res_counter.c

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/*
 * resource cgroups
 *
 * Copyright 2007 OpenVZ SWsoft Inc
 *
 * Author: Pavel Emelianov <[email protected]>
 *
 */

#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,
                  bool force)
{
    int ret = 0;

    if (counter->usage + val > counter->limit) {
        counter->failcnt++;
        ret = -ENOMEM;
        if (!force)
            return ret;
    }

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

static int __res_counter_charge(struct res_counter *counter, unsigned long val,
                struct res_counter **limit_fail_at, bool force)
{
    int ret, r;
    unsigned long flags;
    struct res_counter *c, *u;

    r = ret = 0;
    *limit_fail_at = NULL;
    local_irq_save(flags);
    for (c = counter; c != NULL; c = c->parent) {
        spin_lock(&c->lock);
        r = res_counter_charge_locked(c, val, force);
        spin_unlock(&c->lock);
        if (r < 0 && !ret) {
            ret = r;
            *limit_fail_at = c;
            if (!force)
                break;
        }
    }

    if (ret < 0 && !force) {
        for (u = counter; u != c; u = u->parent) {
            spin_lock(&u->lock);
            res_counter_uncharge_locked(u, val);
            spin_unlock(&u->lock);
        }
    }
    local_irq_restore(flags);

    return ret;
}

int res_counter_charge(struct res_counter *counter, unsigned long val,
            struct res_counter **limit_fail_at)
{
    return __res_counter_charge(counter, val, limit_fail_at, false);
}

int res_counter_charge_nofail(struct res_counter *counter, unsigned long val,
                  struct res_counter **limit_fail_at)
{
    return __res_counter_charge(counter, val, limit_fail_at, true);
}

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_until(struct res_counter *counter,
                struct res_counter *top,
                unsigned long val)
{
    unsigned long flags;
    struct res_counter *c;

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

void res_counter_uncharge(struct res_counter *counter, unsigned long val)
{
    res_counter_uncharge_until(counter, NULL, val);
}

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);
}

#if BITS_PER_LONG == 32
u64 res_counter_read_u64(struct res_counter *counter, int member)
{
    unsigned long flags;
    u64 ret;

    spin_lock_irqsave(&counter->lock, flags);
    ret = *res_counter_member(counter, member);
    spin_unlock_irqrestore(&counter->lock, flags);

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

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;
    }

    *res = memparse(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;
}