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