/*
 * net/switchdev/switchdev.c - Switch device API
 * Copyright (c) 2014-2015 Jiri Pirko <jiri@resnulli.us>
 * Copyright (c) 2014-2015 Scott Feldman <sfeldma@gmail.com>
 *
 * 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.
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_bridge.h>
#include <linux/list.h>
#include <linux/workqueue.h>
#include <linux/if_vlan.h>
#include <linux/rtnetlink.h>
#include <net/switchdev.h>

/**
 *      switchdev_trans_item_enqueue - Enqueue data item to transaction queue
 *
 *      @trans: transaction
 *      @data: pointer to data being queued
 *      @destructor: data destructor
 *      @tritem: transaction item being queued
 *
 *      Enqeueue data item to transaction queue. tritem is typically placed in
 *      cointainter pointed at by data pointer. Destructor is called on
 *      transaction abort and after successful commit phase in case
 *      the caller did not dequeue the item before.
 */
void switchdev_trans_item_enqueue(struct switchdev_trans *trans,
                                  void *data, void (*destructor)(void const *),
                                  struct switchdev_trans_item *tritem)
{
        tritem->data = data;
        tritem->destructor = destructor;
        list_add_tail(&tritem->list, &trans->item_list);
}
EXPORT_SYMBOL_GPL(switchdev_trans_item_enqueue);

static struct switchdev_trans_item *
__switchdev_trans_item_dequeue(struct switchdev_trans *trans)
{
        struct switchdev_trans_item *tritem;

        if (list_empty(&trans->item_list))
                return NULL;
        tritem = list_first_entry(&trans->item_list,
                                  struct switchdev_trans_item, list);
        list_del(&tritem->list);
        return tritem;
}

/**
 *      switchdev_trans_item_dequeue - Dequeue data item from transaction queue
 *
 *      @trans: transaction
 */
void *switchdev_trans_item_dequeue(struct switchdev_trans *trans)
{
        struct switchdev_trans_item *tritem;

        tritem = __switchdev_trans_item_dequeue(trans);
        BUG_ON(!tritem);
        return tritem->data;
}
EXPORT_SYMBOL_GPL(switchdev_trans_item_dequeue);

static void switchdev_trans_init(struct switchdev_trans *trans)
{
        INIT_LIST_HEAD(&trans->item_list);
}

static void switchdev_trans_items_destroy(struct switchdev_trans *trans)
{
        struct switchdev_trans_item *tritem;

        while ((tritem = __switchdev_trans_item_dequeue(trans)))
                tritem->destructor(tritem->data);
}

static void switchdev_trans_items_warn_destroy(struct net_device *dev,
                                               struct switchdev_trans *trans)
{
        WARN(!list_empty(&trans->item_list), "%s: transaction item queue is not empty.\n",
             dev->name);
        switchdev_trans_items_destroy(trans);
}

static LIST_HEAD(deferred);
static DEFINE_SPINLOCK(deferred_lock);

typedef void switchdev_deferred_func_t(struct net_device *dev,
                                       const void *data);

struct switchdev_deferred_item {
        struct list_head list;
        struct net_device *dev;
        switchdev_deferred_func_t *func;
        unsigned long data[0];
};

static struct switchdev_deferred_item *switchdev_deferred_dequeue(void)
{
        struct switchdev_deferred_item *dfitem;

        spin_lock_bh(&deferred_lock);
        if (list_empty(&deferred)) {
                dfitem = NULL;
                goto unlock;
        }
        dfitem = list_first_entry(&deferred,
                                  struct switchdev_deferred_item, list);
        list_del(&dfitem->list);
unlock:
        spin_unlock_bh(&deferred_lock);
        return dfitem;
}

/**
 *      switchdev_deferred_process - Process ops in deferred queue
 *
 *      Called to flush the ops currently queued in deferred ops queue.
 *      rtnl_lock must be held.
 */
void switchdev_deferred_process(void)
{
        struct switchdev_deferred_item *dfitem;

        ASSERT_RTNL();

        while ((dfitem = switchdev_deferred_dequeue())) {
                dfitem->func(dfitem->dev, dfitem->data);
                dev_put(dfitem->dev);
                kfree(dfitem);
        }
}
EXPORT_SYMBOL_GPL(switchdev_deferred_process);

static void switchdev_deferred_process_work(struct work_struct *work)
{
        rtnl_lock();
        switchdev_deferred_process();
        rtnl_unlock();
}

static DECLARE_WORK(deferred_process_work, switchdev_deferred_process_work);

static int switchdev_deferred_enqueue(struct net_device *dev,
                                      const void *data, size_t data_len,
                                      switchdev_deferred_func_t *func)
{
        struct switchdev_deferred_item *dfitem;

        dfitem = kmalloc(sizeof(*dfitem) + data_len, GFP_ATOMIC);
        if (!dfitem)
                return -ENOMEM;
        dfitem->dev = dev;
        dfitem->func = func;
        memcpy(dfitem->data, data, data_len);
        dev_hold(dev);
        spin_lock_bh(&deferred_lock);
        list_add_tail(&dfitem->list, &deferred);
        spin_unlock_bh(&deferred_lock);
        schedule_work(&deferred_process_work);
        return 0;
}

static int switchdev_port_attr_notify(enum switchdev_notifier_type nt,
                                      struct net_device *dev,
                                      const struct switchdev_attr *attr,
                                      struct switchdev_trans *trans)
{
        int err;
        int rc;

        struct switchdev_notifier_port_attr_info attr_info = {
                .attr = attr,
                .trans = trans,
                .handled = false,
        };

        rc = call_switchdev_blocking_notifiers(nt, dev,
                                               &attr_info.info, NULL);
        err = notifier_to_errno(rc);
        if (err) {
                WARN_ON(!attr_info.handled);
                return err;
        }

        if (!attr_info.handled)
                return -EOPNOTSUPP;

        return 0;
}

static int switchdev_port_attr_set_now(struct net_device *dev,
                                       const struct switchdev_attr *attr)
{
        struct switchdev_trans trans;
        int err;

        switchdev_trans_init(&trans);

        /* Phase I: prepare for attr set. Driver/device should fail
         * here if there are going to be issues in the commit phase,
         * such as lack of resources or support.  The driver/device
         * should reserve resources needed for the commit phase here,
         * but should not commit the attr.
         */

        trans.ph_prepare = true;
        err = switchdev_port_attr_notify(SWITCHDEV_PORT_ATTR_SET, dev, attr,
                                         &trans);
        if (err) {
                /* Prepare phase failed: abort the transaction.  Any
                 * resources reserved in the prepare phase are
                 * released.
                 */

                if (err != -EOPNOTSUPP)
                        switchdev_trans_items_destroy(&trans);

                return err;
        }

        /* Phase II: commit attr set.  This cannot fail as a fault
         * of driver/device.  If it does, it's a bug in the driver/device
         * because the driver said everythings was OK in phase I.
         */

        trans.ph_prepare = false;
        err = switchdev_port_attr_notify(SWITCHDEV_PORT_ATTR_SET, dev, attr,
                                         &trans);
        WARN(err, "%s: Commit of attribute (id=%d) failed.\n",
             dev->name, attr->id);
        switchdev_trans_items_warn_destroy(dev, &trans);

        return err;
}

static void switchdev_port_attr_set_deferred(struct net_device *dev,
                                             const void *data)
{
        const struct switchdev_attr *attr = data;
        int err;

        err = switchdev_port_attr_set_now(dev, attr);
        if (err && err != -EOPNOTSUPP)
                netdev_err(dev, "failed (err=%d) to set attribute (id=%d)\n",
                           err, attr->id);
        if (attr->complete)
                attr->complete(dev, err, attr->complete_priv);
}

static int switchdev_port_attr_set_defer(struct net_device *dev,
                                         const struct switchdev_attr *attr)
{
        return switchdev_deferred_enqueue(dev, attr, sizeof(*attr),
                                          switchdev_port_attr_set_deferred);
}

/**
 *      switchdev_port_attr_set - Set port attribute
 *
 *      @dev: port device
 *      @attr: attribute to set
 *
 *      Use a 2-phase prepare-commit transaction model to ensure
 *      system is not left in a partially updated state due to
 *      failure from driver/device.
 *
 *      rtnl_lock must be held and must not be in atomic section,
 *      in case SWITCHDEV_F_DEFER flag is not set.
 */
int switchdev_port_attr_set(struct net_device *dev,
                            const struct switchdev_attr *attr)
{
        if (attr->flags & SWITCHDEV_F_DEFER)
                return switchdev_port_attr_set_defer(dev, attr);
        ASSERT_RTNL();
        return switchdev_port_attr_set_now(dev, attr);
}
EXPORT_SYMBOL_GPL(switchdev_port_attr_set);

static size_t switchdev_obj_size(const struct switchdev_obj *obj)
{
        switch (obj->id) {
        case SWITCHDEV_OBJ_ID_PORT_VLAN:
                return sizeof(struct switchdev_obj_port_vlan);
        case SWITCHDEV_OBJ_ID_PORT_MDB:
                return sizeof(struct switchdev_obj_port_mdb);
        case SWITCHDEV_OBJ_ID_HOST_MDB:
                return sizeof(struct switchdev_obj_port_mdb);
        default:
                BUG();
        }
        return 0;
}

static int switchdev_port_obj_notify(enum switchdev_notifier_type nt,
                                     struct net_device *dev,
                                     const struct switchdev_obj *obj,
                                     struct switchdev_trans *trans,
                                     struct netlink_ext_ack *extack)
{
        int rc;
        int err;

        struct switchdev_notifier_port_obj_info obj_info = {
                .obj = obj,
                .trans = trans,
                .handled = false,
        };

        rc = call_switchdev_blocking_notifiers(nt, dev, &obj_info.info, extack);
        err = notifier_to_errno(rc);
        if (err) {
                WARN_ON(!obj_info.handled);
                return err;
        }
        if (!obj_info.handled)
                return -EOPNOTSUPP;
        return 0;
}

static int switchdev_port_obj_add_now(struct net_device *dev,
                                      const struct switchdev_obj *obj,
                                      struct netlink_ext_ack *extack)
{
        struct switchdev_trans trans;
        int err;

        ASSERT_RTNL();

        switchdev_trans_init(&trans);

        /* Phase I: prepare for obj add. Driver/device should fail
         * here if there are going to be issues in the commit phase,
         * such as lack of resources or support.  The driver/device
         * should reserve resources needed for the commit phase here,
         * but should not commit the obj.
         */

        trans.ph_prepare = true;
        err = switchdev_port_obj_notify(SWITCHDEV_PORT_OBJ_ADD,
                                        dev, obj, &trans, extack);
        if (err) {
                /* Prepare phase failed: abort the transaction.  Any
                 * resources reserved in the prepare phase are
                 * released.
                 */

                if (err != -EOPNOTSUPP)
                        switchdev_trans_items_destroy(&trans);

                return err;
        }

        /* Phase II: commit obj add.  This cannot fail as a fault
         * of driver/device.  If it does, it's a bug in the driver/device
         * because the driver said everythings was OK in phase I.
         */

        trans.ph_prepare = false;
        err = switchdev_port_obj_notify(SWITCHDEV_PORT_OBJ_ADD,
                                        dev, obj, &trans, extack);
        WARN(err, "%s: Commit of object (id=%d) failed.\n", dev->name, obj->id);
        switchdev_trans_items_warn_destroy(dev, &trans);

        return err;
}

static void switchdev_port_obj_add_deferred(struct net_device *dev,
                                            const void *data)
{
        const struct switchdev_obj *obj = data;
        int err;

        err = switchdev_port_obj_add_now(dev, obj, NULL);
        if (err && err != -EOPNOTSUPP)
                netdev_err(dev, "failed (err=%d) to add object (id=%d)\n",
                           err, obj->id);
        if (obj->complete)
                obj->complete(dev, err, obj->complete_priv);
}

static int switchdev_port_obj_add_defer(struct net_device *dev,
                                        const struct switchdev_obj *obj)
{
        return switchdev_deferred_enqueue(dev, obj, switchdev_obj_size(obj),
                                          switchdev_port_obj_add_deferred);
}

/**
 *      switchdev_port_obj_add - Add port object
 *
 *      @dev: port device
 *      @id: object ID
 *      @obj: object to add
 *
 *      Use a 2-phase prepare-commit transaction model to ensure
 *      system is not left in a partially updated state due to
 *      failure from driver/device.
 *
 *      rtnl_lock must be held and must not be in atomic section,
 *      in case SWITCHDEV_F_DEFER flag is not set.
 */
int switchdev_port_obj_add(struct net_device *dev,
                           const struct switchdev_obj *obj,
                           struct netlink_ext_ack *extack)
{
        if (obj->flags & SWITCHDEV_F_DEFER)
                return switchdev_port_obj_add_defer(dev, obj);
        ASSERT_RTNL();
        return switchdev_port_obj_add_now(dev, obj, extack);
}
EXPORT_SYMBOL_GPL(switchdev_port_obj_add);

static int switchdev_port_obj_del_now(struct net_device *dev,
                                      const struct switchdev_obj *obj)
{
        return switchdev_port_obj_notify(SWITCHDEV_PORT_OBJ_DEL,
                                         dev, obj, NULL, NULL);
}

static void switchdev_port_obj_del_deferred(struct net_device *dev,
                                            const void *data)
{
        const struct switchdev_obj *obj = data;
        int err;

        err = switchdev_port_obj_del_now(dev, obj);
        if (err && err != -EOPNOTSUPP)
                netdev_err(dev, "failed (err=%d) to del object (id=%d)\n",
                           err, obj->id);
        if (obj->complete)
                obj->complete(dev, err, obj->complete_priv);
}

static int switchdev_port_obj_del_defer(struct net_device *dev,
                                        const struct switchdev_obj *obj)
{
        return switchdev_deferred_enqueue(dev, obj, switchdev_obj_size(obj),
                                          switchdev_port_obj_del_deferred);
}

/**
 *      switchdev_port_obj_del - Delete port object
 *
 *      @dev: port device
 *      @id: object ID
 *      @obj: object to delete
 *
 *      rtnl_lock must be held and must not be in atomic section,
 *      in case SWITCHDEV_F_DEFER flag is not set.
 */
int switchdev_port_obj_del(struct net_device *dev,
                           const struct switchdev_obj *obj)
{
        if (obj->flags & SWITCHDEV_F_DEFER)
                return switchdev_port_obj_del_defer(dev, obj);
        ASSERT_RTNL();
        return switchdev_port_obj_del_now(dev, obj);
}
EXPORT_SYMBOL_GPL(switchdev_port_obj_del);

static ATOMIC_NOTIFIER_HEAD(switchdev_notif_chain);
static BLOCKING_NOTIFIER_HEAD(switchdev_blocking_notif_chain);

/**
 *      register_switchdev_notifier - Register notifier
 *      @nb: notifier_block
 *
 *      Register switch device notifier.
 */
int register_switchdev_notifier(struct notifier_block *nb)
{
        return atomic_notifier_chain_register(&switchdev_notif_chain, nb);
}
EXPORT_SYMBOL_GPL(register_switchdev_notifier);

/**
 *      unregister_switchdev_notifier - Unregister notifier
 *      @nb: notifier_block
 *
 *      Unregister switch device notifier.
 */
int unregister_switchdev_notifier(struct notifier_block *nb)
{
        return atomic_notifier_chain_unregister(&switchdev_notif_chain, nb);
}
EXPORT_SYMBOL_GPL(unregister_switchdev_notifier);

/**
 *      call_switchdev_notifiers - Call notifiers
 *      @val: value passed unmodified to notifier function
 *      @dev: port device
 *      @info: notifier information data
 *
 *      Call all network notifier blocks.
 */
int call_switchdev_notifiers(unsigned long val, struct net_device *dev,
                             struct switchdev_notifier_info *info,
                             struct netlink_ext_ack *extack)
{
        info->dev = dev;
        info->extack = extack;
        return atomic_notifier_call_chain(&switchdev_notif_chain, val, info);
}
EXPORT_SYMBOL_GPL(call_switchdev_notifiers);

int register_switchdev_blocking_notifier(struct notifier_block *nb)
{
        struct blocking_notifier_head *chain = &switchdev_blocking_notif_chain;

        return blocking_notifier_chain_register(chain, nb);
}
EXPORT_SYMBOL_GPL(register_switchdev_blocking_notifier);

int unregister_switchdev_blocking_notifier(struct notifier_block *nb)
{
        struct blocking_notifier_head *chain = &switchdev_blocking_notif_chain;

        return blocking_notifier_chain_unregister(chain, nb);
}
EXPORT_SYMBOL_GPL(unregister_switchdev_blocking_notifier);

int call_switchdev_blocking_notifiers(unsigned long val, struct net_device *dev,
                                      struct switchdev_notifier_info *info,
                                      struct netlink_ext_ack *extack)
{
        info->dev = dev;
        info->extack = extack;
        return blocking_notifier_call_chain(&switchdev_blocking_notif_chain,
                                            val, info);
}
EXPORT_SYMBOL_GPL(call_switchdev_blocking_notifiers);

static int __switchdev_handle_port_obj_add(struct net_device *dev,
                        struct switchdev_notifier_port_obj_info *port_obj_info,
                        bool (*check_cb)(const struct net_device *dev),
                        int (*add_cb)(struct net_device *dev,
                                      const struct switchdev_obj *obj,
                                      struct switchdev_trans *trans,
                                      struct netlink_ext_ack *extack))
{
        struct netlink_ext_ack *extack;
        struct net_device *lower_dev;
        struct list_head *iter;
        int err = -EOPNOTSUPP;

        extack = switchdev_notifier_info_to_extack(&port_obj_info->info);

        if (check_cb(dev)) {
                /* This flag is only checked if the return value is success. */
                port_obj_info->handled = true;
                return add_cb(dev, port_obj_info->obj, port_obj_info->trans,
                              extack);
        }

        /* Switch ports might be stacked under e.g. a LAG. Ignore the
         * unsupported devices, another driver might be able to handle them. But
         * propagate to the callers any hard errors.
         *
         * If the driver does its own bookkeeping of stacked ports, it's not
         * necessary to go through this helper.
         */
        netdev_for_each_lower_dev(dev, lower_dev, iter) {
                err = __switchdev_handle_port_obj_add(lower_dev, port_obj_info,
                                                      check_cb, add_cb);
                if (err && err != -EOPNOTSUPP)
                        return err;
        }

        return err;
}

int switchdev_handle_port_obj_add(struct net_device *dev,
                        struct switchdev_notifier_port_obj_info *port_obj_info,
                        bool (*check_cb)(const struct net_device *dev),
                        int (*add_cb)(struct net_device *dev,
                                      const struct switchdev_obj *obj,
                                      struct switchdev_trans *trans,
                                      struct netlink_ext_ack *extack))
{
        int err;

        err = __switchdev_handle_port_obj_add(dev, port_obj_info, check_cb,
                                              add_cb);
        if (err == -EOPNOTSUPP)
                err = 0;
        return err;
}
EXPORT_SYMBOL_GPL(switchdev_handle_port_obj_add);

static int __switchdev_handle_port_obj_del(struct net_device *dev,
                        struct switchdev_notifier_port_obj_info *port_obj_info,
                        bool (*check_cb)(const struct net_device *dev),
                        int (*del_cb)(struct net_device *dev,
                                      const struct switchdev_obj *obj))
{
        struct net_device *lower_dev;
        struct list_head *iter;
        int err = -EOPNOTSUPP;

        if (check_cb(dev)) {
                /* This flag is only checked if the return value is success. */
                port_obj_info->handled = true;
                return del_cb(dev, port_obj_info->obj);
        }

        /* Switch ports might be stacked under e.g. a LAG. Ignore the
         * unsupported devices, another driver might be able to handle them. But
         * propagate to the callers any hard errors.
         *
         * If the driver does its own bookkeeping of stacked ports, it's not
         * necessary to go through this helper.
         */
        netdev_for_each_lower_dev(dev, lower_dev, iter) {
                err = __switchdev_handle_port_obj_del(lower_dev, port_obj_info,
                                                      check_cb, del_cb);
                if (err && err != -EOPNOTSUPP)
                        return err;
        }

        return err;
}

int switchdev_handle_port_obj_del(struct net_device *dev,
                        struct switchdev_notifier_port_obj_info *port_obj_info,
                        bool (*check_cb)(const struct net_device *dev),
                        int (*del_cb)(struct net_device *dev,
                                      const struct switchdev_obj *obj))
{
        int err;

        err = __switchdev_handle_port_obj_del(dev, port_obj_info, check_cb,
                                              del_cb);
        if (err == -EOPNOTSUPP)
                err = 0;
        return err;
}
EXPORT_SYMBOL_GPL(switchdev_handle_port_obj_del);

static int __switchdev_handle_port_attr_set(struct net_device *dev,
                        struct switchdev_notifier_port_attr_info *port_attr_info,
                        bool (*check_cb)(const struct net_device *dev),
                        int (*set_cb)(struct net_device *dev,
                                      const struct switchdev_attr *attr,
                                      struct switchdev_trans *trans))
{
        struct net_device *lower_dev;
        struct list_head *iter;
        int err = -EOPNOTSUPP;

        if (check_cb(dev)) {
                port_attr_info->handled = true;
                return set_cb(dev, port_attr_info->attr,
                              port_attr_info->trans);
        }

        /* Switch ports might be stacked under e.g. a LAG. Ignore the
         * unsupported devices, another driver might be able to handle them. But
         * propagate to the callers any hard errors.
         *
         * If the driver does its own bookkeeping of stacked ports, it's not
         * necessary to go through this helper.
         */
        netdev_for_each_lower_dev(dev, lower_dev, iter) {
                err = __switchdev_handle_port_attr_set(lower_dev, port_attr_info,
                                                       check_cb, set_cb);
                if (err && err != -EOPNOTSUPP)
                        return err;
        }

        return err;
}

int switchdev_handle_port_attr_set(struct net_device *dev,
                        struct switchdev_notifier_port_attr_info *port_attr_info,
                        bool (*check_cb)(const struct net_device *dev),
                        int (*set_cb)(struct net_device *dev,
                                      const struct switchdev_attr *attr,
                                      struct switchdev_trans *trans))
{
        int err;

        err = __switchdev_handle_port_attr_set(dev, port_attr_info, check_cb,
                                               set_cb);
        if (err == -EOPNOTSUPP)
                err = 0;
        return err;
}
EXPORT_SYMBOL_GPL(switchdev_handle_port_attr_set);