// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2003-2008 Takahiro Hirofuchi
 */

#include <linux/device.h>
#include <linux/file.h>
#include <linux/kthread.h>
#include <linux/module.h>

#include "usbip_common.h"
#include "stub.h"

/*
 * usbip_status shows the status of usbip-host as long as this driver is bound
 * to the target device.
 */
static ssize_t usbip_status_show(struct device *dev,
                                 struct device_attribute *attr, char *buf)
{
        struct stub_device *sdev = dev_get_drvdata(dev);
        int status;

        if (!sdev) {
                dev_err(dev, "sdev is null\n");
                return -ENODEV;
        }

        spin_lock_irq(&sdev->ud.lock);
        status = sdev->ud.status;
        spin_unlock_irq(&sdev->ud.lock);

        return sysfs_emit(buf, "%d\n", status);
}
static DEVICE_ATTR_RO(usbip_status);

/*
 * usbip_sockfd gets a socket descriptor of an established TCP connection that
 * is used to transfer usbip requests by kernel threads. -1 is a magic number
 * by which usbip connection is finished.
 */
static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *attr,
                            const char *buf, size_t count)
{
        struct stub_device *sdev = dev_get_drvdata(dev);
        int sockfd = 0;
        struct socket *socket;
        int rv;
        struct task_struct *tcp_rx = NULL;
        struct task_struct *tcp_tx = NULL;

        if (!sdev) {
                dev_err(dev, "sdev is null\n");
                return -ENODEV;
        }

        rv = sscanf(buf, "%d", &sockfd);
        if (rv != 1)
                return -EINVAL;

        if (sockfd != -1) {
                int err;

                dev_info(dev, "stub up\n");

                mutex_lock(&sdev->ud.sysfs_lock);
                spin_lock_irq(&sdev->ud.lock);

                if (sdev->ud.status != SDEV_ST_AVAILABLE) {
                        dev_err(dev, "not ready\n");
                        goto err;
                }

                socket = sockfd_lookup(sockfd, &err);
                if (!socket) {
                        dev_err(dev, "failed to lookup sock");
                        goto err;
                }

                if (socket->type != SOCK_STREAM) {
                        dev_err(dev, "Expecting SOCK_STREAM - found %d",
                                socket->type);
                        goto sock_err;
                }

                /* unlock and create threads and get tasks */
                spin_unlock_irq(&sdev->ud.lock);
                tcp_rx = kthread_create(stub_rx_loop, &sdev->ud, "stub_rx");
                if (IS_ERR(tcp_rx)) {
                        sockfd_put(socket);
                        goto unlock_mutex;
                }
                tcp_tx = kthread_create(stub_tx_loop, &sdev->ud, "stub_tx");
                if (IS_ERR(tcp_tx)) {
                        kthread_stop(tcp_rx);
                        sockfd_put(socket);
                        goto unlock_mutex;
                }

                /* get task structs now */
                get_task_struct(tcp_rx);
                get_task_struct(tcp_tx);

                /* lock and update sdev->ud state */
                spin_lock_irq(&sdev->ud.lock);
                sdev->ud.tcp_socket = socket;
                sdev->ud.sockfd = sockfd;
                sdev->ud.tcp_rx = tcp_rx;
                sdev->ud.tcp_tx = tcp_tx;
                sdev->ud.status = SDEV_ST_USED;
                spin_unlock_irq(&sdev->ud.lock);

                wake_up_process(sdev->ud.tcp_rx);
                wake_up_process(sdev->ud.tcp_tx);

                mutex_unlock(&sdev->ud.sysfs_lock);

        } else {
                dev_info(dev, "stub down\n");

                mutex_lock(&sdev->ud.sysfs_lock);

                spin_lock_irq(&sdev->ud.lock);
                if (sdev->ud.status != SDEV_ST_USED)
                        goto err;

                spin_unlock_irq(&sdev->ud.lock);

                usbip_event_add(&sdev->ud, SDEV_EVENT_DOWN);
                mutex_unlock(&sdev->ud.sysfs_lock);
        }

        return count;

sock_err:
        sockfd_put(socket);
err:
        spin_unlock_irq(&sdev->ud.lock);
unlock_mutex:
        mutex_unlock(&sdev->ud.sysfs_lock);
        return -EINVAL;
}
static DEVICE_ATTR_WO(usbip_sockfd);

static struct attribute *usbip_attrs[] = {
        &dev_attr_usbip_status.attr,
        &dev_attr_usbip_sockfd.attr,
        &dev_attr_usbip_debug.attr,
        NULL,
};
ATTRIBUTE_GROUPS(usbip);

static void stub_shutdown_connection(struct usbip_device *ud)
{
        struct stub_device *sdev = container_of(ud, struct stub_device, ud);

        /*
         * When removing an exported device, kernel panic sometimes occurred
         * and then EIP was sk_wait_data of stub_rx thread. Is this because
         * sk_wait_data returned though stub_rx thread was already finished by
         * step 1?
         */
        if (ud->tcp_socket) {
                dev_dbg(&sdev->udev->dev, "shutdown sockfd %d\n", ud->sockfd);
                kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR);
        }

        /* 1. stop threads */
        if (ud->tcp_rx) {
                kthread_stop_put(ud->tcp_rx);
                ud->tcp_rx = NULL;
        }
        if (ud->tcp_tx) {
                kthread_stop_put(ud->tcp_tx);
                ud->tcp_tx = NULL;
        }

        /*
         * 2. close the socket
         *
         * tcp_socket is freed after threads are killed so that usbip_xmit does
         * not touch NULL socket.
         */
        if (ud->tcp_socket) {
                sockfd_put(ud->tcp_socket);
                ud->tcp_socket = NULL;
                ud->sockfd = -1;
        }

        /* 3. free used data */
        stub_device_cleanup_urbs(sdev);

        /* 4. free stub_unlink */
        {
                unsigned long flags;
                struct stub_unlink *unlink, *tmp;

                spin_lock_irqsave(&sdev->priv_lock, flags);
                list_for_each_entry_safe(unlink, tmp, &sdev->unlink_tx, list) {
                        list_del(&unlink->list);
                        kfree(unlink);
                }
                list_for_each_entry_safe(unlink, tmp, &sdev->unlink_free,
                                         list) {
                        list_del(&unlink->list);
                        kfree(unlink);
                }
                spin_unlock_irqrestore(&sdev->priv_lock, flags);
        }
}

static void stub_device_reset(struct usbip_device *ud)
{
        struct stub_device *sdev = container_of(ud, struct stub_device, ud);
        struct usb_device *udev = sdev->udev;
        int ret;

        dev_dbg(&udev->dev, "device reset");

        ret = usb_lock_device_for_reset(udev, NULL);
        if (ret < 0) {
                dev_err(&udev->dev, "lock for reset\n");
                spin_lock_irq(&ud->lock);
                ud->status = SDEV_ST_ERROR;
                spin_unlock_irq(&ud->lock);
                return;
        }

        /* try to reset the device */
        ret = usb_reset_device(udev);
        usb_unlock_device(udev);

        spin_lock_irq(&ud->lock);
        if (ret) {
                dev_err(&udev->dev, "device reset\n");
                ud->status = SDEV_ST_ERROR;
        } else {
                dev_info(&udev->dev, "device reset\n");
                ud->status = SDEV_ST_AVAILABLE;
        }
        spin_unlock_irq(&ud->lock);
}

static void stub_device_unusable(struct usbip_device *ud)
{
        spin_lock_irq(&ud->lock);
        ud->status = SDEV_ST_ERROR;
        spin_unlock_irq(&ud->lock);
}

/**
 * stub_device_alloc - allocate a new stub_device struct
 * @udev: usb_device of a new device
 *
 * Allocates and initializes a new stub_device struct.
 */
static struct stub_device *stub_device_alloc(struct usb_device *udev)
{
        struct stub_device *sdev;
        int busnum = udev->bus->busnum;
        int devnum = udev->devnum;

        dev_dbg(&udev->dev, "allocating stub device");

        /* yes, it's a new device */
        sdev = kzalloc_obj(struct stub_device);
        if (!sdev)
                return NULL;

        sdev->udev = usb_get_dev(udev);

        /*
         * devid is defined with devnum when this driver is first allocated.
         * devnum may change later if a device is reset. However, devid never
         * changes during a usbip connection.
         */
        sdev->devid             = (busnum << 16) | devnum;
        sdev->ud.side           = USBIP_STUB;
        sdev->ud.status         = SDEV_ST_AVAILABLE;
        spin_lock_init(&sdev->ud.lock);
        mutex_init(&sdev->ud.sysfs_lock);
        sdev->ud.tcp_socket     = NULL;
        sdev->ud.sockfd         = -1;

        INIT_LIST_HEAD(&sdev->priv_init);
        INIT_LIST_HEAD(&sdev->priv_tx);
        INIT_LIST_HEAD(&sdev->priv_free);
        INIT_LIST_HEAD(&sdev->unlink_free);
        INIT_LIST_HEAD(&sdev->unlink_tx);
        spin_lock_init(&sdev->priv_lock);

        init_waitqueue_head(&sdev->tx_waitq);

        sdev->ud.eh_ops.shutdown = stub_shutdown_connection;
        sdev->ud.eh_ops.reset    = stub_device_reset;
        sdev->ud.eh_ops.unusable = stub_device_unusable;

        usbip_start_eh(&sdev->ud);

        dev_dbg(&udev->dev, "register new device\n");

        return sdev;
}

static void stub_device_free(struct stub_device *sdev)
{
        kfree(sdev);
}

static int stub_probe(struct usb_device *udev)
{
        struct stub_device *sdev = NULL;
        const char *udev_busid = dev_name(&udev->dev);
        struct bus_id_priv *busid_priv;
        int rc = 0;
        char save_status;

        dev_dbg(&udev->dev, "Enter probe\n");

        /* Not sure if this is our device. Allocate here to avoid
         * calling alloc while holding busid_table lock.
         */
        sdev = stub_device_alloc(udev);
        if (!sdev)
                return -ENOMEM;

        /* check we should claim or not by busid_table */
        busid_priv = get_busid_priv(udev_busid);
        if (!busid_priv || (busid_priv->status == STUB_BUSID_REMOV) ||
            (busid_priv->status == STUB_BUSID_OTHER)) {
                dev_info(&udev->dev,
                        "%s is not in match_busid table... skip!\n",
                        udev_busid);

                /*
                 * Return value should be ENODEV or ENOXIO to continue trying
                 * other matched drivers by the driver core.
                 * See driver_probe_device() in driver/base/dd.c
                 */
                rc = -ENODEV;
                if (!busid_priv)
                        goto sdev_free;

                goto call_put_busid_priv;
        }

        if (udev->descriptor.bDeviceClass == USB_CLASS_HUB) {
                dev_dbg(&udev->dev, "%s is a usb hub device... skip!\n",
                         udev_busid);
                rc = -ENODEV;
                goto call_put_busid_priv;
        }

        if (!strcmp(udev->bus->bus_name, "vhci_hcd")) {
                dev_dbg(&udev->dev,
                        "%s is attached on vhci_hcd... skip!\n",
                        udev_busid);

                rc = -ENODEV;
                goto call_put_busid_priv;
        }


        dev_info(&udev->dev,
                "usbip-host: register new device (bus %u dev %u)\n",
                udev->bus->busnum, udev->devnum);

        busid_priv->shutdown_busid = 0;

        /* set private data to usb_device */
        dev_set_drvdata(&udev->dev, sdev);

        busid_priv->sdev = sdev;
        busid_priv->udev = udev;

        save_status = busid_priv->status;
        busid_priv->status = STUB_BUSID_ALLOC;

        /* release the busid_lock */
        put_busid_priv(busid_priv);

        /*
         * Claim this hub port.
         * It doesn't matter what value we pass as owner
         * (struct dev_state) as long as it is unique.
         */
        rc = usb_hub_claim_port(udev->parent, udev->portnum,
                        (struct usb_dev_state *) udev);
        if (rc) {
                dev_dbg(&udev->dev, "unable to claim port\n");
                goto err_port;
        }

        return 0;

err_port:
        dev_set_drvdata(&udev->dev, NULL);

        /* we already have busid_priv, just lock busid_lock */
        spin_lock(&busid_priv->busid_lock);
        busid_priv->sdev = NULL;
        busid_priv->status = save_status;
        spin_unlock(&busid_priv->busid_lock);
        /* lock is released - go to free */
        goto sdev_free;

call_put_busid_priv:
        /* release the busid_lock */
        put_busid_priv(busid_priv);

sdev_free:
        usb_put_dev(udev);
        stub_device_free(sdev);

        return rc;
}

static void shutdown_busid(struct bus_id_priv *busid_priv)
{
        usbip_event_add(&busid_priv->sdev->ud, SDEV_EVENT_REMOVED);

        /* wait for the stop of the event handler */
        usbip_stop_eh(&busid_priv->sdev->ud);
}

/*
 * called in usb_disconnect() or usb_deregister()
 * but only if actconfig(active configuration) exists
 */
static void stub_disconnect(struct usb_device *udev)
{
        struct stub_device *sdev;
        const char *udev_busid = dev_name(&udev->dev);
        struct bus_id_priv *busid_priv;
        int rc;

        dev_dbg(&udev->dev, "Enter disconnect\n");

        busid_priv = get_busid_priv(udev_busid);
        if (!busid_priv) {
                BUG();
                return;
        }

        sdev = dev_get_drvdata(&udev->dev);

        /* get stub_device */
        if (!sdev) {
                dev_err(&udev->dev, "could not get device");
                /* release busid_lock */
                put_busid_priv(busid_priv);
                return;
        }

        dev_set_drvdata(&udev->dev, NULL);

        /* release busid_lock before call to remove device files */
        put_busid_priv(busid_priv);

        /*
         * NOTE: rx/tx threads are invoked for each usb_device.
         */

        /* release port */
        rc = usb_hub_release_port(udev->parent, udev->portnum,
                                  (struct usb_dev_state *) udev);
        /*
         * NOTE: If a HUB disconnect triggered disconnect of the down stream
         * device usb_hub_release_port will return -ENODEV so we can safely ignore
         * that error here.
         */
        if (rc && (rc != -ENODEV)) {
                dev_dbg(&udev->dev, "unable to release port (%i)\n", rc);
                return;
        }

        /* If usb reset is called from event handler */
        if (usbip_in_eh(current))
                return;

        /* we already have busid_priv, just lock busid_lock */
        spin_lock(&busid_priv->busid_lock);
        if (!busid_priv->shutdown_busid)
                busid_priv->shutdown_busid = 1;
        /* release busid_lock */
        spin_unlock(&busid_priv->busid_lock);

        /* shutdown the current connection */
        shutdown_busid(busid_priv);

        usb_put_dev(sdev->udev);

        /* we already have busid_priv, just lock busid_lock */
        spin_lock(&busid_priv->busid_lock);
        /* free sdev */
        busid_priv->sdev = NULL;
        stub_device_free(sdev);

        if (busid_priv->status == STUB_BUSID_ALLOC)
                busid_priv->status = STUB_BUSID_ADDED;
        /* release busid_lock */
        spin_unlock(&busid_priv->busid_lock);
        return;
}

#ifdef CONFIG_PM

/* These functions need usb_port_suspend and usb_port_resume,
 * which reside in drivers/usb/core/usb.h. Skip for now. */

static int stub_suspend(struct usb_device *udev, pm_message_t message)
{
        dev_dbg(&udev->dev, "stub_suspend\n");

        return 0;
}

static int stub_resume(struct usb_device *udev, pm_message_t message)
{
        dev_dbg(&udev->dev, "stub_resume\n");

        return 0;
}

#endif  /* CONFIG_PM */

struct usb_device_driver stub_driver = {
        .name           = "usbip-host",
        .probe          = stub_probe,
        .disconnect     = stub_disconnect,
#ifdef CONFIG_PM
        .suspend        = stub_suspend,
        .resume         = stub_resume,
#endif
        .supports_autosuspend   =       0,
        .dev_groups     = usbip_groups,
};