diff options
Diffstat (limited to 'drivers/misc/vmw_vmci/vmci_event.c')
| -rw-r--r-- | drivers/misc/vmw_vmci/vmci_event.c | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/drivers/misc/vmw_vmci/vmci_event.c b/drivers/misc/vmw_vmci/vmci_event.c new file mode 100644 index 000000000..84258a480 --- /dev/null +++ b/drivers/misc/vmw_vmci/vmci_event.c @@ -0,0 +1,225 @@ +/* + * 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 <linux/rculist.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); |