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685a6bf8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1d990201 GZ |
2 | /* |
3 | * VMware VMCI Driver | |
4 | * | |
5 | * Copyright (C) 2012 VMware, Inc. All rights reserved. | |
1d990201 GZ |
6 | */ |
7 | ||
8 | #include <linux/vmw_vmci_defs.h> | |
9 | #include <linux/vmw_vmci_api.h> | |
10 | #include <linux/list.h> | |
11 | #include <linux/module.h> | |
12 | #include <linux/sched.h> | |
13 | #include <linux/slab.h> | |
b2d09103 | 14 | #include <linux/rculist.h> |
1d990201 GZ |
15 | |
16 | #include "vmci_driver.h" | |
17 | #include "vmci_event.h" | |
18 | ||
19 | #define EVENT_MAGIC 0xEABE0000 | |
20 | #define VMCI_EVENT_MAX_ATTEMPTS 10 | |
21 | ||
22 | struct vmci_subscription { | |
23 | u32 id; | |
24 | u32 event; | |
25 | vmci_event_cb callback; | |
26 | void *callback_data; | |
27 | struct list_head node; /* on one of subscriber lists */ | |
28 | }; | |
29 | ||
30 | static struct list_head subscriber_array[VMCI_EVENT_MAX]; | |
31 | static DEFINE_MUTEX(subscriber_mutex); | |
32 | ||
33 | int __init vmci_event_init(void) | |
34 | { | |
35 | int i; | |
36 | ||
37 | for (i = 0; i < VMCI_EVENT_MAX; i++) | |
38 | INIT_LIST_HEAD(&subscriber_array[i]); | |
39 | ||
40 | return VMCI_SUCCESS; | |
41 | } | |
42 | ||
43 | void vmci_event_exit(void) | |
44 | { | |
45 | int e; | |
46 | ||
47 | /* We free all memory at exit. */ | |
48 | for (e = 0; e < VMCI_EVENT_MAX; e++) { | |
49 | struct vmci_subscription *cur, *p2; | |
50 | list_for_each_entry_safe(cur, p2, &subscriber_array[e], node) { | |
51 | ||
52 | /* | |
53 | * We should never get here because all events | |
54 | * should have been unregistered before we try | |
55 | * to unload the driver module. | |
56 | */ | |
57 | pr_warn("Unexpected free events occurring\n"); | |
58 | list_del(&cur->node); | |
59 | kfree(cur); | |
60 | } | |
61 | } | |
62 | } | |
63 | ||
64 | /* | |
65 | * Find entry. Assumes subscriber_mutex is held. | |
66 | */ | |
67 | static struct vmci_subscription *event_find(u32 sub_id) | |
68 | { | |
69 | int e; | |
70 | ||
71 | for (e = 0; e < VMCI_EVENT_MAX; e++) { | |
72 | struct vmci_subscription *cur; | |
73 | list_for_each_entry(cur, &subscriber_array[e], node) { | |
74 | if (cur->id == sub_id) | |
75 | return cur; | |
76 | } | |
77 | } | |
78 | return NULL; | |
79 | } | |
80 | ||
81 | /* | |
82 | * Actually delivers the events to the subscribers. | |
83 | * The callback function for each subscriber is invoked. | |
84 | */ | |
85 | static void event_deliver(struct vmci_event_msg *event_msg) | |
86 | { | |
87 | struct vmci_subscription *cur; | |
88 | struct list_head *subscriber_list; | |
89 | ||
90 | rcu_read_lock(); | |
91 | subscriber_list = &subscriber_array[event_msg->event_data.event]; | |
92 | list_for_each_entry_rcu(cur, subscriber_list, node) { | |
93 | cur->callback(cur->id, &event_msg->event_data, | |
94 | cur->callback_data); | |
95 | } | |
96 | rcu_read_unlock(); | |
97 | } | |
98 | ||
99 | /* | |
100 | * Dispatcher for the VMCI_EVENT_RECEIVE datagrams. Calls all | |
101 | * subscribers for given event. | |
102 | */ | |
103 | int vmci_event_dispatch(struct vmci_datagram *msg) | |
104 | { | |
105 | struct vmci_event_msg *event_msg = (struct vmci_event_msg *)msg; | |
106 | ||
107 | if (msg->payload_size < sizeof(u32) || | |
108 | msg->payload_size > sizeof(struct vmci_event_data_max)) | |
109 | return VMCI_ERROR_INVALID_ARGS; | |
110 | ||
111 | if (!VMCI_EVENT_VALID(event_msg->event_data.event)) | |
112 | return VMCI_ERROR_EVENT_UNKNOWN; | |
113 | ||
114 | event_deliver(event_msg); | |
115 | return VMCI_SUCCESS; | |
116 | } | |
117 | ||
118 | /* | |
119 | * vmci_event_subscribe() - Subscribe to a given event. | |
120 | * @event: The event to subscribe to. | |
121 | * @callback: The callback to invoke upon the event. | |
122 | * @callback_data: Data to pass to the callback. | |
123 | * @subscription_id: ID used to track subscription. Used with | |
124 | * vmci_event_unsubscribe() | |
125 | * | |
126 | * Subscribes to the provided event. The callback specified will be | |
127 | * fired from RCU critical section and therefore must not sleep. | |
128 | */ | |
129 | int vmci_event_subscribe(u32 event, | |
130 | vmci_event_cb callback, | |
131 | void *callback_data, | |
132 | u32 *new_subscription_id) | |
133 | { | |
134 | struct vmci_subscription *sub; | |
135 | int attempts; | |
136 | int retval; | |
137 | bool have_new_id = false; | |
138 | ||
139 | if (!new_subscription_id) { | |
140 | pr_devel("%s: Invalid subscription (NULL)\n", __func__); | |
141 | return VMCI_ERROR_INVALID_ARGS; | |
142 | } | |
143 | ||
144 | if (!VMCI_EVENT_VALID(event) || !callback) { | |
145 | pr_devel("%s: Failed to subscribe to event (type=%d) (callback=%p) (data=%p)\n", | |
146 | __func__, event, callback, callback_data); | |
147 | return VMCI_ERROR_INVALID_ARGS; | |
148 | } | |
149 | ||
150 | sub = kzalloc(sizeof(*sub), GFP_KERNEL); | |
151 | if (!sub) | |
152 | return VMCI_ERROR_NO_MEM; | |
153 | ||
154 | sub->id = VMCI_EVENT_MAX; | |
155 | sub->event = event; | |
156 | sub->callback = callback; | |
157 | sub->callback_data = callback_data; | |
158 | INIT_LIST_HEAD(&sub->node); | |
159 | ||
160 | mutex_lock(&subscriber_mutex); | |
161 | ||
162 | /* Creation of a new event is always allowed. */ | |
163 | for (attempts = 0; attempts < VMCI_EVENT_MAX_ATTEMPTS; attempts++) { | |
164 | static u32 subscription_id; | |
165 | /* | |
166 | * We try to get an id a couple of time before | |
167 | * claiming we are out of resources. | |
168 | */ | |
169 | ||
170 | /* Test for duplicate id. */ | |
171 | if (!event_find(++subscription_id)) { | |
172 | sub->id = subscription_id; | |
173 | have_new_id = true; | |
174 | break; | |
175 | } | |
176 | } | |
177 | ||
178 | if (have_new_id) { | |
179 | list_add_rcu(&sub->node, &subscriber_array[event]); | |
180 | retval = VMCI_SUCCESS; | |
181 | } else { | |
182 | retval = VMCI_ERROR_NO_RESOURCES; | |
183 | } | |
184 | ||
185 | mutex_unlock(&subscriber_mutex); | |
186 | ||
187 | *new_subscription_id = sub->id; | |
188 | return retval; | |
189 | } | |
190 | EXPORT_SYMBOL_GPL(vmci_event_subscribe); | |
191 | ||
192 | /* | |
193 | * vmci_event_unsubscribe() - unsubscribe from an event. | |
194 | * @sub_id: A subscription ID as provided by vmci_event_subscribe() | |
195 | * | |
196 | * Unsubscribe from given event. Removes it from list and frees it. | |
197 | * Will return callback_data if requested by caller. | |
198 | */ | |
199 | int vmci_event_unsubscribe(u32 sub_id) | |
200 | { | |
201 | struct vmci_subscription *s; | |
202 | ||
203 | mutex_lock(&subscriber_mutex); | |
204 | s = event_find(sub_id); | |
205 | if (s) | |
206 | list_del_rcu(&s->node); | |
207 | mutex_unlock(&subscriber_mutex); | |
208 | ||
209 | if (!s) | |
210 | return VMCI_ERROR_NOT_FOUND; | |
211 | ||
6da3f337 | 212 | kvfree_rcu(s); |
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213 | |
214 | return VMCI_SUCCESS; | |
215 | } | |
216 | EXPORT_SYMBOL_GPL(vmci_event_unsubscribe); |