VMCI: event handling implementation.
VMCI event code that manages event handlers and handles callbacks when specific events fire. Signed-off-by: George Zhang <georgezhang@vmware.com> Acked-by: Andy king <acking@vmware.com> Acked-by: Dmitry Torokhov <dtor@vmware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
George Zhang
Greg Kroah-Hartman
parent
197dbaaabd
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1d990201f9
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/*
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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 "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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@ -0,0 +1,25 @@
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/*
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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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#ifndef __VMCI_EVENT_H__
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#define __VMCI_EVENT_H__
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#include <linux/vmw_vmci_api.h>
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int vmci_event_init(void);
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void vmci_event_exit(void);
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int vmci_event_dispatch(struct vmci_datagram *msg);
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#endif /*__VMCI_EVENT_H__ */
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