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

#include <linux/kthread.h>
#include <linux/minmax.h>
#include <linux/socket.h>
#include <linux/scatterlist.h>

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

/* be in spin_lock_irqsave(&sdev->priv_lock, flags) */
void stub_enqueue_ret_unlink(struct stub_device *sdev, __u32 seqnum,
                             __u32 status)
{
        struct stub_unlink *unlink;

        unlink = kzalloc_obj(struct stub_unlink, GFP_ATOMIC);
        if (!unlink) {
                usbip_event_add(&sdev->ud, VDEV_EVENT_ERROR_MALLOC);
                return;
        }

        unlink->seqnum = seqnum;
        unlink->status = status;

        list_add_tail(&unlink->list, &sdev->unlink_tx);
}

/**
 * stub_complete - completion handler of a usbip urb
 * @urb: pointer to the urb completed
 *
 * When a urb has completed, the USB core driver calls this function mostly in
 * the interrupt context. To return the result of a urb, the completed urb is
 * linked to the pending list of returning.
 *
 */
void stub_complete(struct urb *urb)
{
        struct stub_priv *priv = (struct stub_priv *) urb->context;
        struct stub_device *sdev = priv->sdev;
        unsigned long flags;

        usbip_dbg_stub_tx("complete! status %d\n", urb->status);

        switch (urb->status) {
        case 0:
                /* OK */
                break;
        case -ENOENT:
                dev_info(&urb->dev->dev,
                         "stopped by a call to usb_kill_urb() because of cleaning up a virtual connection\n");
                return;
        case -ECONNRESET:
                dev_dbg(&urb->dev->dev,
                        "unlinked by a call to usb_unlink_urb()\n");
                break;
        case -EPIPE:
                dev_info(&urb->dev->dev, "endpoint %d is stalled\n",
                         usb_pipeendpoint(urb->pipe));
                break;
        case -ESHUTDOWN:
                dev_info(&urb->dev->dev, "device removed?\n");
                break;
        default:
                dev_info(&urb->dev->dev,
                         "urb completion with non-zero status %d\n",
                         urb->status);
                break;
        }

        /*
         * If the server breaks single SG request into the several URBs, the
         * URBs must be reassembled before sending completed URB to the vhci.
         * Don't wake up the tx thread until all the URBs are completed.
         */
        if (priv->sgl) {
                priv->completed_urbs++;

                /* Only save the first error status */
                if (urb->status && !priv->urb_status)
                        priv->urb_status = urb->status;

                if (priv->completed_urbs < priv->num_urbs)
                        return;
        }

        /* link a urb to the queue of tx. */
        spin_lock_irqsave(&sdev->priv_lock, flags);
        if (sdev->ud.tcp_socket == NULL) {
                usbip_dbg_stub_tx("ignore urb for closed connection\n");
                /* It will be freed in stub_device_cleanup_urbs(). */
        } else if (priv->unlinking) {
                stub_enqueue_ret_unlink(sdev, priv->seqnum, urb->status);
                stub_free_priv_and_urb(priv);
        } else {
                list_move_tail(&priv->list, &sdev->priv_tx);
        }
        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        /* wake up tx_thread */
        wake_up(&sdev->tx_waitq);
}

static inline void setup_base_pdu(struct usbip_header_basic *base,
                                  __u32 command, __u32 seqnum)
{
        base->command   = command;
        base->seqnum    = seqnum;
        base->devid     = 0;
        base->ep        = 0;
        base->direction = 0;
}

static void setup_ret_submit_pdu(struct usbip_header *rpdu, struct urb *urb)
{
        struct stub_priv *priv = (struct stub_priv *) urb->context;

        setup_base_pdu(&rpdu->base, USBIP_RET_SUBMIT, priv->seqnum);
        usbip_pack_pdu(rpdu, urb, USBIP_RET_SUBMIT, 1);
}

static void setup_ret_unlink_pdu(struct usbip_header *rpdu,
                                 struct stub_unlink *unlink)
{
        setup_base_pdu(&rpdu->base, USBIP_RET_UNLINK, unlink->seqnum);
        rpdu->u.ret_unlink.status = unlink->status;
}

static struct stub_priv *dequeue_from_priv_tx(struct stub_device *sdev)
{
        unsigned long flags;
        struct stub_priv *priv, *tmp;

        spin_lock_irqsave(&sdev->priv_lock, flags);

        list_for_each_entry_safe(priv, tmp, &sdev->priv_tx, list) {
                list_move_tail(&priv->list, &sdev->priv_free);
                spin_unlock_irqrestore(&sdev->priv_lock, flags);
                return priv;
        }

        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        return NULL;
}

static int stub_send_ret_submit(struct stub_device *sdev)
{
        unsigned long flags;
        struct stub_priv *priv, *tmp;

        struct msghdr msg;
        size_t txsize;

        size_t total_size = 0;

        while ((priv = dequeue_from_priv_tx(sdev)) != NULL) {
                struct urb *urb = priv->urbs[0];
                struct usbip_header pdu_header;
                struct usbip_iso_packet_descriptor *iso_buffer = NULL;
                struct kvec *iov = NULL;
                struct scatterlist *sg;
                u32 actual_length = 0;
                int iovnum = 0;
                int ret;
                int i;

                txsize = 0;
                memset(&pdu_header, 0, sizeof(pdu_header));
                memset(&msg, 0, sizeof(msg));

                if (urb->actual_length > 0 && !urb->transfer_buffer &&
                   !urb->num_sgs) {
                        dev_err(&sdev->udev->dev,
                                "urb: actual_length %d transfer_buffer null\n",
                                urb->actual_length);
                        return -1;
                }

                if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS)
                        iovnum = 2 + urb->number_of_packets;
                else if (usb_pipein(urb->pipe) && urb->actual_length > 0 &&
                        urb->num_sgs)
                        iovnum = 1 + urb->num_sgs;
                else if (usb_pipein(urb->pipe) && priv->sgl)
                        iovnum = 1 + priv->num_urbs;
                else
                        iovnum = 2;

                iov = kzalloc_objs(struct kvec, iovnum);

                if (!iov) {
                        usbip_event_add(&sdev->ud, SDEV_EVENT_ERROR_MALLOC);
                        return -1;
                }

                iovnum = 0;

                /* 1. setup usbip_header */
                setup_ret_submit_pdu(&pdu_header, urb);
                usbip_dbg_stub_tx("setup txdata seqnum: %u\n",
                                  pdu_header.base.seqnum);

                if (priv->sgl) {
                        for (i = 0; i < priv->num_urbs; i++)
                                actual_length += priv->urbs[i]->actual_length;

                        pdu_header.u.ret_submit.status = priv->urb_status;
                        pdu_header.u.ret_submit.actual_length = actual_length;
                }

                usbip_header_correct_endian(&pdu_header, 1);

                iov[iovnum].iov_base = &pdu_header;
                iov[iovnum].iov_len  = sizeof(pdu_header);
                iovnum++;
                txsize += sizeof(pdu_header);

                /* 2. setup transfer buffer */
                if (usb_pipein(urb->pipe) && priv->sgl) {
                        /* If the server split a single SG request into several
                         * URBs because the server's HCD doesn't support SG,
                         * reassemble the split URB buffers into a single
                         * return command.
                         */
                        for (i = 0; i < priv->num_urbs; i++) {
                                iov[iovnum].iov_base =
                                        priv->urbs[i]->transfer_buffer;
                                iov[iovnum].iov_len =
                                        priv->urbs[i]->actual_length;
                                iovnum++;
                        }
                        txsize += actual_length;
                } else if (usb_pipein(urb->pipe) &&
                    usb_pipetype(urb->pipe) != PIPE_ISOCHRONOUS &&
                    urb->actual_length > 0) {
                        if (urb->num_sgs) {
                                unsigned int copy = urb->actual_length;
                                unsigned int size;

                                for_each_sg(urb->sg, sg, urb->num_sgs, i) {
                                        if (copy == 0)
                                                break;

                                        size = min(copy, sg->length);
                                        iov[iovnum].iov_base = sg_virt(sg);
                                        iov[iovnum].iov_len = size;

                                        iovnum++;
                                        copy -= size;
                                }
                        } else {
                                iov[iovnum].iov_base = urb->transfer_buffer;
                                iov[iovnum].iov_len  = urb->actual_length;
                                iovnum++;
                        }
                        txsize += urb->actual_length;
                } else if (usb_pipein(urb->pipe) &&
                           usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS) {
                        /*
                         * For isochronous packets: actual length is the sum of
                         * the actual length of the individual, packets, but as
                         * the packet offsets are not changed there will be
                         * padding between the packets. To optimally use the
                         * bandwidth the padding is not transmitted.
                         */

                        int i;

                        for (i = 0; i < urb->number_of_packets; i++) {
                                iov[iovnum].iov_base = urb->transfer_buffer +
                                        urb->iso_frame_desc[i].offset;
                                iov[iovnum].iov_len =
                                        urb->iso_frame_desc[i].actual_length;
                                iovnum++;
                                txsize += urb->iso_frame_desc[i].actual_length;
                        }

                        if (txsize != sizeof(pdu_header) + urb->actual_length) {
                                dev_err(&sdev->udev->dev,
                                        "actual length of urb %d does not match iso packet sizes %zu\n",
                                        urb->actual_length,
                                        txsize-sizeof(pdu_header));
                                kfree(iov);
                                usbip_event_add(&sdev->ud,
                                                SDEV_EVENT_ERROR_TCP);
                                return -1;
                        }
                }

                /* 3. setup iso_packet_descriptor */
                if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS) {
                        ssize_t len = 0;

                        iso_buffer = usbip_alloc_iso_desc_pdu(urb, &len);
                        if (!iso_buffer) {
                                usbip_event_add(&sdev->ud,
                                                SDEV_EVENT_ERROR_MALLOC);
                                kfree(iov);
                                return -1;
                        }

                        iov[iovnum].iov_base = iso_buffer;
                        iov[iovnum].iov_len  = len;
                        txsize += len;
                        iovnum++;
                }

                ret = kernel_sendmsg(sdev->ud.tcp_socket, &msg,
                                                iov,  iovnum, txsize);
                if (ret != txsize) {
                        dev_err(&sdev->udev->dev,
                                "sendmsg failed!, retval %d for %zd\n",
                                ret, txsize);
                        kfree(iov);
                        kfree(iso_buffer);
                        usbip_event_add(&sdev->ud, SDEV_EVENT_ERROR_TCP);
                        return -1;
                }

                kfree(iov);
                kfree(iso_buffer);

                total_size += txsize;
        }

        spin_lock_irqsave(&sdev->priv_lock, flags);
        list_for_each_entry_safe(priv, tmp, &sdev->priv_free, list) {
                stub_free_priv_and_urb(priv);
        }
        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        return total_size;
}

static struct stub_unlink *dequeue_from_unlink_tx(struct stub_device *sdev)
{
        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_move_tail(&unlink->list, &sdev->unlink_free);
                spin_unlock_irqrestore(&sdev->priv_lock, flags);
                return unlink;
        }

        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        return NULL;
}

static int stub_send_ret_unlink(struct stub_device *sdev)
{
        unsigned long flags;
        struct stub_unlink *unlink, *tmp;

        struct msghdr msg;
        struct kvec iov[1];
        size_t txsize;

        size_t total_size = 0;

        while ((unlink = dequeue_from_unlink_tx(sdev)) != NULL) {
                int ret;
                struct usbip_header pdu_header;

                txsize = 0;
                memset(&pdu_header, 0, sizeof(pdu_header));
                memset(&msg, 0, sizeof(msg));
                memset(&iov, 0, sizeof(iov));

                usbip_dbg_stub_tx("setup ret unlink %lu\n", unlink->seqnum);

                /* 1. setup usbip_header */
                setup_ret_unlink_pdu(&pdu_header, unlink);
                usbip_header_correct_endian(&pdu_header, 1);

                iov[0].iov_base = &pdu_header;
                iov[0].iov_len  = sizeof(pdu_header);
                txsize += sizeof(pdu_header);

                ret = kernel_sendmsg(sdev->ud.tcp_socket, &msg, iov,
                                     1, txsize);
                if (ret != txsize) {
                        dev_err(&sdev->udev->dev,
                                "sendmsg failed!, retval %d for %zd\n",
                                ret, txsize);
                        usbip_event_add(&sdev->ud, SDEV_EVENT_ERROR_TCP);
                        return -1;
                }

                usbip_dbg_stub_tx("send txdata\n");
                total_size += txsize;
        }

        spin_lock_irqsave(&sdev->priv_lock, flags);

        list_for_each_entry_safe(unlink, tmp, &sdev->unlink_free, list) {
                list_del(&unlink->list);
                kfree(unlink);
        }

        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        return total_size;
}

int stub_tx_loop(void *data)
{
        struct usbip_device *ud = data;
        struct stub_device *sdev = container_of(ud, struct stub_device, ud);

        while (!kthread_should_stop()) {
                if (usbip_event_happened(ud))
                        break;

                /*
                 * send_ret_submit comes earlier than send_ret_unlink.  stub_rx
                 * looks at only priv_init queue. If the completion of a URB is
                 * earlier than the receive of CMD_UNLINK, priv is moved to
                 * priv_tx queue and stub_rx does not find the target priv. In
                 * this case, vhci_rx receives the result of the submit request
                 * and then receives the result of the unlink request. The
                 * result of the submit is given back to the usbcore as the
                 * completion of the unlink request. The request of the
                 * unlink is ignored. This is ok because a driver who calls
                 * usb_unlink_urb() understands the unlink was too late by
                 * getting the status of the given-backed URB which has the
                 * status of usb_submit_urb().
                 */
                if (stub_send_ret_submit(sdev) < 0)
                        break;

                if (stub_send_ret_unlink(sdev) < 0)
                        break;

                wait_event_interruptible(sdev->tx_waitq,
                                         (!list_empty(&sdev->priv_tx) ||
                                          !list_empty(&sdev->unlink_tx) ||
                                          kthread_should_stop()));
        }

        return 0;
}