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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> | |
b2d09103 | 22 | #include <linux/rculist.h> |
1d990201 GZ |
23 | |
24 | #include "vmci_driver.h" | |
25 | #include "vmci_event.h" | |
26 | ||
27 | #define EVENT_MAGIC 0xEABE0000 | |
28 | #define VMCI_EVENT_MAX_ATTEMPTS 10 | |
29 | ||
30 | struct vmci_subscription { | |
31 | u32 id; | |
32 | u32 event; | |
33 | vmci_event_cb callback; | |
34 | void *callback_data; | |
35 | struct list_head node; /* on one of subscriber lists */ | |
36 | }; | |
37 | ||
38 | static struct list_head subscriber_array[VMCI_EVENT_MAX]; | |
39 | static DEFINE_MUTEX(subscriber_mutex); | |
40 | ||
41 | int __init vmci_event_init(void) | |
42 | { | |
43 | int i; | |
44 | ||
45 | for (i = 0; i < VMCI_EVENT_MAX; i++) | |
46 | INIT_LIST_HEAD(&subscriber_array[i]); | |
47 | ||
48 | return VMCI_SUCCESS; | |
49 | } | |
50 | ||
51 | void vmci_event_exit(void) | |
52 | { | |
53 | int e; | |
54 | ||
55 | /* We free all memory at exit. */ | |
56 | for (e = 0; e < VMCI_EVENT_MAX; e++) { | |
57 | struct vmci_subscription *cur, *p2; | |
58 | list_for_each_entry_safe(cur, p2, &subscriber_array[e], node) { | |
59 | ||
60 | /* | |
61 | * We should never get here because all events | |
62 | * should have been unregistered before we try | |
63 | * to unload the driver module. | |
64 | */ | |
65 | pr_warn("Unexpected free events occurring\n"); | |
66 | list_del(&cur->node); | |
67 | kfree(cur); | |
68 | } | |
69 | } | |
70 | } | |
71 | ||
72 | /* | |
73 | * Find entry. Assumes subscriber_mutex is held. | |
74 | */ | |
75 | static struct vmci_subscription *event_find(u32 sub_id) | |
76 | { | |
77 | int e; | |
78 | ||
79 | for (e = 0; e < VMCI_EVENT_MAX; e++) { | |
80 | struct vmci_subscription *cur; | |
81 | list_for_each_entry(cur, &subscriber_array[e], node) { | |
82 | if (cur->id == sub_id) | |
83 | return cur; | |
84 | } | |
85 | } | |
86 | return NULL; | |
87 | } | |
88 | ||
89 | /* | |
90 | * Actually delivers the events to the subscribers. | |
91 | * The callback function for each subscriber is invoked. | |
92 | */ | |
93 | static void event_deliver(struct vmci_event_msg *event_msg) | |
94 | { | |
95 | struct vmci_subscription *cur; | |
96 | struct list_head *subscriber_list; | |
97 | ||
98 | rcu_read_lock(); | |
99 | subscriber_list = &subscriber_array[event_msg->event_data.event]; | |
100 | list_for_each_entry_rcu(cur, subscriber_list, node) { | |
101 | cur->callback(cur->id, &event_msg->event_data, | |
102 | cur->callback_data); | |
103 | } | |
104 | rcu_read_unlock(); | |
105 | } | |
106 | ||
107 | /* | |
108 | * Dispatcher for the VMCI_EVENT_RECEIVE datagrams. Calls all | |
109 | * subscribers for given event. | |
110 | */ | |
111 | int vmci_event_dispatch(struct vmci_datagram *msg) | |
112 | { | |
113 | struct vmci_event_msg *event_msg = (struct vmci_event_msg *)msg; | |
114 | ||
115 | if (msg->payload_size < sizeof(u32) || | |
116 | msg->payload_size > sizeof(struct vmci_event_data_max)) | |
117 | return VMCI_ERROR_INVALID_ARGS; | |
118 | ||
119 | if (!VMCI_EVENT_VALID(event_msg->event_data.event)) | |
120 | return VMCI_ERROR_EVENT_UNKNOWN; | |
121 | ||
122 | event_deliver(event_msg); | |
123 | return VMCI_SUCCESS; | |
124 | } | |
125 | ||
126 | /* | |
127 | * vmci_event_subscribe() - Subscribe to a given event. | |
128 | * @event: The event to subscribe to. | |
129 | * @callback: The callback to invoke upon the event. | |
130 | * @callback_data: Data to pass to the callback. | |
131 | * @subscription_id: ID used to track subscription. Used with | |
132 | * vmci_event_unsubscribe() | |
133 | * | |
134 | * Subscribes to the provided event. The callback specified will be | |
135 | * fired from RCU critical section and therefore must not sleep. | |
136 | */ | |
137 | int vmci_event_subscribe(u32 event, | |
138 | vmci_event_cb callback, | |
139 | void *callback_data, | |
140 | u32 *new_subscription_id) | |
141 | { | |
142 | struct vmci_subscription *sub; | |
143 | int attempts; | |
144 | int retval; | |
145 | bool have_new_id = false; | |
146 | ||
147 | if (!new_subscription_id) { | |
148 | pr_devel("%s: Invalid subscription (NULL)\n", __func__); | |
149 | return VMCI_ERROR_INVALID_ARGS; | |
150 | } | |
151 | ||
152 | if (!VMCI_EVENT_VALID(event) || !callback) { | |
153 | pr_devel("%s: Failed to subscribe to event (type=%d) (callback=%p) (data=%p)\n", | |
154 | __func__, event, callback, callback_data); | |
155 | return VMCI_ERROR_INVALID_ARGS; | |
156 | } | |
157 | ||
158 | sub = kzalloc(sizeof(*sub), GFP_KERNEL); | |
159 | if (!sub) | |
160 | return VMCI_ERROR_NO_MEM; | |
161 | ||
162 | sub->id = VMCI_EVENT_MAX; | |
163 | sub->event = event; | |
164 | sub->callback = callback; | |
165 | sub->callback_data = callback_data; | |
166 | INIT_LIST_HEAD(&sub->node); | |
167 | ||
168 | mutex_lock(&subscriber_mutex); | |
169 | ||
170 | /* Creation of a new event is always allowed. */ | |
171 | for (attempts = 0; attempts < VMCI_EVENT_MAX_ATTEMPTS; attempts++) { | |
172 | static u32 subscription_id; | |
173 | /* | |
174 | * We try to get an id a couple of time before | |
175 | * claiming we are out of resources. | |
176 | */ | |
177 | ||
178 | /* Test for duplicate id. */ | |
179 | if (!event_find(++subscription_id)) { | |
180 | sub->id = subscription_id; | |
181 | have_new_id = true; | |
182 | break; | |
183 | } | |
184 | } | |
185 | ||
186 | if (have_new_id) { | |
187 | list_add_rcu(&sub->node, &subscriber_array[event]); | |
188 | retval = VMCI_SUCCESS; | |
189 | } else { | |
190 | retval = VMCI_ERROR_NO_RESOURCES; | |
191 | } | |
192 | ||
193 | mutex_unlock(&subscriber_mutex); | |
194 | ||
195 | *new_subscription_id = sub->id; | |
196 | return retval; | |
197 | } | |
198 | EXPORT_SYMBOL_GPL(vmci_event_subscribe); | |
199 | ||
200 | /* | |
201 | * vmci_event_unsubscribe() - unsubscribe from an event. | |
202 | * @sub_id: A subscription ID as provided by vmci_event_subscribe() | |
203 | * | |
204 | * Unsubscribe from given event. Removes it from list and frees it. | |
205 | * Will return callback_data if requested by caller. | |
206 | */ | |
207 | int vmci_event_unsubscribe(u32 sub_id) | |
208 | { | |
209 | struct vmci_subscription *s; | |
210 | ||
211 | mutex_lock(&subscriber_mutex); | |
212 | s = event_find(sub_id); | |
213 | if (s) | |
214 | list_del_rcu(&s->node); | |
215 | mutex_unlock(&subscriber_mutex); | |
216 | ||
217 | if (!s) | |
218 | return VMCI_ERROR_NOT_FOUND; | |
219 | ||
220 | synchronize_rcu(); | |
221 | kfree(s); | |
222 | ||
223 | return VMCI_SUCCESS; | |
224 | } | |
225 | EXPORT_SYMBOL_GPL(vmci_event_unsubscribe); |