/*
 * Copyright (c) 2004 Topspin Communications.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/module.h>
#include <linux/sched/signal.h>

#include <linux/init.h>
#include <linux/seq_file.h>

#include <linux/uaccess.h>

#include "ipoib.h"

static ssize_t parent_show(struct device *d, struct device_attribute *attr,
                           char *buf)
{
        struct net_device *dev = to_net_dev(d);
        struct ipoib_dev_priv *priv = ipoib_priv(dev);

        return sysfs_emit(buf, "%s\n", priv->parent->name);
}
static DEVICE_ATTR_RO(parent);

static bool is_child_unique(struct ipoib_dev_priv *ppriv,
                            struct ipoib_dev_priv *priv)
{
        struct ipoib_dev_priv *tpriv;

        ASSERT_RTNL();

        /*
         * Since the legacy sysfs interface uses pkey for deletion it cannot
         * support more than one interface with the same pkey, it creates
         * ambiguity.  The RTNL interface deletes using the netdev so it does
         * not have a problem to support duplicated pkeys.
         */
        if (priv->child_type != IPOIB_LEGACY_CHILD)
                return true;

        /*
         * First ensure this isn't a duplicate. We check the parent device and
         * then all of the legacy child interfaces to make sure the Pkey
         * doesn't match.
         */
        if (ppriv->pkey == priv->pkey)
                return false;

        list_for_each_entry(tpriv, &ppriv->child_intfs, list) {
                if (tpriv->pkey == priv->pkey &&
                    tpriv->child_type == IPOIB_LEGACY_CHILD)
                        return false;
        }

        return true;
}

/*
 * NOTE: If this function fails then the priv->dev will remain valid, however
 * priv will have been freed and must not be touched by caller in the error
 * case.
 *
 * If (ndev->reg_state == NETREG_UNINITIALIZED) then it is up to the caller to
 * free the net_device (just as rtnl_newlink does) otherwise the net_device
 * will be freed when the rtnl is unlocked.
 */
int __ipoib_vlan_add(struct ipoib_dev_priv *ppriv, struct ipoib_dev_priv *priv,
                     u16 pkey, int type)
{
        struct net_device *ndev = priv->dev;
        int result;
        struct rdma_netdev *rn = netdev_priv(ndev);

        ASSERT_RTNL();

        /*
         * We do not need to touch priv if register_netdevice fails, so just
         * always use this flow.
         */
        ndev->priv_destructor = ipoib_intf_free;

        /*
         * Racing with unregister of the parent must be prevented by the
         * caller.
         */
        WARN_ON(ppriv->dev->reg_state != NETREG_REGISTERED);

        if (pkey == 0 || pkey == 0x8000) {
                result = -EINVAL;
                goto out_early;
        }

        rn->mtu = priv->mcast_mtu;

        priv->parent = ppriv->dev;
        priv->pkey = pkey;
        priv->child_type = type;

        if (!is_child_unique(ppriv, priv)) {
                result = -ENOTUNIQ;
                goto out_early;
        }

        result = register_netdevice(ndev);
        if (result) {
                ipoib_warn(priv, "failed to initialize; error %i", result);

                /*
                 * register_netdevice sometimes calls priv_destructor,
                 * sometimes not. Make sure it was done.
                 */
                goto out_early;
        }

        /* RTNL childs don't need proprietary sysfs entries */
        if (type == IPOIB_LEGACY_CHILD) {
                if (ipoib_cm_add_mode_attr(ndev))
                        goto sysfs_failed;
                if (ipoib_add_pkey_attr(ndev))
                        goto sysfs_failed;
                if (ipoib_add_umcast_attr(ndev))
                        goto sysfs_failed;

                if (device_create_file(&ndev->dev, &dev_attr_parent))
                        goto sysfs_failed;
        }

        return 0;

sysfs_failed:
        unregister_netdevice(priv->dev);
        return -ENOMEM;

out_early:
        if (ndev->priv_destructor)
                ndev->priv_destructor(ndev);
        return result;
}

int ipoib_vlan_add(struct net_device *pdev, unsigned short pkey)
{
        struct ipoib_dev_priv *ppriv, *priv;
        char intf_name[IFNAMSIZ];
        struct net_device *ndev;
        int result;

        if (!capable(CAP_NET_ADMIN))
                return -EPERM;

        if (!rtnl_trylock())
                return restart_syscall();

        if (pdev->reg_state != NETREG_REGISTERED) {
                rtnl_unlock();
                return -EPERM;
        }

        ppriv = ipoib_priv(pdev);

        snprintf(intf_name, sizeof(intf_name), "%s.%04x",
                 ppriv->dev->name, pkey);

        ndev = ipoib_intf_alloc(ppriv->ca, ppriv->port, intf_name);
        if (IS_ERR(ndev)) {
                result = PTR_ERR(ndev);
                goto out;
        }
        priv = ipoib_priv(ndev);

        ndev->rtnl_link_ops = ipoib_get_link_ops();

        result = __ipoib_vlan_add(ppriv, priv, pkey, IPOIB_LEGACY_CHILD);

        if (result && ndev->reg_state == NETREG_UNINITIALIZED)
                free_netdev(ndev);

out:
        rtnl_unlock();

        return result;
}

struct ipoib_vlan_delete_work {
        struct work_struct work;
        struct net_device *dev;
};

/*
 * sysfs callbacks of a netdevice cannot obtain the rtnl lock as
 * unregister_netdev ultimately deletes the sysfs files while holding the rtnl
 * lock. This deadlocks the system.
 *
 * A callback can use rtnl_trylock to avoid the deadlock but it cannot call
 * unregister_netdev as that internally takes and releases the rtnl_lock.  So
 * instead we find the netdev to unregister and then do the actual unregister
 * from the global work queue where we can obtain the rtnl_lock safely.
 */
static void ipoib_vlan_delete_task(struct work_struct *work)
{
        struct ipoib_vlan_delete_work *pwork =
                container_of(work, struct ipoib_vlan_delete_work, work);
        struct net_device *dev = pwork->dev;

        rtnl_lock();

        /* Unregistering tasks can race with another task or parent removal */
        if (dev->reg_state == NETREG_REGISTERED) {
                struct ipoib_dev_priv *priv = ipoib_priv(dev);
                struct ipoib_dev_priv *ppriv = ipoib_priv(priv->parent);

                ipoib_dbg(ppriv, "delete child vlan %s\n", dev->name);
                unregister_netdevice(dev);
        }

        rtnl_unlock();

        kfree(pwork);
}

int ipoib_vlan_delete(struct net_device *pdev, unsigned short pkey)
{
        struct ipoib_dev_priv *ppriv, *priv, *tpriv;
        int rc;

        if (!capable(CAP_NET_ADMIN))
                return -EPERM;

        if (!rtnl_trylock())
                return restart_syscall();

        if (pdev->reg_state != NETREG_REGISTERED) {
                rtnl_unlock();
                return -EPERM;
        }

        ppriv = ipoib_priv(pdev);

        rc = -ENODEV;
        list_for_each_entry_safe(priv, tpriv, &ppriv->child_intfs, list) {
                if (priv->pkey == pkey &&
                    priv->child_type == IPOIB_LEGACY_CHILD) {
                        struct ipoib_vlan_delete_work *work;

                        work = kmalloc(sizeof(*work), GFP_KERNEL);
                        if (!work) {
                                rc = -ENOMEM;
                                goto out;
                        }

                        down_write(&ppriv->vlan_rwsem);
                        list_del_init(&priv->list);
                        up_write(&ppriv->vlan_rwsem);
                        work->dev = priv->dev;
                        INIT_WORK(&work->work, ipoib_vlan_delete_task);
                        queue_work(ipoib_workqueue, &work->work);

                        rc = 0;
                        break;
                }
        }

out:
        rtnl_unlock();

        return rc;
}