text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * Copyright (C) 2003-2008 Takahiro Hirofuchi
   */
  
  #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)
  			continue;
  
  		urb = priv->urb;
  		status = urb->status;
  
  		usbip_dbg_vhci_rx("find urb seqnum %u\n", seqnum);
  
  		switch (status) {
  		case -ENOENT:
  			/* fall through */
  		case -ECONNRESET:
  			dev_dbg(&urb->dev->dev,
  				 "urb seq# %u was unlinked %ssynchronously\n",
  				 seqnum, status == -ENOENT ? "" : "a");
  			break;
  		case -EINPROGRESS:
  			/* no info output */
  			break;
  		default:
  			dev_dbg(&urb->dev->dev,
  				 "urb seq# %u may be in a error, status %d\n",
  				 seqnum, 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 vhci_hcd *vhci_hcd = vdev_to_vhci_hcd(vdev);
  	struct vhci *vhci = vhci_hcd->vhci;
  	struct usbip_device *ud = &vdev->ud;
  	struct urb *urb;
  	unsigned long flags;
  
  	spin_lock_irqsave(&vdev->priv_lock, flags);
  	urb = pickup_urb_and_free_priv(vdev, pdu->base.seqnum);
  	spin_unlock_irqrestore(&vdev->priv_lock, flags);
  
  	if (!urb) {
  		pr_err("cannot find a urb of seqnum %u max seqnum %d\n",
  			pdu->base.seqnum,
  			atomic_read(&vhci_hcd->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 %u\n", pdu->base.seqnum);
  
  	spin_lock_irqsave(&vhci->lock, flags);
  	usb_hcd_unlink_urb_from_ep(vhci_hcd_to_hcd(vhci_hcd), urb);
  	spin_unlock_irqrestore(&vhci->lock, flags);
  
  	usb_hcd_giveback_urb(vhci_hcd_to_hcd(vhci_hcd), urb, urb->status);
  
  	usbip_dbg_vhci_rx("Leave\n");
  }
  
  static struct vhci_unlink *dequeue_pending_unlink(struct vhci_device *vdev,
  						  struct usbip_header *pdu)
  {
  	struct vhci_unlink *unlink, *tmp;
  	unsigned long flags;
  
  	spin_lock_irqsave(&vdev->priv_lock, flags);
  
  	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_irqrestore(&vdev->priv_lock, flags);
  			return unlink;
  		}
  	}
  
  	spin_unlock_irqrestore(&vdev->priv_lock, flags);
  
  	return NULL;
  }
  
  static void vhci_recv_ret_unlink(struct vhci_device *vdev,
  				 struct usbip_header *pdu)
  {
  	struct vhci_hcd *vhci_hcd = vdev_to_vhci_hcd(vdev);
  	struct vhci *vhci = vhci_hcd->vhci;
  	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_irqsave(&vdev->priv_lock, flags);
  	urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
  	spin_unlock_irqrestore(&vdev->priv_lock, flags);
  
  	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 %d\n", pdu->base.seqnum);
  
  		/* If unlink is successful, status is -ECONNRESET */
  		urb->status = pdu->u.ret_unlink.status;
  		pr_info("urb->status %d\n", urb->status);
  
  		spin_lock_irqsave(&vhci->lock, flags);
  		usb_hcd_unlink_urb_from_ep(vhci_hcd_to_hcd(vhci_hcd), urb);
  		spin_unlock_irqrestore(&vhci->lock, flags);
  
  		usb_hcd_giveback_urb(vhci_hcd_to_hcd(vhci_hcd), urb, urb->status);
  	}
  
  	kfree(unlink);
  }
  
  static int vhci_priv_tx_empty(struct vhci_device *vdev)
  {
  	int empty = 0;
  	unsigned long flags;
  
  	spin_lock_irqsave(&vdev->priv_lock, flags);
  	empty = list_empty(&vdev->priv_rx);
  	spin_unlock_irqrestore(&vdev->priv_lock, flags);
  
  	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));
  
  	/* 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;
  }
  