);
}
local_irq_restore(flags);
}


static inline unsigned long long *
res_counter_member(struct res_counter *counter, int member)
{
switch (member) {
case RES_USAGE:
return &counter->usage;
case RES_MAX_USAGE:
return &counter->max_usage;
case RES_LIMIT:
return &counter->limit;
case RES_FAILCNT:
return &counter->failcnt;
case RES_SOFT_LIMIT:
return &counter->soft_limit;
};

BUG();
return NULL;
}

ssize_t res_counter_read(struct res_counter *counter, int member,
const char __user *userbuf, size_t nbytes, loff_t *pos,
int (*read_strategy)(unsigned long long val, char *st_buf))
{
unsigned long long *val;
char buf[64], *s;

s = buf;
val = res_counter_member(counter, member);
if (read_strategy)
s += read_strategy(*val, s);
else
s += sprintf(s, "%llu\n", *val);
return simple_read_from_buffer((void __user *)userbuf, nbytes,
pos, buf, s - buf);
}

u64 res_counter_read_u64(struct res_counter *counter, int member)
{
return *res_counter_member(counter, member);
}

int res_counter_memparse_write_strategy(const char *buf,
unsigned long long *res)
{
char *end;

/* return RESOURCE_MAX(unlimited) if "-1" is specified */
if (*buf == '-') {
*res = simple_strtoull(buf + 1, &end, 10);
if (*res != 1 || *end != '\0')
return -EINVAL;
*res = RESOURCE_MAX;
return 0;
}

/* FIXME - make memparse() take const char* args */
*res = memparse((char *)buf, &end);
if (*end != '\0')
return -EINVAL;

*res = PAGE_ALIGN(*res);
return 0;
}

int res_counter_write(struct res_counter *counter, int member,
const char *buf, write_strategy_fn write_strategy)
{
char *end;
unsigned long flags;
unsigned long long tmp, *val;

if (write_strategy) {
if (write_strategy(buf, &tmp))
return -EINVAL;
} else {
tmp = simple_strtoull(buf, &end, 10);
if (*end != '\0')
return -EINVAL;
}
spin_lock_irqsave(&counter->lock, flags);
val = res_counter_member(counter, member);
*val = tmp;
spin_unlock_irqrestore(&counter->lock, flags);
return 0;
}
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