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1d990201 GZ |
1 | /* |
2 | * VMware VMCI Driver | |
3 | * | |
4 | * Copyright (C) 2012 VMware, Inc. All rights reserved. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License as published by the | |
8 | * Free Software Foundation version 2 and no later version. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, but | |
11 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | |
12 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
13 | * for more details. | |
14 | */ | |
15 | ||
16 | #include <linux/vmw_vmci_defs.h> | |
17 | #include <linux/vmw_vmci_api.h> | |
18 | #include <linux/list.h> | |
19 | #include <linux/module.h> | |
20 | #include <linux/sched.h> | |
21 | #include <linux/slab.h> | |
22 | ||
23 | #include "vmci_driver.h" | |
24 | #include "vmci_event.h" | |
25 | ||
26 | #define EVENT_MAGIC 0xEABE0000 | |
27 | #define VMCI_EVENT_MAX_ATTEMPTS 10 | |
28 | ||
29 | struct vmci_subscription { | |
30 | u32 id; | |
31 | u32 event; | |
32 | vmci_event_cb callback; | |
33 | void *callback_data; | |
34 | struct list_head node; /* on one of subscriber lists */ | |
35 | }; | |
36 | ||
37 | static struct list_head subscriber_array[VMCI_EVENT_MAX]; | |
38 | static DEFINE_MUTEX(subscriber_mutex); | |
39 | ||
40 | int __init vmci_event_init(void) | |
41 | { | |
42 | int i; | |
43 | ||
44 | for (i = 0; i < VMCI_EVENT_MAX; i++) | |
45 | INIT_LIST_HEAD(&subscriber_array[i]); | |
46 | ||
47 | return VMCI_SUCCESS; | |
48 | } | |
49 | ||
50 | void vmci_event_exit(void) | |
51 | { | |
52 | int e; | |
53 | ||
54 | /* We free all memory at exit. */ | |
55 | for (e = 0; e < VMCI_EVENT_MAX; e++) { | |
56 | struct vmci_subscription *cur, *p2; | |
57 | list_for_each_entry_safe(cur, p2, &subscriber_array[e], node) { | |
58 | ||
59 | /* | |
60 | * We should never get here because all events | |
61 | * should have been unregistered before we try | |
62 | * to unload the driver module. | |
63 | */ | |
64 | pr_warn("Unexpected free events occurring\n"); | |
65 | list_del(&cur->node); | |
66 | kfree(cur); | |
67 | } | |
68 | } | |
69 | } | |
70 | ||
71 | /* | |
72 | * Find entry. Assumes subscriber_mutex is held. | |
73 | */ | |
74 | static struct vmci_subscription *event_find(u32 sub_id) | |
75 | { | |
76 | int e; | |
77 | ||
78 | for (e = 0; e < VMCI_EVENT_MAX; e++) { | |
79 | struct vmci_subscription *cur; | |
80 | list_for_each_entry(cur, &subscriber_array[e], node) { | |
81 | if (cur->id == sub_id) | |
82 | return cur; | |
83 | } | |
84 | } | |
85 | return NULL; | |
86 | } | |
87 | ||
88 | /* | |
89 | * Actually delivers the events to the subscribers. | |
90 | * The callback function for each subscriber is invoked. | |
91 | */ | |
92 | static void event_deliver(struct vmci_event_msg *event_msg) | |
93 | { | |
94 | struct vmci_subscription *cur; | |
95 | struct list_head *subscriber_list; | |
96 | ||
97 | rcu_read_lock(); | |
98 | subscriber_list = &subscriber_array[event_msg->event_data.event]; | |
99 | list_for_each_entry_rcu(cur, subscriber_list, node) { | |
100 | cur->callback(cur->id, &event_msg->event_data, | |
101 | cur->callback_data); | |
102 | } | |
103 | rcu_read_unlock(); | |
104 | } | |
105 | ||
106 | /* | |
107 | * Dispatcher for the VMCI_EVENT_RECEIVE datagrams. Calls all | |
108 | * subscribers for given event. | |
109 | */ | |
110 | int vmci_event_dispatch(struct vmci_datagram *msg) | |
111 | { | |
112 | struct vmci_event_msg *event_msg = (struct vmci_event_msg *)msg; | |
113 | ||
114 | if (msg->payload_size < sizeof(u32) || | |
115 | msg->payload_size > sizeof(struct vmci_event_data_max)) | |
116 | return VMCI_ERROR_INVALID_ARGS; | |
117 | ||
118 | if (!VMCI_EVENT_VALID(event_msg->event_data.event)) | |
119 | return VMCI_ERROR_EVENT_UNKNOWN; | |
120 | ||
121 | event_deliver(event_msg); | |
122 | return VMCI_SUCCESS; | |
123 | } | |
124 | ||
125 | /* | |
126 | * vmci_event_subscribe() - Subscribe to a given event. | |
127 | * @event: The event to subscribe to. | |
128 | * @callback: The callback to invoke upon the event. | |
129 | * @callback_data: Data to pass to the callback. | |
130 | * @subscription_id: ID used to track subscription. Used with | |
131 | * vmci_event_unsubscribe() | |
132 | * | |
133 | * Subscribes to the provided event. The callback specified will be | |
134 | * fired from RCU critical section and therefore must not sleep. | |
135 | */ | |
136 | int vmci_event_subscribe(u32 event, | |
137 | vmci_event_cb callback, | |
138 | void *callback_data, | |
139 | u32 *new_subscription_id) | |
140 | { | |
141 | struct vmci_subscription *sub; | |
142 | int attempts; | |
143 | int retval; | |
144 | bool have_new_id = false; | |
145 | ||
146 | if (!new_subscription_id) { | |
147 | pr_devel("%s: Invalid subscription (NULL)\n", __func__); | |
148 | return VMCI_ERROR_INVALID_ARGS; | |
149 | } | |
150 | ||
151 | if (!VMCI_EVENT_VALID(event) || !callback) { | |
152 | pr_devel("%s: Failed to subscribe to event (type=%d) (callback=%p) (data=%p)\n", | |
153 | __func__, event, callback, callback_data); | |
154 | return VMCI_ERROR_INVALID_ARGS; | |
155 | } | |
156 | ||
157 | sub = kzalloc(sizeof(*sub), GFP_KERNEL); | |
158 | if (!sub) | |
159 | return VMCI_ERROR_NO_MEM; | |
160 | ||
161 | sub->id = VMCI_EVENT_MAX; | |
162 | sub->event = event; | |
163 | sub->callback = callback; | |
164 | sub->callback_data = callback_data; | |
165 | INIT_LIST_HEAD(&sub->node); | |
166 | ||
167 | mutex_lock(&subscriber_mutex); | |
168 | ||
169 | /* Creation of a new event is always allowed. */ | |
170 | for (attempts = 0; attempts < VMCI_EVENT_MAX_ATTEMPTS; attempts++) { | |
171 | static u32 subscription_id; | |
172 | /* | |
173 | * We try to get an id a couple of time before | |
174 | * claiming we are out of resources. | |
175 | */ | |
176 | ||
177 | /* Test for duplicate id. */ | |
178 | if (!event_find(++subscription_id)) { | |
179 | sub->id = subscription_id; | |
180 | have_new_id = true; | |
181 | break; | |
182 | } | |
183 | } | |
184 | ||
185 | if (have_new_id) { | |
186 | list_add_rcu(&sub->node, &subscriber_array[event]); | |
187 | retval = VMCI_SUCCESS; | |
188 | } else { | |
189 | retval = VMCI_ERROR_NO_RESOURCES; | |
190 | } | |
191 | ||
192 | mutex_unlock(&subscriber_mutex); | |
193 | ||
194 | *new_subscription_id = sub->id; | |
195 | return retval; | |
196 | } | |
197 | EXPORT_SYMBOL_GPL(vmci_event_subscribe); | |
198 | ||
199 | /* | |
200 | * vmci_event_unsubscribe() - unsubscribe from an event. | |
201 | * @sub_id: A subscription ID as provided by vmci_event_subscribe() | |
202 | * | |
203 | * Unsubscribe from given event. Removes it from list and frees it. | |
204 | * Will return callback_data if requested by caller. | |
205 | */ | |
206 | int vmci_event_unsubscribe(u32 sub_id) | |
207 | { | |
208 | struct vmci_subscription *s; | |
209 | ||
210 | mutex_lock(&subscriber_mutex); | |
211 | s = event_find(sub_id); | |
212 | if (s) | |
213 | list_del_rcu(&s->node); | |
214 | mutex_unlock(&subscriber_mutex); | |
215 | ||
216 | if (!s) | |
217 | return VMCI_ERROR_NOT_FOUND; | |
218 | ||
219 | synchronize_rcu(); | |
220 | kfree(s); | |
221 | ||
222 | return VMCI_SUCCESS; | |
223 | } | |
224 | EXPORT_SYMBOL_GPL(vmci_event_unsubscribe); |