linux/drivers/xen/xenbus/xenbus_comms.c

/******************************************************************************
 * xenbus_comms.c
 *
 * Low level code to talks to Xen Store: ringbuffer and event channel.
 *
 * Copyright (C) 2005 Rusty Russell, IBM Corporation
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#define pr_fmt(fmt) …

#include <linux/wait.h>
#include <linux/interrupt.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/err.h>
#include <xen/xenbus.h>
#include <asm/xen/hypervisor.h>
#include <xen/events.h>
#include <xen/page.h>
#include "xenbus.h"

/* A list of replies. Currently only one will ever be outstanding. */
LIST_HEAD(…);

/* A list of write requests. */
LIST_HEAD(…);
DECLARE_WAIT_QUEUE_HEAD(…);
DEFINE_MUTEX(…) …;

/* Protect xenbus reader thread against save/restore. */
DEFINE_MUTEX(…) …;

static int xenbus_irq;
static struct task_struct *xenbus_task;

static irqreturn_t wake_waiting(int irq, void *unused)
{ … }

static int check_indexes(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod)
{ … }

static void *get_output_chunk(XENSTORE_RING_IDX cons,
			      XENSTORE_RING_IDX prod,
			      char *buf, uint32_t *len)
{ … }

static const void *get_input_chunk(XENSTORE_RING_IDX cons,
				   XENSTORE_RING_IDX prod,
				   const char *buf, uint32_t *len)
{ … }

static int xb_data_to_write(void)
{ … }

/**
 * xb_write - low level write
 * @data: buffer to send
 * @len: length of buffer
 *
 * Returns number of bytes written or -err.
 */
static int xb_write(const void *data, unsigned int len)
{ … }

static int xb_data_to_read(void)
{ … }

static int xb_read(void *data, unsigned int len)
{ … }

static int process_msg(void)
{ … }

static int process_writes(void)
{ … }

static int xb_thread_work(void)
{ … }

static int xenbus_thread(void *unused)
{ … }

/**
 * xb_init_comms - Set up interrupt handler off store event channel.
 */
int xb_init_comms(void)
{ … }

void xb_deinit_comms(void)
{ … }