![Sachin Kamat](/assets/img/avatar_default.png)
asm/xen/hypervisor.h was included twice. Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
948 lines
21 KiB
C
948 lines
21 KiB
C
/******************************************************************************
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* xenbus_xs.c
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*
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* This is the kernel equivalent of the "xs" library. We don't need everything
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* and we use xenbus_comms for communication.
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*
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* Copyright (C) 2005 Rusty Russell, IBM Corporation
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation; or, when distributed
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* separately from the Linux kernel or incorporated into other
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* software packages, subject to the following license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include <linux/unistd.h>
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/uio.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/fcntl.h>
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#include <linux/kthread.h>
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#include <linux/rwsem.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <asm/xen/hypervisor.h>
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#include <xen/xenbus.h>
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#include <xen/xen.h>
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#include "xenbus_comms.h"
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struct xs_stored_msg {
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struct list_head list;
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struct xsd_sockmsg hdr;
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union {
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/* Queued replies. */
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struct {
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char *body;
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} reply;
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/* Queued watch events. */
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struct {
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struct xenbus_watch *handle;
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char **vec;
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unsigned int vec_size;
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} watch;
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} u;
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};
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struct xs_handle {
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/* A list of replies. Currently only one will ever be outstanding. */
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struct list_head reply_list;
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spinlock_t reply_lock;
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wait_queue_head_t reply_waitq;
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/*
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* Mutex ordering: transaction_mutex -> watch_mutex -> request_mutex.
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* response_mutex is never taken simultaneously with the other three.
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*
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* transaction_mutex must be held before incrementing
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* transaction_count. The mutex is held when a suspend is in
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* progress to prevent new transactions starting.
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*
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* When decrementing transaction_count to zero the wait queue
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* should be woken up, the suspend code waits for count to
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* reach zero.
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*/
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/* One request at a time. */
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struct mutex request_mutex;
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/* Protect xenbus reader thread against save/restore. */
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struct mutex response_mutex;
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/* Protect transactions against save/restore. */
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struct mutex transaction_mutex;
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atomic_t transaction_count;
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wait_queue_head_t transaction_wq;
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/* Protect watch (de)register against save/restore. */
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struct rw_semaphore watch_mutex;
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};
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static struct xs_handle xs_state;
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/* List of registered watches, and a lock to protect it. */
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static LIST_HEAD(watches);
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static DEFINE_SPINLOCK(watches_lock);
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/* List of pending watch callback events, and a lock to protect it. */
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static LIST_HEAD(watch_events);
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static DEFINE_SPINLOCK(watch_events_lock);
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/*
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* Details of the xenwatch callback kernel thread. The thread waits on the
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* watch_events_waitq for work to do (queued on watch_events list). When it
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* wakes up it acquires the xenwatch_mutex before reading the list and
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* carrying out work.
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*/
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static pid_t xenwatch_pid;
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static DEFINE_MUTEX(xenwatch_mutex);
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static DECLARE_WAIT_QUEUE_HEAD(watch_events_waitq);
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static int get_error(const char *errorstring)
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{
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unsigned int i;
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for (i = 0; strcmp(errorstring, xsd_errors[i].errstring) != 0; i++) {
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if (i == ARRAY_SIZE(xsd_errors) - 1) {
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printk(KERN_WARNING
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"XENBUS xen store gave: unknown error %s",
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errorstring);
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return EINVAL;
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}
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}
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return xsd_errors[i].errnum;
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}
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static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len)
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{
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struct xs_stored_msg *msg;
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char *body;
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spin_lock(&xs_state.reply_lock);
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while (list_empty(&xs_state.reply_list)) {
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spin_unlock(&xs_state.reply_lock);
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/* XXX FIXME: Avoid synchronous wait for response here. */
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wait_event(xs_state.reply_waitq,
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!list_empty(&xs_state.reply_list));
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spin_lock(&xs_state.reply_lock);
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}
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msg = list_entry(xs_state.reply_list.next,
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struct xs_stored_msg, list);
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list_del(&msg->list);
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spin_unlock(&xs_state.reply_lock);
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*type = msg->hdr.type;
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if (len)
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*len = msg->hdr.len;
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body = msg->u.reply.body;
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kfree(msg);
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return body;
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}
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static void transaction_start(void)
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{
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mutex_lock(&xs_state.transaction_mutex);
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atomic_inc(&xs_state.transaction_count);
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mutex_unlock(&xs_state.transaction_mutex);
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}
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static void transaction_end(void)
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{
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if (atomic_dec_and_test(&xs_state.transaction_count))
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wake_up(&xs_state.transaction_wq);
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}
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static void transaction_suspend(void)
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{
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mutex_lock(&xs_state.transaction_mutex);
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wait_event(xs_state.transaction_wq,
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atomic_read(&xs_state.transaction_count) == 0);
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}
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static void transaction_resume(void)
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{
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mutex_unlock(&xs_state.transaction_mutex);
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}
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void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg)
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{
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void *ret;
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struct xsd_sockmsg req_msg = *msg;
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int err;
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if (req_msg.type == XS_TRANSACTION_START)
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transaction_start();
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mutex_lock(&xs_state.request_mutex);
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err = xb_write(msg, sizeof(*msg) + msg->len);
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if (err) {
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msg->type = XS_ERROR;
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ret = ERR_PTR(err);
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} else
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ret = read_reply(&msg->type, &msg->len);
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mutex_unlock(&xs_state.request_mutex);
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if ((msg->type == XS_TRANSACTION_END) ||
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((req_msg.type == XS_TRANSACTION_START) &&
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(msg->type == XS_ERROR)))
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transaction_end();
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return ret;
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}
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EXPORT_SYMBOL(xenbus_dev_request_and_reply);
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/* Send message to xs, get kmalloc'ed reply. ERR_PTR() on error. */
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static void *xs_talkv(struct xenbus_transaction t,
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enum xsd_sockmsg_type type,
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const struct kvec *iovec,
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unsigned int num_vecs,
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unsigned int *len)
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{
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struct xsd_sockmsg msg;
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void *ret = NULL;
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unsigned int i;
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int err;
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msg.tx_id = t.id;
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msg.req_id = 0;
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msg.type = type;
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msg.len = 0;
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for (i = 0; i < num_vecs; i++)
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msg.len += iovec[i].iov_len;
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mutex_lock(&xs_state.request_mutex);
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err = xb_write(&msg, sizeof(msg));
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if (err) {
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mutex_unlock(&xs_state.request_mutex);
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return ERR_PTR(err);
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}
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for (i = 0; i < num_vecs; i++) {
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err = xb_write(iovec[i].iov_base, iovec[i].iov_len);
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if (err) {
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mutex_unlock(&xs_state.request_mutex);
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return ERR_PTR(err);
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}
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}
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ret = read_reply(&msg.type, len);
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mutex_unlock(&xs_state.request_mutex);
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if (IS_ERR(ret))
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return ret;
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if (msg.type == XS_ERROR) {
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err = get_error(ret);
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kfree(ret);
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return ERR_PTR(-err);
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}
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if (msg.type != type) {
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if (printk_ratelimit())
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printk(KERN_WARNING
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"XENBUS unexpected type [%d], expected [%d]\n",
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msg.type, type);
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kfree(ret);
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return ERR_PTR(-EINVAL);
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}
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return ret;
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}
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/* Simplified version of xs_talkv: single message. */
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static void *xs_single(struct xenbus_transaction t,
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enum xsd_sockmsg_type type,
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const char *string,
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unsigned int *len)
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{
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struct kvec iovec;
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iovec.iov_base = (void *)string;
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iovec.iov_len = strlen(string) + 1;
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return xs_talkv(t, type, &iovec, 1, len);
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}
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/* Many commands only need an ack, don't care what it says. */
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static int xs_error(char *reply)
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{
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if (IS_ERR(reply))
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return PTR_ERR(reply);
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kfree(reply);
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return 0;
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}
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static unsigned int count_strings(const char *strings, unsigned int len)
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{
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unsigned int num;
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const char *p;
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for (p = strings, num = 0; p < strings + len; p += strlen(p) + 1)
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num++;
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return num;
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}
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/* Return the path to dir with /name appended. Buffer must be kfree()'ed. */
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static char *join(const char *dir, const char *name)
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{
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char *buffer;
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if (strlen(name) == 0)
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buffer = kasprintf(GFP_NOIO | __GFP_HIGH, "%s", dir);
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else
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buffer = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/%s", dir, name);
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return (!buffer) ? ERR_PTR(-ENOMEM) : buffer;
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}
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static char **split(char *strings, unsigned int len, unsigned int *num)
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{
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char *p, **ret;
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/* Count the strings. */
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*num = count_strings(strings, len);
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/* Transfer to one big alloc for easy freeing. */
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ret = kmalloc(*num * sizeof(char *) + len, GFP_NOIO | __GFP_HIGH);
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if (!ret) {
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kfree(strings);
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return ERR_PTR(-ENOMEM);
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}
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memcpy(&ret[*num], strings, len);
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kfree(strings);
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strings = (char *)&ret[*num];
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for (p = strings, *num = 0; p < strings + len; p += strlen(p) + 1)
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ret[(*num)++] = p;
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return ret;
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}
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char **xenbus_directory(struct xenbus_transaction t,
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const char *dir, const char *node, unsigned int *num)
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{
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char *strings, *path;
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unsigned int len;
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path = join(dir, node);
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if (IS_ERR(path))
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return (char **)path;
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strings = xs_single(t, XS_DIRECTORY, path, &len);
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kfree(path);
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if (IS_ERR(strings))
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return (char **)strings;
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return split(strings, len, num);
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}
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EXPORT_SYMBOL_GPL(xenbus_directory);
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/* Check if a path exists. Return 1 if it does. */
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int xenbus_exists(struct xenbus_transaction t,
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const char *dir, const char *node)
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{
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char **d;
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int dir_n;
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d = xenbus_directory(t, dir, node, &dir_n);
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if (IS_ERR(d))
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return 0;
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kfree(d);
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return 1;
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}
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EXPORT_SYMBOL_GPL(xenbus_exists);
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/* Get the value of a single file.
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* Returns a kmalloced value: call free() on it after use.
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* len indicates length in bytes.
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*/
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void *xenbus_read(struct xenbus_transaction t,
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const char *dir, const char *node, unsigned int *len)
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{
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char *path;
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void *ret;
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path = join(dir, node);
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if (IS_ERR(path))
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return (void *)path;
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ret = xs_single(t, XS_READ, path, len);
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kfree(path);
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return ret;
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}
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EXPORT_SYMBOL_GPL(xenbus_read);
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/* Write the value of a single file.
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* Returns -err on failure.
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*/
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int xenbus_write(struct xenbus_transaction t,
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const char *dir, const char *node, const char *string)
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{
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const char *path;
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struct kvec iovec[2];
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int ret;
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path = join(dir, node);
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if (IS_ERR(path))
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return PTR_ERR(path);
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iovec[0].iov_base = (void *)path;
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iovec[0].iov_len = strlen(path) + 1;
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iovec[1].iov_base = (void *)string;
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iovec[1].iov_len = strlen(string);
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ret = xs_error(xs_talkv(t, XS_WRITE, iovec, ARRAY_SIZE(iovec), NULL));
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kfree(path);
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return ret;
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}
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EXPORT_SYMBOL_GPL(xenbus_write);
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/* Create a new directory. */
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int xenbus_mkdir(struct xenbus_transaction t,
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const char *dir, const char *node)
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{
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char *path;
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int ret;
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path = join(dir, node);
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if (IS_ERR(path))
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return PTR_ERR(path);
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ret = xs_error(xs_single(t, XS_MKDIR, path, NULL));
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kfree(path);
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return ret;
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}
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EXPORT_SYMBOL_GPL(xenbus_mkdir);
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/* Destroy a file or directory (directories must be empty). */
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int xenbus_rm(struct xenbus_transaction t, const char *dir, const char *node)
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{
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char *path;
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int ret;
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path = join(dir, node);
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if (IS_ERR(path))
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return PTR_ERR(path);
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ret = xs_error(xs_single(t, XS_RM, path, NULL));
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kfree(path);
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return ret;
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}
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EXPORT_SYMBOL_GPL(xenbus_rm);
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/* Start a transaction: changes by others will not be seen during this
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* transaction, and changes will not be visible to others until end.
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*/
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int xenbus_transaction_start(struct xenbus_transaction *t)
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{
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char *id_str;
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transaction_start();
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id_str = xs_single(XBT_NIL, XS_TRANSACTION_START, "", NULL);
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if (IS_ERR(id_str)) {
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transaction_end();
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return PTR_ERR(id_str);
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}
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t->id = simple_strtoul(id_str, NULL, 0);
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kfree(id_str);
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return 0;
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}
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EXPORT_SYMBOL_GPL(xenbus_transaction_start);
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/* End a transaction.
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* If abandon is true, transaction is discarded instead of committed.
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*/
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int xenbus_transaction_end(struct xenbus_transaction t, int abort)
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{
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char abortstr[2];
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int err;
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if (abort)
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strcpy(abortstr, "F");
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else
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strcpy(abortstr, "T");
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err = xs_error(xs_single(t, XS_TRANSACTION_END, abortstr, NULL));
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transaction_end();
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return err;
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}
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EXPORT_SYMBOL_GPL(xenbus_transaction_end);
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/* Single read and scanf: returns -errno or num scanned. */
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int xenbus_scanf(struct xenbus_transaction t,
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const char *dir, const char *node, const char *fmt, ...)
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{
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va_list ap;
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int ret;
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char *val;
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val = xenbus_read(t, dir, node, NULL);
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if (IS_ERR(val))
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return PTR_ERR(val);
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va_start(ap, fmt);
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ret = vsscanf(val, fmt, ap);
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va_end(ap);
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kfree(val);
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/* Distinctive errno. */
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if (ret == 0)
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return -ERANGE;
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return ret;
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}
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EXPORT_SYMBOL_GPL(xenbus_scanf);
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/* Single printf and write: returns -errno or 0. */
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int xenbus_printf(struct xenbus_transaction t,
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const char *dir, const char *node, const char *fmt, ...)
|
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{
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va_list ap;
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int ret;
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char *buf;
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|
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va_start(ap, fmt);
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buf = kvasprintf(GFP_NOIO | __GFP_HIGH, fmt, ap);
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va_end(ap);
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|
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if (!buf)
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return -ENOMEM;
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|
|
ret = xenbus_write(t, dir, node, buf);
|
|
|
|
kfree(buf);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(xenbus_printf);
|
|
|
|
/* Takes tuples of names, scanf-style args, and void **, NULL terminated. */
|
|
int xenbus_gather(struct xenbus_transaction t, const char *dir, ...)
|
|
{
|
|
va_list ap;
|
|
const char *name;
|
|
int ret = 0;
|
|
|
|
va_start(ap, dir);
|
|
while (ret == 0 && (name = va_arg(ap, char *)) != NULL) {
|
|
const char *fmt = va_arg(ap, char *);
|
|
void *result = va_arg(ap, void *);
|
|
char *p;
|
|
|
|
p = xenbus_read(t, dir, name, NULL);
|
|
if (IS_ERR(p)) {
|
|
ret = PTR_ERR(p);
|
|
break;
|
|
}
|
|
if (fmt) {
|
|
if (sscanf(p, fmt, result) == 0)
|
|
ret = -EINVAL;
|
|
kfree(p);
|
|
} else
|
|
*(char **)result = p;
|
|
}
|
|
va_end(ap);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(xenbus_gather);
|
|
|
|
static int xs_watch(const char *path, const char *token)
|
|
{
|
|
struct kvec iov[2];
|
|
|
|
iov[0].iov_base = (void *)path;
|
|
iov[0].iov_len = strlen(path) + 1;
|
|
iov[1].iov_base = (void *)token;
|
|
iov[1].iov_len = strlen(token) + 1;
|
|
|
|
return xs_error(xs_talkv(XBT_NIL, XS_WATCH, iov,
|
|
ARRAY_SIZE(iov), NULL));
|
|
}
|
|
|
|
static int xs_unwatch(const char *path, const char *token)
|
|
{
|
|
struct kvec iov[2];
|
|
|
|
iov[0].iov_base = (char *)path;
|
|
iov[0].iov_len = strlen(path) + 1;
|
|
iov[1].iov_base = (char *)token;
|
|
iov[1].iov_len = strlen(token) + 1;
|
|
|
|
return xs_error(xs_talkv(XBT_NIL, XS_UNWATCH, iov,
|
|
ARRAY_SIZE(iov), NULL));
|
|
}
|
|
|
|
static struct xenbus_watch *find_watch(const char *token)
|
|
{
|
|
struct xenbus_watch *i, *cmp;
|
|
|
|
cmp = (void *)simple_strtoul(token, NULL, 16);
|
|
|
|
list_for_each_entry(i, &watches, list)
|
|
if (i == cmp)
|
|
return i;
|
|
|
|
return NULL;
|
|
}
|
|
/*
|
|
* Certain older XenBus toolstack cannot handle reading values that are
|
|
* not populated. Some Xen 3.4 installation are incapable of doing this
|
|
* so if we are running on anything older than 4 do not attempt to read
|
|
* control/platform-feature-xs_reset_watches.
|
|
*/
|
|
static bool xen_strict_xenbus_quirk(void)
|
|
{
|
|
#ifdef CONFIG_X86
|
|
uint32_t eax, ebx, ecx, edx, base;
|
|
|
|
base = xen_cpuid_base();
|
|
cpuid(base + 1, &eax, &ebx, &ecx, &edx);
|
|
|
|
if ((eax >> 16) < 4)
|
|
return true;
|
|
#endif
|
|
return false;
|
|
|
|
}
|
|
static void xs_reset_watches(void)
|
|
{
|
|
int err, supported = 0;
|
|
|
|
if (!xen_hvm_domain() || xen_initial_domain())
|
|
return;
|
|
|
|
if (xen_strict_xenbus_quirk())
|
|
return;
|
|
|
|
err = xenbus_scanf(XBT_NIL, "control",
|
|
"platform-feature-xs_reset_watches", "%d", &supported);
|
|
if (err != 1 || !supported)
|
|
return;
|
|
|
|
err = xs_error(xs_single(XBT_NIL, XS_RESET_WATCHES, "", NULL));
|
|
if (err && err != -EEXIST)
|
|
printk(KERN_WARNING "xs_reset_watches failed: %d\n", err);
|
|
}
|
|
|
|
/* Register callback to watch this node. */
|
|
int register_xenbus_watch(struct xenbus_watch *watch)
|
|
{
|
|
/* Pointer in ascii is the token. */
|
|
char token[sizeof(watch) * 2 + 1];
|
|
int err;
|
|
|
|
sprintf(token, "%lX", (long)watch);
|
|
|
|
down_read(&xs_state.watch_mutex);
|
|
|
|
spin_lock(&watches_lock);
|
|
BUG_ON(find_watch(token));
|
|
list_add(&watch->list, &watches);
|
|
spin_unlock(&watches_lock);
|
|
|
|
err = xs_watch(watch->node, token);
|
|
|
|
if (err) {
|
|
spin_lock(&watches_lock);
|
|
list_del(&watch->list);
|
|
spin_unlock(&watches_lock);
|
|
}
|
|
|
|
up_read(&xs_state.watch_mutex);
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(register_xenbus_watch);
|
|
|
|
void unregister_xenbus_watch(struct xenbus_watch *watch)
|
|
{
|
|
struct xs_stored_msg *msg, *tmp;
|
|
char token[sizeof(watch) * 2 + 1];
|
|
int err;
|
|
|
|
sprintf(token, "%lX", (long)watch);
|
|
|
|
down_read(&xs_state.watch_mutex);
|
|
|
|
spin_lock(&watches_lock);
|
|
BUG_ON(!find_watch(token));
|
|
list_del(&watch->list);
|
|
spin_unlock(&watches_lock);
|
|
|
|
err = xs_unwatch(watch->node, token);
|
|
if (err)
|
|
printk(KERN_WARNING
|
|
"XENBUS Failed to release watch %s: %i\n",
|
|
watch->node, err);
|
|
|
|
up_read(&xs_state.watch_mutex);
|
|
|
|
/* Make sure there are no callbacks running currently (unless
|
|
its us) */
|
|
if (current->pid != xenwatch_pid)
|
|
mutex_lock(&xenwatch_mutex);
|
|
|
|
/* Cancel pending watch events. */
|
|
spin_lock(&watch_events_lock);
|
|
list_for_each_entry_safe(msg, tmp, &watch_events, list) {
|
|
if (msg->u.watch.handle != watch)
|
|
continue;
|
|
list_del(&msg->list);
|
|
kfree(msg->u.watch.vec);
|
|
kfree(msg);
|
|
}
|
|
spin_unlock(&watch_events_lock);
|
|
|
|
if (current->pid != xenwatch_pid)
|
|
mutex_unlock(&xenwatch_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(unregister_xenbus_watch);
|
|
|
|
void xs_suspend(void)
|
|
{
|
|
transaction_suspend();
|
|
down_write(&xs_state.watch_mutex);
|
|
mutex_lock(&xs_state.request_mutex);
|
|
mutex_lock(&xs_state.response_mutex);
|
|
}
|
|
|
|
void xs_resume(void)
|
|
{
|
|
struct xenbus_watch *watch;
|
|
char token[sizeof(watch) * 2 + 1];
|
|
|
|
xb_init_comms();
|
|
|
|
mutex_unlock(&xs_state.response_mutex);
|
|
mutex_unlock(&xs_state.request_mutex);
|
|
transaction_resume();
|
|
|
|
/* No need for watches_lock: the watch_mutex is sufficient. */
|
|
list_for_each_entry(watch, &watches, list) {
|
|
sprintf(token, "%lX", (long)watch);
|
|
xs_watch(watch->node, token);
|
|
}
|
|
|
|
up_write(&xs_state.watch_mutex);
|
|
}
|
|
|
|
void xs_suspend_cancel(void)
|
|
{
|
|
mutex_unlock(&xs_state.response_mutex);
|
|
mutex_unlock(&xs_state.request_mutex);
|
|
up_write(&xs_state.watch_mutex);
|
|
mutex_unlock(&xs_state.transaction_mutex);
|
|
}
|
|
|
|
static int xenwatch_thread(void *unused)
|
|
{
|
|
struct list_head *ent;
|
|
struct xs_stored_msg *msg;
|
|
|
|
for (;;) {
|
|
wait_event_interruptible(watch_events_waitq,
|
|
!list_empty(&watch_events));
|
|
|
|
if (kthread_should_stop())
|
|
break;
|
|
|
|
mutex_lock(&xenwatch_mutex);
|
|
|
|
spin_lock(&watch_events_lock);
|
|
ent = watch_events.next;
|
|
if (ent != &watch_events)
|
|
list_del(ent);
|
|
spin_unlock(&watch_events_lock);
|
|
|
|
if (ent != &watch_events) {
|
|
msg = list_entry(ent, struct xs_stored_msg, list);
|
|
msg->u.watch.handle->callback(
|
|
msg->u.watch.handle,
|
|
(const char **)msg->u.watch.vec,
|
|
msg->u.watch.vec_size);
|
|
kfree(msg->u.watch.vec);
|
|
kfree(msg);
|
|
}
|
|
|
|
mutex_unlock(&xenwatch_mutex);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int process_msg(void)
|
|
{
|
|
struct xs_stored_msg *msg;
|
|
char *body;
|
|
int err;
|
|
|
|
/*
|
|
* We must disallow save/restore while reading a xenstore message.
|
|
* A partial read across s/r leaves us out of sync with xenstored.
|
|
*/
|
|
for (;;) {
|
|
err = xb_wait_for_data_to_read();
|
|
if (err)
|
|
return err;
|
|
mutex_lock(&xs_state.response_mutex);
|
|
if (xb_data_to_read())
|
|
break;
|
|
/* We raced with save/restore: pending data 'disappeared'. */
|
|
mutex_unlock(&xs_state.response_mutex);
|
|
}
|
|
|
|
|
|
msg = kmalloc(sizeof(*msg), GFP_NOIO | __GFP_HIGH);
|
|
if (msg == NULL) {
|
|
err = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
err = xb_read(&msg->hdr, sizeof(msg->hdr));
|
|
if (err) {
|
|
kfree(msg);
|
|
goto out;
|
|
}
|
|
|
|
if (msg->hdr.len > XENSTORE_PAYLOAD_MAX) {
|
|
kfree(msg);
|
|
err = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
body = kmalloc(msg->hdr.len + 1, GFP_NOIO | __GFP_HIGH);
|
|
if (body == NULL) {
|
|
kfree(msg);
|
|
err = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
err = xb_read(body, msg->hdr.len);
|
|
if (err) {
|
|
kfree(body);
|
|
kfree(msg);
|
|
goto out;
|
|
}
|
|
body[msg->hdr.len] = '\0';
|
|
|
|
if (msg->hdr.type == XS_WATCH_EVENT) {
|
|
msg->u.watch.vec = split(body, msg->hdr.len,
|
|
&msg->u.watch.vec_size);
|
|
if (IS_ERR(msg->u.watch.vec)) {
|
|
err = PTR_ERR(msg->u.watch.vec);
|
|
kfree(msg);
|
|
goto out;
|
|
}
|
|
|
|
spin_lock(&watches_lock);
|
|
msg->u.watch.handle = find_watch(
|
|
msg->u.watch.vec[XS_WATCH_TOKEN]);
|
|
if (msg->u.watch.handle != NULL) {
|
|
spin_lock(&watch_events_lock);
|
|
list_add_tail(&msg->list, &watch_events);
|
|
wake_up(&watch_events_waitq);
|
|
spin_unlock(&watch_events_lock);
|
|
} else {
|
|
kfree(msg->u.watch.vec);
|
|
kfree(msg);
|
|
}
|
|
spin_unlock(&watches_lock);
|
|
} else {
|
|
msg->u.reply.body = body;
|
|
spin_lock(&xs_state.reply_lock);
|
|
list_add_tail(&msg->list, &xs_state.reply_list);
|
|
spin_unlock(&xs_state.reply_lock);
|
|
wake_up(&xs_state.reply_waitq);
|
|
}
|
|
|
|
out:
|
|
mutex_unlock(&xs_state.response_mutex);
|
|
return err;
|
|
}
|
|
|
|
static int xenbus_thread(void *unused)
|
|
{
|
|
int err;
|
|
|
|
for (;;) {
|
|
err = process_msg();
|
|
if (err)
|
|
printk(KERN_WARNING "XENBUS error %d while reading "
|
|
"message\n", err);
|
|
if (kthread_should_stop())
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int xs_init(void)
|
|
{
|
|
int err;
|
|
struct task_struct *task;
|
|
|
|
INIT_LIST_HEAD(&xs_state.reply_list);
|
|
spin_lock_init(&xs_state.reply_lock);
|
|
init_waitqueue_head(&xs_state.reply_waitq);
|
|
|
|
mutex_init(&xs_state.request_mutex);
|
|
mutex_init(&xs_state.response_mutex);
|
|
mutex_init(&xs_state.transaction_mutex);
|
|
init_rwsem(&xs_state.watch_mutex);
|
|
atomic_set(&xs_state.transaction_count, 0);
|
|
init_waitqueue_head(&xs_state.transaction_wq);
|
|
|
|
/* Initialize the shared memory rings to talk to xenstored */
|
|
err = xb_init_comms();
|
|
if (err)
|
|
return err;
|
|
|
|
task = kthread_run(xenwatch_thread, NULL, "xenwatch");
|
|
if (IS_ERR(task))
|
|
return PTR_ERR(task);
|
|
xenwatch_pid = task->pid;
|
|
|
|
task = kthread_run(xenbus_thread, NULL, "xenbus");
|
|
if (IS_ERR(task))
|
|
return PTR_ERR(task);
|
|
|
|
/* shutdown watches for kexec boot */
|
|
xs_reset_watches();
|
|
|
|
return 0;
|
|
}
|