mm: vmscan: distinguish between memcg triggering reclaim and memcg being scanned

[linux-2.6.git] / net / tipc / bearer.c

/*
 * net/tipc/bearer.c: TIPC bearer code
 *
 * Copyright (c) 1996-2006, Ericsson AB
 * Copyright (c) 2004-2006, 2010-2011, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "core.h"
#include "config.h"
#include "bearer.h"
#include "discover.h"

#define MAX_ADDR_STR 32

static struct tipc_media *media_list[MAX_MEDIA];
static u32 media_count;

struct tipc_bearer tipc_bearers[MAX_BEARERS];

static void bearer_disable(struct tipc_bearer *b_ptr);

/**
 * media_name_valid - validate media name
 *
 * Returns 1 if media name is valid, otherwise 0.
 */

static int media_name_valid(const char *name)
{
        u32 len;

        len = strlen(name);
        if ((len + 1) > TIPC_MAX_MEDIA_NAME)
                return 0;
        return strspn(name, tipc_alphabet) == len;
}

/**
 * tipc_media_find - locates specified media object by name
 */

struct tipc_media *tipc_media_find(const char *name)
{
        u32 i;

        for (i = 0; i < media_count; i++) {
                if (!strcmp(media_list[i]->name, name))
                        return media_list[i];
        }
        return NULL;
}

/**
 * media_find_id - locates specified media object by type identifier
 */

static struct tipc_media *media_find_id(u8 type)
{
        u32 i;

        for (i = 0; i < media_count; i++) {
                if (media_list[i]->type_id == type)
                        return media_list[i];
        }
        return NULL;
}

/**
 * tipc_register_media - register a media type
 *
 * Bearers for this media type must be activated separately at a later stage.
 */

int tipc_register_media(struct tipc_media *m_ptr)
{
        int res = -EINVAL;

        write_lock_bh(&tipc_net_lock);

        if (!media_name_valid(m_ptr->name))
                goto exit;
        if ((m_ptr->bcast_addr.media_id != m_ptr->type_id) ||
            !m_ptr->bcast_addr.broadcast)
                goto exit;
        if (m_ptr->priority > TIPC_MAX_LINK_PRI)
                goto exit;
        if ((m_ptr->tolerance < TIPC_MIN_LINK_TOL) ||
            (m_ptr->tolerance > TIPC_MAX_LINK_TOL))
                goto exit;
        if (media_count >= MAX_MEDIA)
                goto exit;
        if (tipc_media_find(m_ptr->name) || media_find_id(m_ptr->type_id))
                goto exit;

        media_list[media_count] = m_ptr;
        media_count++;
        res = 0;
exit:
        write_unlock_bh(&tipc_net_lock);
        if (res)
                warn("Media <%s> registration error\n", m_ptr->name);
        return res;
}

/**
 * tipc_media_addr_printf - record media address in print buffer
 */

void tipc_media_addr_printf(struct print_buf *pb, struct tipc_media_addr *a)
{
        char addr_str[MAX_ADDR_STR];
        struct tipc_media *m_ptr;

        m_ptr = media_find_id(a->media_id);

        if (m_ptr && !m_ptr->addr2str(a, addr_str, sizeof(addr_str)))
                tipc_printf(pb, "%s(%s)", m_ptr->name, addr_str);
        else {
                u32 i;

                tipc_printf(pb, "UNKNOWN(%u)", a->media_id);
                for (i = 0; i < sizeof(a->value); i++)
                        tipc_printf(pb, "-%02x", a->value[i]);
        }
}

/**
 * tipc_media_get_names - record names of registered media in buffer
 */

struct sk_buff *tipc_media_get_names(void)
{
        struct sk_buff *buf;
        int i;

        buf = tipc_cfg_reply_alloc(MAX_MEDIA * TLV_SPACE(TIPC_MAX_MEDIA_NAME));
        if (!buf)
                return NULL;

        read_lock_bh(&tipc_net_lock);
        for (i = 0; i < media_count; i++) {
                tipc_cfg_append_tlv(buf, TIPC_TLV_MEDIA_NAME,
                                    media_list[i]->name,
                                    strlen(media_list[i]->name) + 1);
        }
        read_unlock_bh(&tipc_net_lock);
        return buf;
}

/**
 * bearer_name_validate - validate & (optionally) deconstruct bearer name
 * @name - ptr to bearer name string
 * @name_parts - ptr to area for bearer name components (or NULL if not needed)
 *
 * Returns 1 if bearer name is valid, otherwise 0.
 */

static int bearer_name_validate(const char *name,
                                struct tipc_bearer_names *name_parts)
{
        char name_copy[TIPC_MAX_BEARER_NAME];
        char *media_name;
        char *if_name;
        u32 media_len;
        u32 if_len;

        /* copy bearer name & ensure length is OK */

        name_copy[TIPC_MAX_BEARER_NAME - 1] = 0;
        /* need above in case non-Posix strncpy() doesn't pad with nulls */
        strncpy(name_copy, name, TIPC_MAX_BEARER_NAME);
        if (name_copy[TIPC_MAX_BEARER_NAME - 1] != 0)
                return 0;

        /* ensure all component parts of bearer name are present */

        media_name = name_copy;
        if_name = strchr(media_name, ':');
        if (if_name == NULL)
                return 0;
        *(if_name++) = 0;
        media_len = if_name - media_name;
        if_len = strlen(if_name) + 1;

        /* validate component parts of bearer name */

        if ((media_len <= 1) || (media_len > TIPC_MAX_MEDIA_NAME) ||
            (if_len <= 1) || (if_len > TIPC_MAX_IF_NAME) ||
            (strspn(media_name, tipc_alphabet) != (media_len - 1)) ||
            (strspn(if_name, tipc_alphabet) != (if_len - 1)))
                return 0;

        /* return bearer name components, if necessary */

        if (name_parts) {
                strcpy(name_parts->media_name, media_name);
                strcpy(name_parts->if_name, if_name);
        }
        return 1;
}

/**
 * tipc_bearer_find - locates bearer object with matching bearer name
 */

struct tipc_bearer *tipc_bearer_find(const char *name)
{
        struct tipc_bearer *b_ptr;
        u32 i;

        for (i = 0, b_ptr = tipc_bearers; i < MAX_BEARERS; i++, b_ptr++) {
                if (b_ptr->active && (!strcmp(b_ptr->name, name)))
                        return b_ptr;
        }
        return NULL;
}

/**
 * tipc_bearer_find_interface - locates bearer object with matching interface name
 */

struct tipc_bearer *tipc_bearer_find_interface(const char *if_name)
{
        struct tipc_bearer *b_ptr;
        char *b_if_name;
        u32 i;

        for (i = 0, b_ptr = tipc_bearers; i < MAX_BEARERS; i++, b_ptr++) {
                if (!b_ptr->active)
                        continue;
                b_if_name = strchr(b_ptr->name, ':') + 1;
                if (!strcmp(b_if_name, if_name))
                        return b_ptr;
        }
        return NULL;
}

/**
 * tipc_bearer_get_names - record names of bearers in buffer
 */

struct sk_buff *tipc_bearer_get_names(void)
{
        struct sk_buff *buf;
        struct tipc_bearer *b_ptr;
        int i, j;

        buf = tipc_cfg_reply_alloc(MAX_BEARERS * TLV_SPACE(TIPC_MAX_BEARER_NAME));
        if (!buf)
                return NULL;

        read_lock_bh(&tipc_net_lock);
        for (i = 0; i < media_count; i++) {
                for (j = 0; j < MAX_BEARERS; j++) {
                        b_ptr = &tipc_bearers[j];
                        if (b_ptr->active && (b_ptr->media == media_list[i])) {
                                tipc_cfg_append_tlv(buf, TIPC_TLV_BEARER_NAME,
                                                    b_ptr->name,
                                                    strlen(b_ptr->name) + 1);
                        }
                }
        }
        read_unlock_bh(&tipc_net_lock);
        return buf;
}

void tipc_bearer_add_dest(struct tipc_bearer *b_ptr, u32 dest)
{
        tipc_nmap_add(&b_ptr->nodes, dest);
        tipc_bcbearer_sort();
        tipc_disc_add_dest(b_ptr->link_req);
}

void tipc_bearer_remove_dest(struct tipc_bearer *b_ptr, u32 dest)
{
        tipc_nmap_remove(&b_ptr->nodes, dest);
        tipc_bcbearer_sort();
        tipc_disc_remove_dest(b_ptr->link_req);
}

/*
 * bearer_push(): Resolve bearer congestion. Force the waiting
 * links to push out their unsent packets, one packet per link
 * per iteration, until all packets are gone or congestion reoccurs.
 * 'tipc_net_lock' is read_locked when this function is called
 * bearer.lock must be taken before calling
 * Returns binary true(1) ore false(0)
 */
static int bearer_push(struct tipc_bearer *b_ptr)
{
        u32 res = 0;
        struct tipc_link *ln, *tln;

        if (b_ptr->blocked)
                return 0;

        while (!list_empty(&b_ptr->cong_links) && (res != PUSH_FAILED)) {
                list_for_each_entry_safe(ln, tln, &b_ptr->cong_links, link_list) {
                        res = tipc_link_push_packet(ln);
                        if (res == PUSH_FAILED)
                                break;
                        if (res == PUSH_FINISHED)
                                list_move_tail(&ln->link_list, &b_ptr->links);
                }
        }
        return list_empty(&b_ptr->cong_links);
}

void tipc_bearer_lock_push(struct tipc_bearer *b_ptr)
{
        spin_lock_bh(&b_ptr->lock);
        bearer_push(b_ptr);
        spin_unlock_bh(&b_ptr->lock);
}


/*
 * Interrupt enabling new requests after bearer congestion or blocking:
 * See bearer_send().
 */
void tipc_continue(struct tipc_bearer *b_ptr)
{
        spin_lock_bh(&b_ptr->lock);
        if (!list_empty(&b_ptr->cong_links))
                tipc_k_signal((Handler)tipc_bearer_lock_push, (unsigned long)b_ptr);
        b_ptr->blocked = 0;
        spin_unlock_bh(&b_ptr->lock);
}

/*
 * Schedule link for sending of messages after the bearer
 * has been deblocked by 'continue()'. This method is called
 * when somebody tries to send a message via this link while
 * the bearer is congested. 'tipc_net_lock' is in read_lock here
 * bearer.lock is busy
 */

static void tipc_bearer_schedule_unlocked(struct tipc_bearer *b_ptr,
                                                struct tipc_link *l_ptr)
{
        list_move_tail(&l_ptr->link_list, &b_ptr->cong_links);
}

/*
 * Schedule link for sending of messages after the bearer
 * has been deblocked by 'continue()'. This method is called
 * when somebody tries to send a message via this link while
 * the bearer is congested. 'tipc_net_lock' is in read_lock here,
 * bearer.lock is free
 */

void tipc_bearer_schedule(struct tipc_bearer *b_ptr, struct tipc_link *l_ptr)
{
        spin_lock_bh(&b_ptr->lock);
        tipc_bearer_schedule_unlocked(b_ptr, l_ptr);
        spin_unlock_bh(&b_ptr->lock);
}


/*
 * tipc_bearer_resolve_congestion(): Check if there is bearer congestion,
 * and if there is, try to resolve it before returning.
 * 'tipc_net_lock' is read_locked when this function is called
 */
int tipc_bearer_resolve_congestion(struct tipc_bearer *b_ptr,
                                        struct tipc_link *l_ptr)
{
        int res = 1;

        if (list_empty(&b_ptr->cong_links))
                return 1;
        spin_lock_bh(&b_ptr->lock);
        if (!bearer_push(b_ptr)) {
                tipc_bearer_schedule_unlocked(b_ptr, l_ptr);
                res = 0;
        }
        spin_unlock_bh(&b_ptr->lock);
        return res;
}

/**
 * tipc_bearer_congested - determines if bearer is currently congested
 */

int tipc_bearer_congested(struct tipc_bearer *b_ptr, struct tipc_link *l_ptr)
{
        if (unlikely(b_ptr->blocked))
                return 1;
        if (likely(list_empty(&b_ptr->cong_links)))
                return 0;
        return !tipc_bearer_resolve_congestion(b_ptr, l_ptr);
}

/**
 * tipc_enable_bearer - enable bearer with the given name
 */

int tipc_enable_bearer(const char *name, u32 disc_domain, u32 priority)
{
        struct tipc_bearer *b_ptr;
        struct tipc_media *m_ptr;
        struct tipc_bearer_names b_names;
        char addr_string[16];
        u32 bearer_id;
        u32 with_this_prio;
        u32 i;
        int res = -EINVAL;

        if (tipc_mode != TIPC_NET_MODE) {
                warn("Bearer <%s> rejected, not supported in standalone mode\n",
                     name);
                return -ENOPROTOOPT;
        }
        if (!bearer_name_validate(name, &b_names)) {
                warn("Bearer <%s> rejected, illegal name\n", name);
                return -EINVAL;
        }
        if (tipc_addr_domain_valid(disc_domain) &&
            (disc_domain != tipc_own_addr)) {
                if (tipc_in_scope(disc_domain, tipc_own_addr)) {
                        disc_domain = tipc_own_addr & TIPC_CLUSTER_MASK;
                        res = 0;   /* accept any node in own cluster */
                } else if (in_own_cluster(disc_domain))
                        res = 0;   /* accept specified node in own cluster */
        }
        if (res) {
                warn("Bearer <%s> rejected, illegal discovery domain\n", name);
                return -EINVAL;
        }
        if ((priority < TIPC_MIN_LINK_PRI ||
             priority > TIPC_MAX_LINK_PRI) &&
            (priority != TIPC_MEDIA_LINK_PRI)) {
                warn("Bearer <%s> rejected, illegal priority\n", name);
                return -EINVAL;
        }

        write_lock_bh(&tipc_net_lock);

        m_ptr = tipc_media_find(b_names.media_name);
        if (!m_ptr) {
                warn("Bearer <%s> rejected, media <%s> not registered\n", name,
                     b_names.media_name);
                goto exit;
        }

        if (priority == TIPC_MEDIA_LINK_PRI)
                priority = m_ptr->priority;

restart:
        bearer_id = MAX_BEARERS;
        with_this_prio = 1;
        for (i = MAX_BEARERS; i-- != 0; ) {
                if (!tipc_bearers[i].active) {
                        bearer_id = i;
                        continue;
                }
                if (!strcmp(name, tipc_bearers[i].name)) {
                        warn("Bearer <%s> rejected, already enabled\n", name);
                        goto exit;
                }
                if ((tipc_bearers[i].priority == priority) &&
                    (++with_this_prio > 2)) {
                        if (priority-- == 0) {
                                warn("Bearer <%s> rejected, duplicate priority\n",
                                     name);
                                goto exit;
                        }
                        warn("Bearer <%s> priority adjustment required %u->%u\n",
                             name, priority + 1, priority);
                        goto restart;
                }
        }
        if (bearer_id >= MAX_BEARERS) {
                warn("Bearer <%s> rejected, bearer limit reached (%u)\n",
                     name, MAX_BEARERS);
                goto exit;
        }

        b_ptr = &tipc_bearers[bearer_id];
        strcpy(b_ptr->name, name);
        res = m_ptr->enable_bearer(b_ptr);
        if (res) {
                warn("Bearer <%s> rejected, enable failure (%d)\n", name, -res);
                goto exit;
        }

        b_ptr->identity = bearer_id;
        b_ptr->media = m_ptr;
        b_ptr->tolerance = m_ptr->tolerance;
        b_ptr->window = m_ptr->window;
        b_ptr->net_plane = bearer_id + 'A';
        b_ptr->active = 1;
        b_ptr->priority = priority;
        INIT_LIST_HEAD(&b_ptr->cong_links);
        INIT_LIST_HEAD(&b_ptr->links);
        spin_lock_init(&b_ptr->lock);

        res = tipc_disc_create(b_ptr, &m_ptr->bcast_addr, disc_domain);
        if (res) {
                bearer_disable(b_ptr);
                warn("Bearer <%s> rejected, discovery object creation failed\n",
                     name);
                goto exit;
        }
        info("Enabled bearer <%s>, discovery domain %s, priority %u\n",
             name, tipc_addr_string_fill(addr_string, disc_domain), priority);
exit:
        write_unlock_bh(&tipc_net_lock);
        return res;
}

/**
 * tipc_block_bearer(): Block the bearer with the given name,
 *                      and reset all its links
 */

int tipc_block_bearer(const char *name)
{
        struct tipc_bearer *b_ptr = NULL;
        struct tipc_link *l_ptr;
        struct tipc_link *temp_l_ptr;

        read_lock_bh(&tipc_net_lock);
        b_ptr = tipc_bearer_find(name);
        if (!b_ptr) {
                warn("Attempt to block unknown bearer <%s>\n", name);
                read_unlock_bh(&tipc_net_lock);
                return -EINVAL;
        }

        info("Blocking bearer <%s>\n", name);
        spin_lock_bh(&b_ptr->lock);
        b_ptr->blocked = 1;
        list_splice_init(&b_ptr->cong_links, &b_ptr->links);
        list_for_each_entry_safe(l_ptr, temp_l_ptr, &b_ptr->links, link_list) {
                struct tipc_node *n_ptr = l_ptr->owner;

                spin_lock_bh(&n_ptr->lock);
                tipc_link_reset(l_ptr);
                spin_unlock_bh(&n_ptr->lock);
        }
        spin_unlock_bh(&b_ptr->lock);
        read_unlock_bh(&tipc_net_lock);
        return 0;
}

/**
 * bearer_disable -
 *
 * Note: This routine assumes caller holds tipc_net_lock.
 */

static void bearer_disable(struct tipc_bearer *b_ptr)
{
        struct tipc_link *l_ptr;
        struct tipc_link *temp_l_ptr;

        info("Disabling bearer <%s>\n", b_ptr->name);
        spin_lock_bh(&b_ptr->lock);
        b_ptr->blocked = 1;
        b_ptr->media->disable_bearer(b_ptr);
        list_splice_init(&b_ptr->cong_links, &b_ptr->links);
        list_for_each_entry_safe(l_ptr, temp_l_ptr, &b_ptr->links, link_list) {
                tipc_link_delete(l_ptr);
        }
        if (b_ptr->link_req)
                tipc_disc_delete(b_ptr->link_req);
        spin_unlock_bh(&b_ptr->lock);
        memset(b_ptr, 0, sizeof(struct tipc_bearer));
}

int tipc_disable_bearer(const char *name)
{
        struct tipc_bearer *b_ptr;
        int res;

        write_lock_bh(&tipc_net_lock);
        b_ptr = tipc_bearer_find(name);
        if (b_ptr == NULL) {
                warn("Attempt to disable unknown bearer <%s>\n", name);
                res = -EINVAL;
        } else {
                bearer_disable(b_ptr);
                res = 0;
        }
        write_unlock_bh(&tipc_net_lock);
        return res;
}



void tipc_bearer_stop(void)
{
        u32 i;

        for (i = 0; i < MAX_BEARERS; i++) {
                if (tipc_bearers[i].active)
                        bearer_disable(&tipc_bearers[i]);
        }
        media_count = 0;
}