ip_vs_sched.c

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/*
 * IPVS         An implementation of the IP virtual server support for the
 *              LINUX operating system.  IPVS is now implemented as a module
 *              over the Netfilter framework. IPVS can be used to build a
 *              high-performance and highly available server based on a
 *              cluster of servers.
 *
 * Authors:     Wensong Zhang <[email protected]>
 *              Peter Kese <[email protected]>
 *
 *              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.
 *
 * Changes:
 *
 */

#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>

EXPORT_SYMBOL(ip_vs_scheduler_err);
/*
 *  IPVS scheduler list
 */
static LIST_HEAD(ip_vs_schedulers);

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


/*
 *  Bind a service with a scheduler
 */
int ip_vs_bind_scheduler(struct ip_vs_service *svc,
             struct ip_vs_scheduler *scheduler)
{
    int ret;

    svc->scheduler = scheduler;

    if (scheduler->init_service) {
        ret = scheduler->init_service(svc);
        if (ret) {
            pr_err("%s(): init error\n", __func__);
            return ret;
        }
    }

    return 0;
}


/*
 *  Unbind a service with its scheduler
 */
int ip_vs_unbind_scheduler(struct ip_vs_service *svc)
{
    struct ip_vs_scheduler *sched = svc->scheduler;

    if (!sched)
        return 0;

    if (sched->done_service) {
        if (sched->done_service(svc) != 0) {
            pr_err("%s(): done error\n", __func__);
            return -EINVAL;
        }
    }

    svc->scheduler = NULL;
    return 0;
}


/*
 *  Get scheduler in the scheduler list by name
 */
static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
{
    struct ip_vs_scheduler *sched;

    IP_VS_DBG(2, "%s(): sched_name \"%s\"\n", __func__, sched_name);

    spin_lock_bh(&ip_vs_sched_lock);

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

    spin_unlock_bh(&ip_vs_sched_lock);
    return NULL;
}


/*
 *  Lookup scheduler and try to load it if it doesn't exist
 */
struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
{
    struct ip_vs_scheduler *sched;

    /*
     *  Search for the scheduler by sched_name
     */
    sched = ip_vs_sched_getbyname(sched_name);

    /*
     *  If scheduler not found, load the module and search again
     */
    if (sched == NULL) {
        request_module("ip_vs_%s", sched_name);
        sched = ip_vs_sched_getbyname(sched_name);
    }

    return sched;
}

void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
{
    if (scheduler && scheduler->module)
        module_put(scheduler->module);
}

/*
 * Common error output helper for schedulers
 */

void ip_vs_scheduler_err(struct ip_vs_service *svc, const char *msg)
{
    if (svc->fwmark) {
        IP_VS_ERR_RL("%s: FWM %u 0x%08X - %s\n",
                 svc->scheduler->name, svc->fwmark,
                 svc->fwmark, msg);
#ifdef CONFIG_IP_VS_IPV6
    } else if (svc->af == AF_INET6) {
        IP_VS_ERR_RL("%s: %s [%pI6]:%d - %s\n",
                 svc->scheduler->name,
                 ip_vs_proto_name(svc->protocol),
                 &svc->addr.in6, ntohs(svc->port), msg);
#endif
    } else {
        IP_VS_ERR_RL("%s: %s %pI4:%d - %s\n",
                 svc->scheduler->name,
                 ip_vs_proto_name(svc->protocol),
                 &svc->addr.ip, ntohs(svc->port), msg);
    }
}

/*
 *  Register a scheduler in the scheduler list
 */
int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
{
    struct ip_vs_scheduler *sched;

    if (!scheduler) {
        pr_err("%s(): NULL arg\n", __func__);
        return -EINVAL;
    }

    if (!scheduler->name) {
        pr_err("%s(): NULL scheduler_name\n", __func__);
        return -EINVAL;
    }

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

    spin_lock_bh(&ip_vs_sched_lock);

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

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

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

    return 0;
}


/*
 *  Unregister a scheduler from the scheduler list
 */
int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
{
    if (!scheduler) {
        pr_err("%s(): NULL arg\n", __func__);
        return -EINVAL;
    }

    spin_lock_bh(&ip_vs_sched_lock);
    if (list_empty(&scheduler->n_list)) {
        spin_unlock_bh(&ip_vs_sched_lock);
        pr_err("%s(): [%s] scheduler is not in the list. failed\n",
               __func__, scheduler->name);
        return -EINVAL;
    }

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

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

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

    return 0;
}