vhci_rx.c

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/*
 * Copyright (C) 2003-2008 Takahiro Hirofuchi
 *
 * This 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.
 *
 * This is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 * USA.
 */

#include <linux/kthread.h>
#include <linux/slab.h>

#include "usbip_common.h"
#include "vhci.h"

/* get URB from transmitted urb queue. caller must hold vdev->priv_lock */
struct urb *pickup_urb_and_free_priv(struct vhci_device *vdev, __u32 seqnum)
{
    struct vhci_priv *priv, *tmp;
    struct urb *urb = NULL;
    int status;

    list_for_each_entry_safe(priv, tmp, &vdev->priv_rx, list) {
        if (priv->seqnum == seqnum) {
            urb = priv->urb;
            status = urb->status;

            usbip_dbg_vhci_rx("find urb %p vurb %p seqnum %u\n",
                      urb, priv, seqnum);

            /* TODO: fix logic here to improve indent situtation */
            if (status != -EINPROGRESS) {
                if (status == -ENOENT ||
                    status == -ECONNRESET)
                    dev_info(&urb->dev->dev,
                         "urb %p was unlinked "
                         "%ssynchronuously.\n", urb,
                         status == -ENOENT ? "" : "a");
                else
                    dev_info(&urb->dev->dev,
                         "urb %p may be in a error, "
                         "status %d\n", urb, status);
            }

            list_del(&priv->list);
            kfree(priv);
            urb->hcpriv = NULL;

            break;
        }
    }

    return urb;
}

static void vhci_recv_ret_submit(struct vhci_device *vdev,
                 struct usbip_header *pdu)
{
    struct usbip_device *ud = &vdev->ud;
    struct urb *urb;
    unsigned long flags;

    spin_lock(&vdev->priv_lock);
    urb = pickup_urb_and_free_priv(vdev, pdu->base.seqnum);
    spin_unlock(&vdev->priv_lock);

    if (!urb) {
        pr_err("cannot find a urb of seqnum %u\n", pdu->base.seqnum);
        pr_info("max seqnum %d\n",
            atomic_read(&the_controller->seqnum));
        usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
        return;
    }

    /* unpack the pdu to a urb */
    usbip_pack_pdu(pdu, urb, USBIP_RET_SUBMIT, 0);

    /* recv transfer buffer */
    if (usbip_recv_xbuff(ud, urb) < 0)
        return;

    /* recv iso_packet_descriptor */
    if (usbip_recv_iso(ud, urb) < 0)
        return;

    /* restore the padding in iso packets */
    usbip_pad_iso(ud, urb);

    if (usbip_dbg_flag_vhci_rx)
        usbip_dump_urb(urb);

    usbip_dbg_vhci_rx("now giveback urb %p\n", urb);

    spin_lock_irqsave(&the_controller->lock, flags);
    usb_hcd_unlink_urb_from_ep(vhci_to_hcd(the_controller), urb);
    spin_unlock_irqrestore(&the_controller->lock, flags);

    usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb, urb->status);

    usbip_dbg_vhci_rx("Leave\n");

    return;
}

static struct vhci_unlink *dequeue_pending_unlink(struct vhci_device *vdev,
                          struct usbip_header *pdu)
{
    struct vhci_unlink *unlink, *tmp;

    spin_lock(&vdev->priv_lock);

    list_for_each_entry_safe(unlink, tmp, &vdev->unlink_rx, list) {
        pr_info("unlink->seqnum %lu\n", unlink->seqnum);
        if (unlink->seqnum == pdu->base.seqnum) {
            usbip_dbg_vhci_rx("found pending unlink, %lu\n",
                      unlink->seqnum);
            list_del(&unlink->list);

            spin_unlock(&vdev->priv_lock);
            return unlink;
        }
    }

    spin_unlock(&vdev->priv_lock);

    return NULL;
}

static void vhci_recv_ret_unlink(struct vhci_device *vdev,
                 struct usbip_header *pdu)
{
    struct vhci_unlink *unlink;
    struct urb *urb;
    unsigned long flags;

    usbip_dump_header(pdu);

    unlink = dequeue_pending_unlink(vdev, pdu);
    if (!unlink) {
        pr_info("cannot find the pending unlink %u\n",
            pdu->base.seqnum);
        return;
    }

    spin_lock(&vdev->priv_lock);
    urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
    spin_unlock(&vdev->priv_lock);

    if (!urb) {
        /*
         * I get the result of a unlink request. But, it seems that I
         * already received the result of its submit result and gave
         * back the URB.
         */
        pr_info("the urb (seqnum %d) was already given back\n",
            pdu->base.seqnum);
    } else {
        usbip_dbg_vhci_rx("now giveback urb %p\n", urb);

        /* If unlink is succeed, status is -ECONNRESET */
        urb->status = pdu->u.ret_unlink.status;
        pr_info("urb->status %d\n", urb->status);

        spin_lock_irqsave(&the_controller->lock, flags);
        usb_hcd_unlink_urb_from_ep(vhci_to_hcd(the_controller), urb);
        spin_unlock_irqrestore(&the_controller->lock, flags);

        usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb,
                     urb->status);
    }

    kfree(unlink);
}

static int vhci_priv_tx_empty(struct vhci_device *vdev)
{
    int empty = 0;

    spin_lock(&vdev->priv_lock);
    empty = list_empty(&vdev->priv_rx);
    spin_unlock(&vdev->priv_lock);

    return empty;
}

/* recv a pdu */
static void vhci_rx_pdu(struct usbip_device *ud)
{
    int ret;
    struct usbip_header pdu;
    struct vhci_device *vdev = container_of(ud, struct vhci_device, ud);

    usbip_dbg_vhci_rx("Enter\n");

    memset(&pdu, 0, sizeof(pdu));

    /* 1. receive a pdu header */
    ret = usbip_recv(ud->tcp_socket, &pdu, sizeof(pdu));
    if (ret < 0) {
        if (ret == -ECONNRESET)
            pr_info("connection reset by peer\n");
        else if (ret == -EAGAIN) {
            /* ignore if connection was idle */
            if (vhci_priv_tx_empty(vdev))
                return;
            pr_info("connection timed out with pending urbs\n");
        } else if (ret != -ERESTARTSYS)
            pr_info("xmit failed %d\n", ret);

        usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
        return;
    }
    if (ret == 0) {
        pr_info("connection closed");
        usbip_event_add(ud, VDEV_EVENT_DOWN);
        return;
    }
    if (ret != sizeof(pdu)) {
        pr_err("received pdu size is %d, should be %d\n", ret,
               (unsigned int)sizeof(pdu));
        usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
        return;
    }

    usbip_header_correct_endian(&pdu, 0);

    if (usbip_dbg_flag_vhci_rx)
        usbip_dump_header(&pdu);

    switch (pdu.base.command) {
    case USBIP_RET_SUBMIT:
        vhci_recv_ret_submit(vdev, &pdu);
        break;
    case USBIP_RET_UNLINK:
        vhci_recv_ret_unlink(vdev, &pdu);
        break;
    default:
        /* NOT REACHED */
        pr_err("unknown pdu %u\n", pdu.base.command);
        usbip_dump_header(&pdu);
        usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
        break;
    }
}

int vhci_rx_loop(void *data)
{
    struct usbip_device *ud = data;

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

        vhci_rx_pdu(ud);
    }

    return 0;
}