![Ingo Molnar](/assets/img/avatar_default.png)
We don't actually need the full rculist.h header in sched.h anymore, we will be able to include the smaller rcupdate.h header instead. But first update code that relied on the implicit header inclusion. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
226 lines
5.4 KiB
C
226 lines
5.4 KiB
C
/*
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* VMware VMCI Driver
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*
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* Copyright (C) 2012 VMware, Inc. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation version 2 and no later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include <linux/vmw_vmci_defs.h>
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#include <linux/vmw_vmci_api.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/rculist.h>
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#include "vmci_driver.h"
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#include "vmci_event.h"
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#define EVENT_MAGIC 0xEABE0000
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#define VMCI_EVENT_MAX_ATTEMPTS 10
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struct vmci_subscription {
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u32 id;
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u32 event;
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vmci_event_cb callback;
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void *callback_data;
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struct list_head node; /* on one of subscriber lists */
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};
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static struct list_head subscriber_array[VMCI_EVENT_MAX];
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static DEFINE_MUTEX(subscriber_mutex);
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int __init vmci_event_init(void)
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{
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int i;
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for (i = 0; i < VMCI_EVENT_MAX; i++)
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INIT_LIST_HEAD(&subscriber_array[i]);
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return VMCI_SUCCESS;
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}
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void vmci_event_exit(void)
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{
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int e;
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/* We free all memory at exit. */
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for (e = 0; e < VMCI_EVENT_MAX; e++) {
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struct vmci_subscription *cur, *p2;
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list_for_each_entry_safe(cur, p2, &subscriber_array[e], node) {
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/*
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* We should never get here because all events
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* should have been unregistered before we try
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* to unload the driver module.
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*/
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pr_warn("Unexpected free events occurring\n");
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list_del(&cur->node);
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kfree(cur);
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}
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}
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}
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/*
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* Find entry. Assumes subscriber_mutex is held.
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*/
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static struct vmci_subscription *event_find(u32 sub_id)
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{
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int e;
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for (e = 0; e < VMCI_EVENT_MAX; e++) {
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struct vmci_subscription *cur;
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list_for_each_entry(cur, &subscriber_array[e], node) {
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if (cur->id == sub_id)
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return cur;
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}
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}
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return NULL;
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}
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/*
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* Actually delivers the events to the subscribers.
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* The callback function for each subscriber is invoked.
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*/
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static void event_deliver(struct vmci_event_msg *event_msg)
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{
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struct vmci_subscription *cur;
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struct list_head *subscriber_list;
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rcu_read_lock();
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subscriber_list = &subscriber_array[event_msg->event_data.event];
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list_for_each_entry_rcu(cur, subscriber_list, node) {
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cur->callback(cur->id, &event_msg->event_data,
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cur->callback_data);
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}
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rcu_read_unlock();
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}
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/*
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* Dispatcher for the VMCI_EVENT_RECEIVE datagrams. Calls all
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* subscribers for given event.
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*/
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int vmci_event_dispatch(struct vmci_datagram *msg)
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{
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struct vmci_event_msg *event_msg = (struct vmci_event_msg *)msg;
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if (msg->payload_size < sizeof(u32) ||
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msg->payload_size > sizeof(struct vmci_event_data_max))
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return VMCI_ERROR_INVALID_ARGS;
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if (!VMCI_EVENT_VALID(event_msg->event_data.event))
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return VMCI_ERROR_EVENT_UNKNOWN;
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event_deliver(event_msg);
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return VMCI_SUCCESS;
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}
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/*
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* vmci_event_subscribe() - Subscribe to a given event.
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* @event: The event to subscribe to.
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* @callback: The callback to invoke upon the event.
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* @callback_data: Data to pass to the callback.
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* @subscription_id: ID used to track subscription. Used with
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* vmci_event_unsubscribe()
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*
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* Subscribes to the provided event. The callback specified will be
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* fired from RCU critical section and therefore must not sleep.
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*/
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int vmci_event_subscribe(u32 event,
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vmci_event_cb callback,
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void *callback_data,
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u32 *new_subscription_id)
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{
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struct vmci_subscription *sub;
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int attempts;
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int retval;
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bool have_new_id = false;
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if (!new_subscription_id) {
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pr_devel("%s: Invalid subscription (NULL)\n", __func__);
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return VMCI_ERROR_INVALID_ARGS;
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}
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if (!VMCI_EVENT_VALID(event) || !callback) {
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pr_devel("%s: Failed to subscribe to event (type=%d) (callback=%p) (data=%p)\n",
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__func__, event, callback, callback_data);
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return VMCI_ERROR_INVALID_ARGS;
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}
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sub = kzalloc(sizeof(*sub), GFP_KERNEL);
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if (!sub)
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return VMCI_ERROR_NO_MEM;
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sub->id = VMCI_EVENT_MAX;
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sub->event = event;
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sub->callback = callback;
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sub->callback_data = callback_data;
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INIT_LIST_HEAD(&sub->node);
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mutex_lock(&subscriber_mutex);
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/* Creation of a new event is always allowed. */
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for (attempts = 0; attempts < VMCI_EVENT_MAX_ATTEMPTS; attempts++) {
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static u32 subscription_id;
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/*
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* We try to get an id a couple of time before
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* claiming we are out of resources.
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*/
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/* Test for duplicate id. */
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if (!event_find(++subscription_id)) {
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sub->id = subscription_id;
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have_new_id = true;
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break;
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}
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}
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if (have_new_id) {
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list_add_rcu(&sub->node, &subscriber_array[event]);
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retval = VMCI_SUCCESS;
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} else {
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retval = VMCI_ERROR_NO_RESOURCES;
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}
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mutex_unlock(&subscriber_mutex);
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*new_subscription_id = sub->id;
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return retval;
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}
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EXPORT_SYMBOL_GPL(vmci_event_subscribe);
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/*
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* vmci_event_unsubscribe() - unsubscribe from an event.
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* @sub_id: A subscription ID as provided by vmci_event_subscribe()
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*
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* Unsubscribe from given event. Removes it from list and frees it.
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* Will return callback_data if requested by caller.
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*/
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int vmci_event_unsubscribe(u32 sub_id)
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{
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struct vmci_subscription *s;
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mutex_lock(&subscriber_mutex);
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s = event_find(sub_id);
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if (s)
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list_del_rcu(&s->node);
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mutex_unlock(&subscriber_mutex);
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if (!s)
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return VMCI_ERROR_NOT_FOUND;
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synchronize_rcu();
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kfree(s);
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return VMCI_SUCCESS;
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}
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EXPORT_SYMBOL_GPL(vmci_event_unsubscribe);
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