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956 lines
22 KiB
956 lines
22 KiB
/****************************************************************************** |
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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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/* |
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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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|
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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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|
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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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/* 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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xb_dev_generation_id++; |
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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 && !req->user_req) |
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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 && !req->user_req && |
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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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/* read req->state before all other fields */ |
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virt_rmb(); |
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return true; |
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} |
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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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do { |
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wait_event(req->wq, test_reply(req)); |
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|
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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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} while (req->state != xb_req_state_got_reply); |
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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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req->user_req = true; |
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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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req->user_req = false; |
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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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|
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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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|
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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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|
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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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return PTR_ERR(id_str); |
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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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|
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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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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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return xs_error(xs_single(t, XS_TRANSACTION_END, abortstr, NULL)); |
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} |
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EXPORT_SYMBOL_GPL(xenbus_transaction_end); |
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|
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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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|
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/* Read an (optional) unsigned value. */ |
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unsigned int xenbus_read_unsigned(const char *dir, const char *node, |
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unsigned int default_val) |
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{ |
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unsigned int val; |
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int ret; |
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|
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ret = xenbus_scanf(XBT_NIL, dir, node, "%u", &val); |
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if (ret <= 0) |
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val = default_val; |
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|
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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 && |
|
(!event->handle->will_handle || |
|
event->handle->will_handle(event->handle, |
|
event->path, event->token))) { |
|
spin_lock(&watch_events_lock); |
|
list_add_tail(&event->list, &watch_events); |
|
event->handle->nr_pending++; |
|
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); |
|
|
|
watch->nr_pending = 0; |
|
|
|
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); |
|
if (watch->nr_pending) { |
|
list_for_each_entry_safe(event, tmp, &watch_events, list) { |
|
if (event->handle != watch) |
|
continue; |
|
list_del(&event->list); |
|
kfree(event); |
|
} |
|
watch->nr_pending = 0; |
|
} |
|
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 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); |
|
event = list_first_entry_or_null(&watch_events, |
|
struct xs_watch_event, list); |
|
if (event) { |
|
list_del(&event->list); |
|
event->handle->nr_pending--; |
|
} |
|
spin_unlock(&watch_events_lock); |
|
|
|
if (event) { |
|
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; |
|
}
|
|
|