ip_vs_pe.c

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#define KMSG_COMPONENT "IPVS"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <asm/string.h>
#include <linux/kmod.h>
#include <linux/sysctl.h>

#include <net/ip_vs.h>

/* IPVS pe list */
static LIST_HEAD(ip_vs_pe);

/* lock for service table */
static DEFINE_SPINLOCK(ip_vs_pe_lock);

/* Bind a service with a pe */
void ip_vs_bind_pe(struct ip_vs_service *svc, struct ip_vs_pe *pe)
{
    svc->pe = pe;
}

/* Unbind a service from its pe */
void ip_vs_unbind_pe(struct ip_vs_service *svc)
{
    svc->pe = NULL;
}

/* Get pe in the pe list by name */
struct ip_vs_pe *__ip_vs_pe_getbyname(const char *pe_name)
{
    struct ip_vs_pe *pe;

    IP_VS_DBG(10, "%s(): pe_name \"%s\"\n", __func__,
          pe_name);

    spin_lock_bh(&ip_vs_pe_lock);

    list_for_each_entry(pe, &ip_vs_pe, n_list) {
        /* Test and get the modules atomically */
        if (pe->module &&
            !try_module_get(pe->module)) {
            /* This pe is just deleted */
            continue;
        }
        if (strcmp(pe_name, pe->name)==0) {
            /* HIT */
            spin_unlock_bh(&ip_vs_pe_lock);
            return pe;
        }
        if (pe->module)
            module_put(pe->module);
    }

    spin_unlock_bh(&ip_vs_pe_lock);
    return NULL;
}

/* Lookup pe and try to load it if it doesn't exist */
struct ip_vs_pe *ip_vs_pe_getbyname(const char *name)
{
    struct ip_vs_pe *pe;

    /* Search for the pe by name */
    pe = __ip_vs_pe_getbyname(name);

    /* If pe not found, load the module and search again */
    if (!pe) {
        request_module("ip_vs_pe_%s", name);
        pe = __ip_vs_pe_getbyname(name);
    }

    return pe;
}

/* Register a pe in the pe list */
int register_ip_vs_pe(struct ip_vs_pe *pe)
{
    struct ip_vs_pe *tmp;

    /* increase the module use count */
    ip_vs_use_count_inc();

    spin_lock_bh(&ip_vs_pe_lock);

    if (!list_empty(&pe->n_list)) {
        spin_unlock_bh(&ip_vs_pe_lock);
        ip_vs_use_count_dec();
        pr_err("%s(): [%s] pe already linked\n",
               __func__, pe->name);
        return -EINVAL;
    }

    /* Make sure that the pe with this name doesn't exist
     * in the pe list.
     */
    list_for_each_entry(tmp, &ip_vs_pe, n_list) {
        if (strcmp(tmp->name, pe->name) == 0) {
            spin_unlock_bh(&ip_vs_pe_lock);
            ip_vs_use_count_dec();
            pr_err("%s(): [%s] pe already existed "
                   "in the system\n", __func__, pe->name);
            return -EINVAL;
        }
    }
    /* Add it into the d-linked pe list */
    list_add(&pe->n_list, &ip_vs_pe);
    spin_unlock_bh(&ip_vs_pe_lock);

    pr_info("[%s] pe registered.\n", pe->name);

    return 0;
}
EXPORT_SYMBOL_GPL(register_ip_vs_pe);

/* Unregister a pe from the pe list */
int unregister_ip_vs_pe(struct ip_vs_pe *pe)
{
    spin_lock_bh(&ip_vs_pe_lock);
    if (list_empty(&pe->n_list)) {
        spin_unlock_bh(&ip_vs_pe_lock);
        pr_err("%s(): [%s] pe is not in the list. failed\n",
               __func__, pe->name);
        return -EINVAL;
    }

    /* Remove it from the d-linked pe list */
    list_del(&pe->n_list);
    spin_unlock_bh(&ip_vs_pe_lock);

    /* decrease the module use count */
    ip_vs_use_count_dec();

    pr_info("[%s] pe unregistered.\n", pe->name);

    return 0;
}
EXPORT_SYMBOL_GPL(unregister_ip_vs_pe);