root/net/atm/mpoa_caches.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/types.h>
#include <linux/atmmpc.h>
#include <linux/slab.h>
#include <linux/time.h>

#include "mpoa_caches.h"
#include "mpc.h"

/*
 * mpoa_caches.c: Implementation of ingress and egress cache
 * handling functions
 */

#if 0
#define dprintk(format, args...)                                        \
        printk(KERN_DEBUG "mpoa:%s: " format, __FILE__, ##args)  /* debug */
#else
#define dprintk(format, args...)                                        \
        do { if (0)                                                     \
                printk(KERN_DEBUG "mpoa:%s: " format, __FILE__, ##args);\
        } while (0)
#endif

#if 0
#define ddprintk(format, args...)                                       \
        printk(KERN_DEBUG "mpoa:%s: " format, __FILE__, ##args)  /* debug */
#else
#define ddprintk(format, args...)                                       \
        do { if (0)                                                     \
                printk(KERN_DEBUG "mpoa:%s: " format, __FILE__, ##args);\
        } while (0)
#endif

static in_cache_entry *in_cache_get(__be32 dst_ip,
                                    struct mpoa_client *client)
{
        in_cache_entry *entry;

        read_lock_bh(&client->ingress_lock);
        entry = client->in_cache;
        while (entry != NULL) {
                if (entry->ctrl_info.in_dst_ip == dst_ip) {
                        refcount_inc(&entry->use);
                        read_unlock_bh(&client->ingress_lock);
                        return entry;
                }
                entry = entry->next;
        }
        read_unlock_bh(&client->ingress_lock);

        return NULL;
}

static in_cache_entry *in_cache_get_with_mask(__be32 dst_ip,
                                              struct mpoa_client *client,
                                              __be32 mask)
{
        in_cache_entry *entry;

        read_lock_bh(&client->ingress_lock);
        entry = client->in_cache;
        while (entry != NULL) {
                if ((entry->ctrl_info.in_dst_ip & mask) == (dst_ip & mask)) {
                        refcount_inc(&entry->use);
                        read_unlock_bh(&client->ingress_lock);
                        return entry;
                }
                entry = entry->next;
        }
        read_unlock_bh(&client->ingress_lock);

        return NULL;

}

static in_cache_entry *in_cache_get_by_vcc(struct atm_vcc *vcc,
                                           struct mpoa_client *client)
{
        in_cache_entry *entry;

        read_lock_bh(&client->ingress_lock);
        entry = client->in_cache;
        while (entry != NULL) {
                if (entry->shortcut == vcc) {
                        refcount_inc(&entry->use);
                        read_unlock_bh(&client->ingress_lock);
                        return entry;
                }
                entry = entry->next;
        }
        read_unlock_bh(&client->ingress_lock);

        return NULL;
}

static in_cache_entry *in_cache_add_entry(__be32 dst_ip,
                                          struct mpoa_client *client)
{
        in_cache_entry *entry = kzalloc_obj(in_cache_entry);

        if (entry == NULL) {
                pr_info("mpoa: mpoa_caches.c: new_in_cache_entry: out of memory\n");
                return NULL;
        }

        dprintk("adding an ingress entry, ip = %pI4\n", &dst_ip);

        refcount_set(&entry->use, 1);
        dprintk("new_in_cache_entry: about to lock\n");
        write_lock_bh(&client->ingress_lock);
        entry->next = client->in_cache;
        entry->prev = NULL;
        if (client->in_cache != NULL)
                client->in_cache->prev = entry;
        client->in_cache = entry;

        memcpy(entry->MPS_ctrl_ATM_addr, client->mps_ctrl_addr, ATM_ESA_LEN);
        entry->ctrl_info.in_dst_ip = dst_ip;
        entry->time = ktime_get_seconds();
        entry->retry_time = client->parameters.mpc_p4;
        entry->count = 1;
        entry->entry_state = INGRESS_INVALID;
        entry->ctrl_info.holding_time = HOLDING_TIME_DEFAULT;
        refcount_inc(&entry->use);

        write_unlock_bh(&client->ingress_lock);
        dprintk("new_in_cache_entry: unlocked\n");

        return entry;
}

static int cache_hit(in_cache_entry *entry, struct mpoa_client *mpc)
{
        struct atm_mpoa_qos *qos;
        struct k_message msg;

        entry->count++;
        if (entry->entry_state == INGRESS_RESOLVED && entry->shortcut != NULL)
                return OPEN;

        if (entry->entry_state == INGRESS_REFRESHING) {
                if (entry->count > mpc->parameters.mpc_p1) {
                        msg.type = SND_MPOA_RES_RQST;
                        msg.content.in_info = entry->ctrl_info;
                        memcpy(msg.MPS_ctrl, mpc->mps_ctrl_addr, ATM_ESA_LEN);
                        qos = atm_mpoa_search_qos(entry->ctrl_info.in_dst_ip);
                        if (qos != NULL)
                                msg.qos = qos->qos;
                        msg_to_mpoad(&msg, mpc);
                        entry->reply_wait = ktime_get_seconds();
                        entry->entry_state = INGRESS_RESOLVING;
                }
                if (entry->shortcut != NULL)
                        return OPEN;
                return CLOSED;
        }

        if (entry->entry_state == INGRESS_RESOLVING && entry->shortcut != NULL)
                return OPEN;

        if (entry->count > mpc->parameters.mpc_p1 &&
            entry->entry_state == INGRESS_INVALID) {
                dprintk("(%s) threshold exceeded for ip %pI4, sending MPOA res req\n",
                        mpc->dev->name, &entry->ctrl_info.in_dst_ip);
                entry->entry_state = INGRESS_RESOLVING;
                msg.type = SND_MPOA_RES_RQST;
                memcpy(msg.MPS_ctrl, mpc->mps_ctrl_addr, ATM_ESA_LEN);
                msg.content.in_info = entry->ctrl_info;
                qos = atm_mpoa_search_qos(entry->ctrl_info.in_dst_ip);
                if (qos != NULL)
                        msg.qos = qos->qos;
                msg_to_mpoad(&msg, mpc);
                entry->reply_wait = ktime_get_seconds();
        }

        return CLOSED;
}

static void in_cache_put(in_cache_entry *entry)
{
        if (refcount_dec_and_test(&entry->use)) {
                kfree_sensitive(entry);
        }
}

/*
 * This should be called with write lock on
 */
static void in_cache_remove_entry(in_cache_entry *entry,
                                  struct mpoa_client *client)
{
        struct atm_vcc *vcc;
        struct k_message msg;

        vcc = entry->shortcut;
        dprintk("removing an ingress entry, ip = %pI4\n",
                &entry->ctrl_info.in_dst_ip);

        if (entry->prev != NULL)
                entry->prev->next = entry->next;
        else
                client->in_cache = entry->next;
        if (entry->next != NULL)
                entry->next->prev = entry->prev;
        client->in_ops->put(entry);
        if (client->in_cache == NULL && client->eg_cache == NULL) {
                msg.type = STOP_KEEP_ALIVE_SM;
                msg_to_mpoad(&msg, client);
        }

        /* Check if the egress side still uses this VCC */
        if (vcc != NULL) {
                eg_cache_entry *eg_entry = client->eg_ops->get_by_vcc(vcc,
                                                                      client);
                if (eg_entry != NULL) {
                        client->eg_ops->put(eg_entry);
                        return;
                }
                vcc_release_async(vcc, -EPIPE);
        }
}

/* Call this every MPC-p2 seconds... Not exactly correct solution,
   but an easy one... */
static void clear_count_and_expired(struct mpoa_client *client)
{
        in_cache_entry *entry, *next_entry;
        time64_t now;

        now = ktime_get_seconds();

        write_lock_bh(&client->ingress_lock);
        entry = client->in_cache;
        while (entry != NULL) {
                entry->count = 0;
                next_entry = entry->next;
                if ((now - entry->time) > entry->ctrl_info.holding_time) {
                        dprintk("holding time expired, ip = %pI4\n",
                                &entry->ctrl_info.in_dst_ip);
                        client->in_ops->remove_entry(entry, client);
                }
                entry = next_entry;
        }
        write_unlock_bh(&client->ingress_lock);
}

/* Call this every MPC-p4 seconds. */
static void check_resolving_entries(struct mpoa_client *client)
{

        struct atm_mpoa_qos *qos;
        in_cache_entry *entry;
        time64_t now;
        struct k_message msg;

        now = ktime_get_seconds();

        read_lock_bh(&client->ingress_lock);
        entry = client->in_cache;
        while (entry != NULL) {
                if (entry->entry_state == INGRESS_RESOLVING) {

                        if ((now - entry->hold_down)
                                        < client->parameters.mpc_p6) {
                                entry = entry->next;    /* Entry in hold down */
                                continue;
                        }
                        if ((now - entry->reply_wait) > entry->retry_time) {
                                entry->retry_time = MPC_C1 * (entry->retry_time);
                                /*
                                 * Retry time maximum exceeded,
                                 * put entry in hold down.
                                 */
                                if (entry->retry_time > client->parameters.mpc_p5) {
                                        entry->hold_down = ktime_get_seconds();
                                        entry->retry_time = client->parameters.mpc_p4;
                                        entry = entry->next;
                                        continue;
                                }
                                /* Ask daemon to send a resolution request. */
                                memset(&entry->hold_down, 0, sizeof(time64_t));
                                msg.type = SND_MPOA_RES_RTRY;
                                memcpy(msg.MPS_ctrl, client->mps_ctrl_addr, ATM_ESA_LEN);
                                msg.content.in_info = entry->ctrl_info;
                                qos = atm_mpoa_search_qos(entry->ctrl_info.in_dst_ip);
                                if (qos != NULL)
                                        msg.qos = qos->qos;
                                msg_to_mpoad(&msg, client);
                                entry->reply_wait = ktime_get_seconds();
                        }
                }
                entry = entry->next;
        }
        read_unlock_bh(&client->ingress_lock);
}

/* Call this every MPC-p5 seconds. */
static void refresh_entries(struct mpoa_client *client)
{
        time64_t now;
        struct in_cache_entry *entry = client->in_cache;

        ddprintk("refresh_entries\n");
        now = ktime_get_seconds();

        read_lock_bh(&client->ingress_lock);
        while (entry != NULL) {
                if (entry->entry_state == INGRESS_RESOLVED) {
                        if (!(entry->refresh_time))
                                entry->refresh_time = (2 * (entry->ctrl_info.holding_time))/3;
                        if ((now - entry->reply_wait) >
                            entry->refresh_time) {
                                dprintk("refreshing an entry.\n");
                                entry->entry_state = INGRESS_REFRESHING;

                        }
                }
                entry = entry->next;
        }
        read_unlock_bh(&client->ingress_lock);
}

static void in_destroy_cache(struct mpoa_client *mpc)
{
        write_lock_irq(&mpc->ingress_lock);
        while (mpc->in_cache != NULL)
                mpc->in_ops->remove_entry(mpc->in_cache, mpc);
        write_unlock_irq(&mpc->ingress_lock);
}

static eg_cache_entry *eg_cache_get_by_cache_id(__be32 cache_id,
                                                struct mpoa_client *mpc)
{
        eg_cache_entry *entry;

        read_lock_irq(&mpc->egress_lock);
        entry = mpc->eg_cache;
        while (entry != NULL) {
                if (entry->ctrl_info.cache_id == cache_id) {
                        refcount_inc(&entry->use);
                        read_unlock_irq(&mpc->egress_lock);
                        return entry;
                }
                entry = entry->next;
        }
        read_unlock_irq(&mpc->egress_lock);

        return NULL;
}

/* This can be called from any context since it saves CPU flags */
static eg_cache_entry *eg_cache_get_by_tag(__be32 tag, struct mpoa_client *mpc)
{
        unsigned long flags;
        eg_cache_entry *entry;

        read_lock_irqsave(&mpc->egress_lock, flags);
        entry = mpc->eg_cache;
        while (entry != NULL) {
                if (entry->ctrl_info.tag == tag) {
                        refcount_inc(&entry->use);
                        read_unlock_irqrestore(&mpc->egress_lock, flags);
                        return entry;
                }
                entry = entry->next;
        }
        read_unlock_irqrestore(&mpc->egress_lock, flags);

        return NULL;
}

/* This can be called from any context since it saves CPU flags */
static eg_cache_entry *eg_cache_get_by_vcc(struct atm_vcc *vcc,
                                           struct mpoa_client *mpc)
{
        unsigned long flags;
        eg_cache_entry *entry;

        read_lock_irqsave(&mpc->egress_lock, flags);
        entry = mpc->eg_cache;
        while (entry != NULL) {
                if (entry->shortcut == vcc) {
                        refcount_inc(&entry->use);
                        read_unlock_irqrestore(&mpc->egress_lock, flags);
                        return entry;
                }
                entry = entry->next;
        }
        read_unlock_irqrestore(&mpc->egress_lock, flags);

        return NULL;
}

static eg_cache_entry *eg_cache_get_by_src_ip(__be32 ipaddr,
                                              struct mpoa_client *mpc)
{
        eg_cache_entry *entry;

        read_lock_irq(&mpc->egress_lock);
        entry = mpc->eg_cache;
        while (entry != NULL) {
                if (entry->latest_ip_addr == ipaddr) {
                        refcount_inc(&entry->use);
                        read_unlock_irq(&mpc->egress_lock);
                        return entry;
                }
                entry = entry->next;
        }
        read_unlock_irq(&mpc->egress_lock);

        return NULL;
}

static void eg_cache_put(eg_cache_entry *entry)
{
        if (refcount_dec_and_test(&entry->use)) {
                kfree_sensitive(entry);
        }
}

/*
 * This should be called with write lock on
 */
static void eg_cache_remove_entry(eg_cache_entry *entry,
                                  struct mpoa_client *client)
{
        struct atm_vcc *vcc;
        struct k_message msg;

        vcc = entry->shortcut;
        dprintk("removing an egress entry.\n");
        if (entry->prev != NULL)
                entry->prev->next = entry->next;
        else
                client->eg_cache = entry->next;
        if (entry->next != NULL)
                entry->next->prev = entry->prev;
        client->eg_ops->put(entry);
        if (client->in_cache == NULL && client->eg_cache == NULL) {
                msg.type = STOP_KEEP_ALIVE_SM;
                msg_to_mpoad(&msg, client);
        }

        /* Check if the ingress side still uses this VCC */
        if (vcc != NULL) {
                in_cache_entry *in_entry = client->in_ops->get_by_vcc(vcc, client);
                if (in_entry != NULL) {
                        client->in_ops->put(in_entry);
                        return;
                }
                vcc_release_async(vcc, -EPIPE);
        }
}

static eg_cache_entry *eg_cache_add_entry(struct k_message *msg,
                                          struct mpoa_client *client)
{
        eg_cache_entry *entry = kzalloc_obj(eg_cache_entry);

        if (entry == NULL) {
                pr_info("out of memory\n");
                return NULL;
        }

        dprintk("adding an egress entry, ip = %pI4, this should be our IP\n",
                &msg->content.eg_info.eg_dst_ip);

        refcount_set(&entry->use, 1);
        dprintk("new_eg_cache_entry: about to lock\n");
        write_lock_irq(&client->egress_lock);
        entry->next = client->eg_cache;
        entry->prev = NULL;
        if (client->eg_cache != NULL)
                client->eg_cache->prev = entry;
        client->eg_cache = entry;

        memcpy(entry->MPS_ctrl_ATM_addr, client->mps_ctrl_addr, ATM_ESA_LEN);
        entry->ctrl_info = msg->content.eg_info;
        entry->time = ktime_get_seconds();
        entry->entry_state = EGRESS_RESOLVED;
        dprintk("new_eg_cache_entry cache_id %u\n",
                ntohl(entry->ctrl_info.cache_id));
        dprintk("mps_ip = %pI4\n", &entry->ctrl_info.mps_ip);
        refcount_inc(&entry->use);

        write_unlock_irq(&client->egress_lock);
        dprintk("new_eg_cache_entry: unlocked\n");

        return entry;
}

static void update_eg_cache_entry(eg_cache_entry *entry, uint16_t holding_time)
{
        entry->time = ktime_get_seconds();
        entry->entry_state = EGRESS_RESOLVED;
        entry->ctrl_info.holding_time = holding_time;
}

static void clear_expired(struct mpoa_client *client)
{
        eg_cache_entry *entry, *next_entry;
        time64_t now;
        struct k_message msg;

        now = ktime_get_seconds();

        write_lock_irq(&client->egress_lock);
        entry = client->eg_cache;
        while (entry != NULL) {
                next_entry = entry->next;
                if ((now - entry->time) > entry->ctrl_info.holding_time) {
                        msg.type = SND_EGRESS_PURGE;
                        msg.content.eg_info = entry->ctrl_info;
                        dprintk("egress_cache: holding time expired, cache_id = %u.\n",
                                ntohl(entry->ctrl_info.cache_id));
                        msg_to_mpoad(&msg, client);
                        client->eg_ops->remove_entry(entry, client);
                }
                entry = next_entry;
        }
        write_unlock_irq(&client->egress_lock);
}

static void eg_destroy_cache(struct mpoa_client *mpc)
{
        write_lock_irq(&mpc->egress_lock);
        while (mpc->eg_cache != NULL)
                mpc->eg_ops->remove_entry(mpc->eg_cache, mpc);
        write_unlock_irq(&mpc->egress_lock);
}


static const struct in_cache_ops ingress_ops = {
        .add_entry = in_cache_add_entry,
        .get = in_cache_get,
        .get_with_mask = in_cache_get_with_mask,
        .get_by_vcc = in_cache_get_by_vcc,
        .put = in_cache_put,
        .remove_entry = in_cache_remove_entry,
        .cache_hit = cache_hit,
        .clear_count = clear_count_and_expired,
        .check_resolving = check_resolving_entries,
        .refresh = refresh_entries,
        .destroy_cache = in_destroy_cache
};

static const struct eg_cache_ops egress_ops = {
        .add_entry = eg_cache_add_entry,
        .get_by_cache_id = eg_cache_get_by_cache_id,
        .get_by_tag = eg_cache_get_by_tag,
        .get_by_vcc = eg_cache_get_by_vcc,
        .get_by_src_ip = eg_cache_get_by_src_ip,
        .put = eg_cache_put,
        .remove_entry = eg_cache_remove_entry,
        .update = update_eg_cache_entry,
        .clear_expired = clear_expired,
        .destroy_cache = eg_destroy_cache
};

void atm_mpoa_init_cache(struct mpoa_client *mpc)
{
        mpc->in_ops = &ingress_ops;
        mpc->eg_ops = &egress_ops;
}