usbip: vudc: Add vudc_tx

This file contains functions for returning requests to the client.
It also has functions that add requests completed in vudc_rx and
vudc_transfer to the return queue.

This commit is a result of cooperation between Samsung R&D Institute
Poland and Open Operating Systems Student Society at University
of Warsaw (O2S3@UW) consisting of:

    Igor Kotrasinski <ikotrasinsk@gmail.com>
    Karol Kosik <karo9@interia.eu>
    Ewelina Kosmider <3w3lfin@gmail.com>
    Dawid Lazarczyk <lazarczyk.dawid@gmail.com>
    Piotr Szulc <ps347277@students.mimuw.edu.pl>

Tutor and project owner:
    Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Igor Kotrasinski <i.kotrasinsk@samsung.com>
Signed-off-by: Karol Kosik <karo9@interia.eu>
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/usbip/vudc_tx.c

+/*
+ * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
+ *
+ * This program 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 program 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <net/sock.h>
+#include <linux/list.h>
+#include <linux/kthread.h>
+
+#include "usbip_common.h"
+#include "vudc.h"
+
+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 urbp *urb_p)
+{
+	setup_base_pdu(&rpdu->base, USBIP_RET_SUBMIT, urb_p->seqnum);
+	usbip_pack_pdu(rpdu, urb_p->urb, USBIP_RET_SUBMIT, 1);
+}
+
+static void setup_ret_unlink_pdu(struct usbip_header *rpdu,
+				 struct v_unlink *unlink)
+{
+	setup_base_pdu(&rpdu->base, USBIP_RET_UNLINK, unlink->seqnum);
+	rpdu->u.ret_unlink.status = unlink->status;
+}
+
+static int v_send_ret_unlink(struct vudc *udc, struct v_unlink *unlink)
+{
+	struct msghdr msg;
+	struct kvec iov[1];
+	size_t txsize;
+
+	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));
+
+	/* 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(udc->ud.tcp_socket, &msg, iov,
+			     1, txsize);
+	if (ret != txsize) {
+		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_TCP);
+		if (ret >= 0)
+			return -EPIPE;
+		return ret;
+	}
+	kfree(unlink);
+
+	return txsize;
+}
+
+static int v_send_ret_submit(struct vudc *udc, struct urbp *urb_p)
+{
+	struct urb *urb = urb_p->urb;
+	struct usbip_header pdu_header;
+	struct usbip_iso_packet_descriptor *iso_buffer = NULL;
+	struct kvec *iov = NULL;
+	int iovnum = 0;
+	int ret = 0;
+	size_t txsize;
+	struct msghdr msg;
+
+	txsize = 0;
+	memset(&pdu_header, 0, sizeof(pdu_header));
+	memset(&msg, 0, sizeof(msg));
+
+	if (urb_p->type == USB_ENDPOINT_XFER_ISOC)
+		iovnum = 2 + urb->number_of_packets;
+	else
+		iovnum = 2;
+
+	iov = kcalloc(iovnum, sizeof(*iov), GFP_KERNEL);
+	if (!iov) {
+		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_MALLOC);
+		ret = -ENOMEM;
+		goto out;
+	}
+	iovnum = 0;
+
+	/* 1. setup usbip_header */
+	setup_ret_submit_pdu(&pdu_header, urb_p);
+	usbip_dbg_stub_tx("setup txdata seqnum: %d urb: %p\n",
+			  pdu_header.base.seqnum, urb);
+	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 (urb_p->type != USB_ENDPOINT_XFER_ISOC &&
+	    usb_pipein(urb->pipe) && urb->actual_length > 0) {
+		iov[iovnum].iov_base = urb->transfer_buffer;
+		iov[iovnum].iov_len  = urb->actual_length;
+		iovnum++;
+		txsize += urb->actual_length;
+	} else if (urb_p->type == USB_ENDPOINT_XFER_ISOC &&
+		usb_pipein(urb->pipe)) {
+		/* FIXME - copypasted from stub_tx, refactor */
+		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) {
+			usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_TCP);
+			ret = -EPIPE;
+			goto out;
+		}
+	}
+	/* else - no buffer to send */
+
+	/* 3. setup iso_packet_descriptor */
+	if (urb_p->type == USB_ENDPOINT_XFER_ISOC) {
+		ssize_t len = 0;
+
+		iso_buffer = usbip_alloc_iso_desc_pdu(urb, &len);
+		if (!iso_buffer) {
+			usbip_event_add(&udc->ud,
+					VUDC_EVENT_ERROR_MALLOC);
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		iov[iovnum].iov_base = iso_buffer;
+		iov[iovnum].iov_len  = len;
+		txsize += len;
+		iovnum++;
+	}
+
+	ret = kernel_sendmsg(udc->ud.tcp_socket, &msg,
+						iov,  iovnum, txsize);
+	if (ret != txsize) {
+		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_TCP);
+		if (ret >= 0)
+			ret = -EPIPE;
+		goto out;
+	}
+
+out:
+	kfree(iov);
+	kfree(iso_buffer);
+	free_urbp_and_urb(urb_p);
+	if (ret < 0)
+		return ret;
+	return txsize;
+}
+
+static int v_send_ret(struct vudc *udc)
+{
+	unsigned long flags;
+	struct tx_item *txi;
+	size_t total_size = 0;
+	int ret = 0;
+
+	spin_lock_irqsave(&udc->lock_tx, flags);
+	while (!list_empty(&udc->tx_queue)) {
+		txi = list_first_entry(&udc->tx_queue, struct tx_item,
+				       tx_entry);
+		list_del(&txi->tx_entry);
+		spin_unlock_irqrestore(&udc->lock_tx, flags);
+
+		switch (txi->type) {
+		case TX_SUBMIT:
+			ret = v_send_ret_submit(udc, txi->s);
+			break;
+		case TX_UNLINK:
+			ret = v_send_ret_unlink(udc, txi->u);
+			break;
+		}
+		kfree(txi);
+
+		if (ret < 0)
+			return ret;
+
+		total_size += ret;
+
+		spin_lock_irqsave(&udc->lock_tx, flags);
+	}
+
+	spin_unlock_irqrestore(&udc->lock_tx, flags);
+	return total_size;
+}
+
+
+int v_tx_loop(void *data)
+{
+	struct usbip_device *ud = (struct usbip_device *) data;
+	struct vudc *udc = container_of(ud, struct vudc, ud);
+	int ret;
+
+	while (!kthread_should_stop()) {
+		if (usbip_event_happened(&udc->ud))
+			break;
+		ret = v_send_ret(udc);
+		if (ret < 0) {
+			pr_warn("v_tx exit with error %d", ret);
+			break;
+		}
+		wait_event_interruptible(udc->tx_waitq,
+					 (!list_empty(&udc->tx_queue) ||
+					 kthread_should_stop()));
+	}
+
+	return 0;
+}
+
+/* called with spinlocks held */
+void v_enqueue_ret_unlink(struct vudc *udc, __u32 seqnum, __u32 status)
+{
+	struct tx_item *txi;
+	struct v_unlink *unlink;
+
+	txi = kzalloc(sizeof(*txi), GFP_ATOMIC);
+	if (!txi) {
+		usbip_event_add(&udc->ud, VDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+	unlink = kzalloc(sizeof(*unlink), GFP_ATOMIC);
+	if (!unlink) {
+		kfree(txi);
+		usbip_event_add(&udc->ud, VDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+
+	unlink->seqnum = seqnum;
+	unlink->status = status;
+	txi->type = TX_UNLINK;
+	txi->u = unlink;
+
+	list_add_tail(&txi->tx_entry, &udc->tx_queue);
+}
+
+/* called with spinlocks held */
+void v_enqueue_ret_submit(struct vudc *udc, struct urbp *urb_p)
+{
+	struct tx_item *txi;
+
+	txi = kzalloc(sizeof(*txi), GFP_ATOMIC);
+	if (!txi) {
+		usbip_event_add(&udc->ud, VDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+
+	txi->type = TX_SUBMIT;
+	txi->s = urb_p;
+
+	list_add_tail(&txi->tx_entry, &udc->tx_queue);
+}