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![Simon Gaiser](/assets/img/avatar_default.png)
Users of the xenbus functions should never close a non existent transaction (for example by trying to closing the same transaction twice) but better catch it in xs_request_exit() than to corrupt the reference counter. Signed-off-by: Simon Gaiser <simon@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
940 lines
21 KiB
C
940 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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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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/reboot.h>
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#include <linux/rwsem.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.h"
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/*
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* Framework to protect suspend/resume handling against normal Xenstore
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* message handling:
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* During suspend/resume there must be no open transaction and no pending
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* Xenstore request.
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* New watch events happening in this time can be ignored by firing all watches
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* after resume.
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*/
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/* Lock protecting enter/exit critical region. */
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static DEFINE_SPINLOCK(xs_state_lock);
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/* Number of users in critical region (protected by xs_state_lock). */
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static unsigned int xs_state_users;
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/* Suspend handler waiting or already active (protected by xs_state_lock)? */
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static int xs_suspend_active;
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/* Unique Xenstore request id (protected by xs_state_lock). */
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static uint32_t xs_request_id;
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/* Wait queue for all callers waiting for critical region to become usable. */
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static DECLARE_WAIT_QUEUE_HEAD(xs_state_enter_wq);
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/* Wait queue for suspend handling waiting for critical region being empty. */
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static DECLARE_WAIT_QUEUE_HEAD(xs_state_exit_wq);
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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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/* Protect watch (de)register against save/restore. */
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static DECLARE_RWSEM(xs_watch_rwsem);
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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 void xs_suspend_enter(void)
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{
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spin_lock(&xs_state_lock);
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xs_suspend_active++;
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spin_unlock(&xs_state_lock);
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wait_event(xs_state_exit_wq, xs_state_users == 0);
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}
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static void xs_suspend_exit(void)
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{
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spin_lock(&xs_state_lock);
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xs_suspend_active--;
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spin_unlock(&xs_state_lock);
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wake_up_all(&xs_state_enter_wq);
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}
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static uint32_t xs_request_enter(struct xb_req_data *req)
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{
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uint32_t rq_id;
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req->type = req->msg.type;
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spin_lock(&xs_state_lock);
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while (!xs_state_users && xs_suspend_active) {
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spin_unlock(&xs_state_lock);
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wait_event(xs_state_enter_wq, xs_suspend_active == 0);
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spin_lock(&xs_state_lock);
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}
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if (req->type == XS_TRANSACTION_START)
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xs_state_users++;
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xs_state_users++;
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rq_id = xs_request_id++;
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spin_unlock(&xs_state_lock);
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return rq_id;
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}
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void xs_request_exit(struct xb_req_data *req)
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{
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spin_lock(&xs_state_lock);
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xs_state_users--;
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if ((req->type == XS_TRANSACTION_START && req->msg.type == XS_ERROR) ||
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(req->type == XS_TRANSACTION_END &&
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!WARN_ON_ONCE(req->msg.type == XS_ERROR &&
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!strcmp(req->body, "ENOENT"))))
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xs_state_users--;
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spin_unlock(&xs_state_lock);
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if (xs_suspend_active && !xs_state_users)
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wake_up(&xs_state_exit_wq);
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}
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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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pr_warn("xen store gave: unknown error %s\n",
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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 bool xenbus_ok(void)
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{
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switch (xen_store_domain_type) {
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case XS_LOCAL:
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switch (system_state) {
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case SYSTEM_POWER_OFF:
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case SYSTEM_RESTART:
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case SYSTEM_HALT:
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return false;
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default:
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break;
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}
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return true;
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case XS_PV:
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case XS_HVM:
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/* FIXME: Could check that the remote domain is alive,
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* but it is normally initial domain. */
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return true;
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default:
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break;
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}
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return false;
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}
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static bool test_reply(struct xb_req_data *req)
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{
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if (req->state == xb_req_state_got_reply || !xenbus_ok())
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return true;
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/* Make sure to reread req->state each time. */
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barrier();
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return false;
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}
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static void *read_reply(struct xb_req_data *req)
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{
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while (req->state != xb_req_state_got_reply) {
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wait_event(req->wq, test_reply(req));
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if (!xenbus_ok())
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/*
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* If we are in the process of being shut-down there is
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* no point of trying to contact XenBus - it is either
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* killed (xenstored application) or the other domain
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* has been killed or is unreachable.
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*/
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return ERR_PTR(-EIO);
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if (req->err)
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return ERR_PTR(req->err);
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}
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return req->body;
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}
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static void xs_send(struct xb_req_data *req, struct xsd_sockmsg *msg)
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{
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bool notify;
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req->msg = *msg;
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req->err = 0;
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req->state = xb_req_state_queued;
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init_waitqueue_head(&req->wq);
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/* Save the caller req_id and restore it later in the reply */
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req->caller_req_id = req->msg.req_id;
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req->msg.req_id = xs_request_enter(req);
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mutex_lock(&xb_write_mutex);
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list_add_tail(&req->list, &xb_write_list);
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notify = list_is_singular(&xb_write_list);
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mutex_unlock(&xb_write_mutex);
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if (notify)
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wake_up(&xb_waitq);
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}
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static void *xs_wait_for_reply(struct xb_req_data *req, struct xsd_sockmsg *msg)
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{
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void *ret;
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ret = read_reply(req);
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xs_request_exit(req);
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msg->type = req->msg.type;
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msg->len = req->msg.len;
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mutex_lock(&xb_write_mutex);
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if (req->state == xb_req_state_queued ||
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req->state == xb_req_state_wait_reply)
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req->state = xb_req_state_aborted;
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else
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kfree(req);
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mutex_unlock(&xb_write_mutex);
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return ret;
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}
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static void xs_wake_up(struct xb_req_data *req)
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{
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wake_up(&req->wq);
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}
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int xenbus_dev_request_and_reply(struct xsd_sockmsg *msg, void *par)
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{
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struct xb_req_data *req;
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struct kvec *vec;
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req = kmalloc(sizeof(*req) + sizeof(*vec), GFP_KERNEL);
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if (!req)
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return -ENOMEM;
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vec = (struct kvec *)(req + 1);
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vec->iov_len = msg->len;
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vec->iov_base = msg + 1;
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req->vec = vec;
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req->num_vecs = 1;
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req->cb = xenbus_dev_queue_reply;
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req->par = par;
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xs_send(req, msg);
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return 0;
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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 xb_req_data *req;
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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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req = kmalloc(sizeof(*req), GFP_NOIO | __GFP_HIGH);
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if (!req)
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return ERR_PTR(-ENOMEM);
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req->vec = iovec;
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req->num_vecs = num_vecs;
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req->cb = xs_wake_up;
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msg.req_id = 0;
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msg.tx_id = t.id;
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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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xs_send(req, &msg);
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ret = xs_wait_for_reply(req, &msg);
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if (len)
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*len = msg.len;
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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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pr_warn_ratelimited("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);
|
|
|
|
/* Start a transaction: changes by others will not be seen during this
|
|
* transaction, and changes will not be visible to others until end.
|
|
*/
|
|
int xenbus_transaction_start(struct xenbus_transaction *t)
|
|
{
|
|
char *id_str;
|
|
|
|
id_str = xs_single(XBT_NIL, XS_TRANSACTION_START, "", NULL);
|
|
if (IS_ERR(id_str))
|
|
return PTR_ERR(id_str);
|
|
|
|
t->id = simple_strtoul(id_str, NULL, 0);
|
|
kfree(id_str);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(xenbus_transaction_start);
|
|
|
|
/* End a transaction.
|
|
* If abandon is true, transaction is discarded instead of committed.
|
|
*/
|
|
int xenbus_transaction_end(struct xenbus_transaction t, int abort)
|
|
{
|
|
char abortstr[2];
|
|
|
|
if (abort)
|
|
strcpy(abortstr, "F");
|
|
else
|
|
strcpy(abortstr, "T");
|
|
|
|
return xs_error(xs_single(t, XS_TRANSACTION_END, abortstr, NULL));
|
|
}
|
|
EXPORT_SYMBOL_GPL(xenbus_transaction_end);
|
|
|
|
/* Single read and scanf: returns -errno or num scanned. */
|
|
int xenbus_scanf(struct xenbus_transaction t,
|
|
const char *dir, const char *node, const char *fmt, ...)
|
|
{
|
|
va_list ap;
|
|
int ret;
|
|
char *val;
|
|
|
|
val = xenbus_read(t, dir, node, NULL);
|
|
if (IS_ERR(val))
|
|
return PTR_ERR(val);
|
|
|
|
va_start(ap, fmt);
|
|
ret = vsscanf(val, fmt, ap);
|
|
va_end(ap);
|
|
kfree(val);
|
|
/* Distinctive errno. */
|
|
if (ret == 0)
|
|
return -ERANGE;
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(xenbus_scanf);
|
|
|
|
/* Read an (optional) unsigned value. */
|
|
unsigned int xenbus_read_unsigned(const char *dir, const char *node,
|
|
unsigned int default_val)
|
|
{
|
|
unsigned int val;
|
|
int ret;
|
|
|
|
ret = xenbus_scanf(XBT_NIL, dir, node, "%u", &val);
|
|
if (ret <= 0)
|
|
val = default_val;
|
|
|
|
return val;
|
|
}
|
|
EXPORT_SYMBOL_GPL(xenbus_read_unsigned);
|
|
|
|
/* Single printf and write: returns -errno or 0. */
|
|
int xenbus_printf(struct xenbus_transaction t,
|
|
const char *dir, const char *node, const char *fmt, ...)
|
|
{
|
|
va_list ap;
|
|
int ret;
|
|
char *buf;
|
|
|
|
va_start(ap, fmt);
|
|
buf = kvasprintf(GFP_NOIO | __GFP_HIGH, fmt, ap);
|
|
va_end(ap);
|
|
|
|
if (!buf)
|
|
return -ENOMEM;
|
|
|
|
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;
|
|
}
|
|
|
|
int xs_watch_msg(struct xs_watch_event *event)
|
|
{
|
|
if (count_strings(event->body, event->len) != 2) {
|
|
kfree(event);
|
|
return -EINVAL;
|
|
}
|
|
event->path = (const char *)event->body;
|
|
event->token = (const char *)strchr(event->body, '\0') + 1;
|
|
|
|
spin_lock(&watches_lock);
|
|
event->handle = find_watch(event->token);
|
|
if (event->handle != NULL) {
|
|
spin_lock(&watch_events_lock);
|
|
list_add_tail(&event->list, &watch_events);
|
|
wake_up(&watch_events_waitq);
|
|
spin_unlock(&watch_events_lock);
|
|
} else
|
|
kfree(event);
|
|
spin_unlock(&watches_lock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
|
|
if (!xen_hvm_domain() || xen_initial_domain())
|
|
return;
|
|
|
|
if (xen_strict_xenbus_quirk())
|
|
return;
|
|
|
|
if (!xenbus_read_unsigned("control",
|
|
"platform-feature-xs_reset_watches", 0))
|
|
return;
|
|
|
|
err = xs_error(xs_single(XBT_NIL, XS_RESET_WATCHES, "", NULL));
|
|
if (err && err != -EEXIST)
|
|
pr_warn("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_watch_rwsem);
|
|
|
|
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_watch_rwsem);
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(register_xenbus_watch);
|
|
|
|
void unregister_xenbus_watch(struct xenbus_watch *watch)
|
|
{
|
|
struct xs_watch_event *event, *tmp;
|
|
char token[sizeof(watch) * 2 + 1];
|
|
int err;
|
|
|
|
sprintf(token, "%lX", (long)watch);
|
|
|
|
down_read(&xs_watch_rwsem);
|
|
|
|
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)
|
|
pr_warn("Failed to release watch %s: %i\n", watch->node, err);
|
|
|
|
up_read(&xs_watch_rwsem);
|
|
|
|
/* 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(event, tmp, &watch_events, list) {
|
|
if (event->handle != watch)
|
|
continue;
|
|
list_del(&event->list);
|
|
kfree(event);
|
|
}
|
|
spin_unlock(&watch_events_lock);
|
|
|
|
if (current->pid != xenwatch_pid)
|
|
mutex_unlock(&xenwatch_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(unregister_xenbus_watch);
|
|
|
|
void xs_suspend(void)
|
|
{
|
|
xs_suspend_enter();
|
|
|
|
down_write(&xs_watch_rwsem);
|
|
mutex_lock(&xs_response_mutex);
|
|
}
|
|
|
|
void xs_resume(void)
|
|
{
|
|
struct xenbus_watch *watch;
|
|
char token[sizeof(watch) * 2 + 1];
|
|
|
|
xb_init_comms();
|
|
|
|
mutex_unlock(&xs_response_mutex);
|
|
|
|
xs_suspend_exit();
|
|
|
|
/* No need for watches_lock: the xs_watch_rwsem is sufficient. */
|
|
list_for_each_entry(watch, &watches, list) {
|
|
sprintf(token, "%lX", (long)watch);
|
|
xs_watch(watch->node, token);
|
|
}
|
|
|
|
up_write(&xs_watch_rwsem);
|
|
}
|
|
|
|
void xs_suspend_cancel(void)
|
|
{
|
|
mutex_unlock(&xs_response_mutex);
|
|
up_write(&xs_watch_rwsem);
|
|
|
|
xs_suspend_exit();
|
|
}
|
|
|
|
static int xenwatch_thread(void *unused)
|
|
{
|
|
struct list_head *ent;
|
|
struct xs_watch_event *event;
|
|
|
|
xenwatch_pid = current->pid;
|
|
|
|
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) {
|
|
event = list_entry(ent, struct xs_watch_event, list);
|
|
event->handle->callback(event->handle, event->path,
|
|
event->token);
|
|
kfree(event);
|
|
}
|
|
|
|
mutex_unlock(&xenwatch_mutex);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Wake up all threads waiting for a xenstore reply. In case of shutdown all
|
|
* pending replies will be marked as "aborted" in order to let the waiters
|
|
* return in spite of xenstore possibly no longer being able to reply. This
|
|
* will avoid blocking shutdown by a thread waiting for xenstore but being
|
|
* necessary for shutdown processing to proceed.
|
|
*/
|
|
static int xs_reboot_notify(struct notifier_block *nb,
|
|
unsigned long code, void *unused)
|
|
{
|
|
struct xb_req_data *req;
|
|
|
|
mutex_lock(&xb_write_mutex);
|
|
list_for_each_entry(req, &xs_reply_list, list)
|
|
wake_up(&req->wq);
|
|
list_for_each_entry(req, &xb_write_list, list)
|
|
wake_up(&req->wq);
|
|
mutex_unlock(&xb_write_mutex);
|
|
return NOTIFY_DONE;
|
|
}
|
|
|
|
static struct notifier_block xs_reboot_nb = {
|
|
.notifier_call = xs_reboot_notify,
|
|
};
|
|
|
|
int xs_init(void)
|
|
{
|
|
int err;
|
|
struct task_struct *task;
|
|
|
|
register_reboot_notifier(&xs_reboot_nb);
|
|
|
|
/* 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);
|
|
|
|
/* shutdown watches for kexec boot */
|
|
xs_reset_watches();
|
|
|
|
return 0;
|
|
}
|