tcp_memcontrol.c

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#include <net/tcp.h>
#include <net/tcp_memcontrol.h>
#include <net/sock.h>
#include <net/ip.h>
#include <linux/nsproxy.h>
#include <linux/memcontrol.h>
#include <linux/module.h>

static inline struct tcp_memcontrol *tcp_from_cgproto(struct cg_proto *cg_proto)
{
    return container_of(cg_proto, struct tcp_memcontrol, cg_proto);
}

static void memcg_tcp_enter_memory_pressure(struct sock *sk)
{
    if (sk->sk_cgrp->memory_pressure)
        *sk->sk_cgrp->memory_pressure = 1;
}
EXPORT_SYMBOL(memcg_tcp_enter_memory_pressure);

int tcp_init_cgroup(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
{
    /*
     * The root cgroup does not use res_counters, but rather,
     * rely on the data already collected by the network
     * subsystem
     */
    struct res_counter *res_parent = NULL;
    struct cg_proto *cg_proto, *parent_cg;
    struct tcp_memcontrol *tcp;
    struct mem_cgroup *parent = parent_mem_cgroup(memcg);
    struct net *net = current->nsproxy->net_ns;

    cg_proto = tcp_prot.proto_cgroup(memcg);
    if (!cg_proto)
        return 0;

    tcp = tcp_from_cgproto(cg_proto);

    tcp->tcp_prot_mem[0] = net->ipv4.sysctl_tcp_mem[0];
    tcp->tcp_prot_mem[1] = net->ipv4.sysctl_tcp_mem[1];
    tcp->tcp_prot_mem[2] = net->ipv4.sysctl_tcp_mem[2];
    tcp->tcp_memory_pressure = 0;

    parent_cg = tcp_prot.proto_cgroup(parent);
    if (parent_cg)
        res_parent = parent_cg->memory_allocated;

    res_counter_init(&tcp->tcp_memory_allocated, res_parent);
    percpu_counter_init(&tcp->tcp_sockets_allocated, 0);

    cg_proto->enter_memory_pressure = memcg_tcp_enter_memory_pressure;
    cg_proto->memory_pressure = &tcp->tcp_memory_pressure;
    cg_proto->sysctl_mem = tcp->tcp_prot_mem;
    cg_proto->memory_allocated = &tcp->tcp_memory_allocated;
    cg_proto->sockets_allocated = &tcp->tcp_sockets_allocated;
    cg_proto->memcg = memcg;

    return 0;
}
EXPORT_SYMBOL(tcp_init_cgroup);

void tcp_destroy_cgroup(struct mem_cgroup *memcg)
{
    struct cg_proto *cg_proto;
    struct tcp_memcontrol *tcp;
    u64 val;

    cg_proto = tcp_prot.proto_cgroup(memcg);
    if (!cg_proto)
        return;

    tcp = tcp_from_cgproto(cg_proto);
    percpu_counter_destroy(&tcp->tcp_sockets_allocated);

    val = res_counter_read_u64(&tcp->tcp_memory_allocated, RES_LIMIT);
}
EXPORT_SYMBOL(tcp_destroy_cgroup);

static int tcp_update_limit(struct mem_cgroup *memcg, u64 val)
{
    struct net *net = current->nsproxy->net_ns;
    struct tcp_memcontrol *tcp;
    struct cg_proto *cg_proto;
    u64 old_lim;
    int i;
    int ret;

    cg_proto = tcp_prot.proto_cgroup(memcg);
    if (!cg_proto)
        return -EINVAL;

    if (val > RESOURCE_MAX)
        val = RESOURCE_MAX;

    tcp = tcp_from_cgproto(cg_proto);

    old_lim = res_counter_read_u64(&tcp->tcp_memory_allocated, RES_LIMIT);
    ret = res_counter_set_limit(&tcp->tcp_memory_allocated, val);
    if (ret)
        return ret;

    for (i = 0; i < 3; i++)
        tcp->tcp_prot_mem[i] = min_t(long, val >> PAGE_SHIFT,
                         net->ipv4.sysctl_tcp_mem[i]);

    if (val == RESOURCE_MAX)
        clear_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags);
    else if (val != RESOURCE_MAX) {
        /*
         * The active bit needs to be written after the static_key
         * update. This is what guarantees that the socket activation
         * function is the last one to run. See sock_update_memcg() for
         * details, and note that we don't mark any socket as belonging
         * to this memcg until that flag is up.
         *
         * We need to do this, because static_keys will span multiple
         * sites, but we can't control their order. If we mark a socket
         * as accounted, but the accounting functions are not patched in
         * yet, we'll lose accounting.
         *
         * We never race with the readers in sock_update_memcg(),
         * because when this value change, the code to process it is not
         * patched in yet.
         *
         * The activated bit is used to guarantee that no two writers
         * will do the update in the same memcg. Without that, we can't
         * properly shutdown the static key.
         */
        if (!test_and_set_bit(MEMCG_SOCK_ACTIVATED, &cg_proto->flags))
            static_key_slow_inc(&memcg_socket_limit_enabled);
        set_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags);
    }

    return 0;
}

static int tcp_cgroup_write(struct cgroup *cont, struct cftype *cft,
                const char *buffer)
{
    struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
    unsigned long long val;
    int ret = 0;

    switch (cft->private) {
    case RES_LIMIT:
        /* see memcontrol.c */
        ret = res_counter_memparse_write_strategy(buffer, &val);
        if (ret)
            break;
        ret = tcp_update_limit(memcg, val);
        break;
    default:
        ret = -EINVAL;
        break;
    }
    return ret;
}

static u64 tcp_read_stat(struct mem_cgroup *memcg, int type, u64 default_val)
{
    struct tcp_memcontrol *tcp;
    struct cg_proto *cg_proto;

    cg_proto = tcp_prot.proto_cgroup(memcg);
    if (!cg_proto)
        return default_val;

    tcp = tcp_from_cgproto(cg_proto);
    return res_counter_read_u64(&tcp->tcp_memory_allocated, type);
}

static u64 tcp_read_usage(struct mem_cgroup *memcg)
{
    struct tcp_memcontrol *tcp;
    struct cg_proto *cg_proto;

    cg_proto = tcp_prot.proto_cgroup(memcg);
    if (!cg_proto)
        return atomic_long_read(&tcp_memory_allocated) << PAGE_SHIFT;

    tcp = tcp_from_cgproto(cg_proto);
    return res_counter_read_u64(&tcp->tcp_memory_allocated, RES_USAGE);
}

static u64 tcp_cgroup_read(struct cgroup *cont, struct cftype *cft)
{
    struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
    u64 val;

    switch (cft->private) {
    case RES_LIMIT:
        val = tcp_read_stat(memcg, RES_LIMIT, RESOURCE_MAX);
        break;
    case RES_USAGE:
        val = tcp_read_usage(memcg);
        break;
    case RES_FAILCNT:
    case RES_MAX_USAGE:
        val = tcp_read_stat(memcg, cft->private, 0);
        break;
    default:
        BUG();
    }
    return val;
}

static int tcp_cgroup_reset(struct cgroup *cont, unsigned int event)
{
    struct mem_cgroup *memcg;
    struct tcp_memcontrol *tcp;
    struct cg_proto *cg_proto;

    memcg = mem_cgroup_from_cont(cont);
    cg_proto = tcp_prot.proto_cgroup(memcg);
    if (!cg_proto)
        return 0;
    tcp = tcp_from_cgproto(cg_proto);

    switch (event) {
    case RES_MAX_USAGE:
        res_counter_reset_max(&tcp->tcp_memory_allocated);
        break;
    case RES_FAILCNT:
        res_counter_reset_failcnt(&tcp->tcp_memory_allocated);
        break;
    }

    return 0;
}

unsigned long long tcp_max_memory(const struct mem_cgroup *memcg)
{
    struct tcp_memcontrol *tcp;
    struct cg_proto *cg_proto;

    cg_proto = tcp_prot.proto_cgroup((struct mem_cgroup *)memcg);
    if (!cg_proto)
        return 0;

    tcp = tcp_from_cgproto(cg_proto);
    return res_counter_read_u64(&tcp->tcp_memory_allocated, RES_LIMIT);
}

void tcp_prot_mem(struct mem_cgroup *memcg, long val, int idx)
{
    struct tcp_memcontrol *tcp;
    struct cg_proto *cg_proto;

    cg_proto = tcp_prot.proto_cgroup(memcg);
    if (!cg_proto)
        return;

    tcp = tcp_from_cgproto(cg_proto);

    tcp->tcp_prot_mem[idx] = val;
}

static struct cftype tcp_files[] = {
    {
        .name = "kmem.tcp.limit_in_bytes",
        .write_string = tcp_cgroup_write,
        .read_u64 = tcp_cgroup_read,
        .private = RES_LIMIT,
    },
    {
        .name = "kmem.tcp.usage_in_bytes",
        .read_u64 = tcp_cgroup_read,
        .private = RES_USAGE,
    },
    {
        .name = "kmem.tcp.failcnt",
        .private = RES_FAILCNT,
        .trigger = tcp_cgroup_reset,
        .read_u64 = tcp_cgroup_read,
    },
    {
        .name = "kmem.tcp.max_usage_in_bytes",
        .private = RES_MAX_USAGE,
        .trigger = tcp_cgroup_reset,
        .read_u64 = tcp_cgroup_read,
    },
    { } /* terminate */
};

static int __init tcp_memcontrol_init(void)
{
    WARN_ON(cgroup_add_cftypes(&mem_cgroup_subsys, tcp_files));
    return 0;
}
__initcall(tcp_memcontrol_init);