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685a6bf8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
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2 | /* |
3 | * VMware VMCI Driver | |
4 | * | |
5 | * Copyright (C) 2012 VMware, Inc. All rights reserved. | |
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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> | |
8003f00d | 12 | #include <linux/nospec.h> |
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13 | #include <linux/sched.h> |
14 | #include <linux/slab.h> | |
b2d09103 | 15 | #include <linux/rculist.h> |
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16 | |
17 | #include "vmci_driver.h" | |
18 | #include "vmci_event.h" | |
19 | ||
20 | #define EVENT_MAGIC 0xEABE0000 | |
21 | #define VMCI_EVENT_MAX_ATTEMPTS 10 | |
22 | ||
23 | struct vmci_subscription { | |
24 | u32 id; | |
25 | u32 event; | |
26 | vmci_event_cb callback; | |
27 | void *callback_data; | |
28 | struct list_head node; /* on one of subscriber lists */ | |
29 | }; | |
30 | ||
31 | static struct list_head subscriber_array[VMCI_EVENT_MAX]; | |
32 | static DEFINE_MUTEX(subscriber_mutex); | |
33 | ||
34 | int __init vmci_event_init(void) | |
35 | { | |
36 | int i; | |
37 | ||
38 | for (i = 0; i < VMCI_EVENT_MAX; i++) | |
39 | INIT_LIST_HEAD(&subscriber_array[i]); | |
40 | ||
41 | return VMCI_SUCCESS; | |
42 | } | |
43 | ||
44 | void vmci_event_exit(void) | |
45 | { | |
46 | int e; | |
47 | ||
48 | /* We free all memory at exit. */ | |
49 | for (e = 0; e < VMCI_EVENT_MAX; e++) { | |
50 | struct vmci_subscription *cur, *p2; | |
51 | list_for_each_entry_safe(cur, p2, &subscriber_array[e], node) { | |
52 | ||
53 | /* | |
54 | * We should never get here because all events | |
55 | * should have been unregistered before we try | |
56 | * to unload the driver module. | |
57 | */ | |
58 | pr_warn("Unexpected free events occurring\n"); | |
59 | list_del(&cur->node); | |
60 | kfree(cur); | |
61 | } | |
62 | } | |
63 | } | |
64 | ||
65 | /* | |
66 | * Find entry. Assumes subscriber_mutex is held. | |
67 | */ | |
68 | static struct vmci_subscription *event_find(u32 sub_id) | |
69 | { | |
70 | int e; | |
71 | ||
72 | for (e = 0; e < VMCI_EVENT_MAX; e++) { | |
73 | struct vmci_subscription *cur; | |
74 | list_for_each_entry(cur, &subscriber_array[e], node) { | |
75 | if (cur->id == sub_id) | |
76 | return cur; | |
77 | } | |
78 | } | |
79 | return NULL; | |
80 | } | |
81 | ||
82 | /* | |
83 | * Actually delivers the events to the subscribers. | |
84 | * The callback function for each subscriber is invoked. | |
85 | */ | |
86 | static void event_deliver(struct vmci_event_msg *event_msg) | |
87 | { | |
88 | struct vmci_subscription *cur; | |
89 | struct list_head *subscriber_list; | |
8003f00d | 90 | u32 sanitized_event, max_vmci_event; |
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91 | |
92 | rcu_read_lock(); | |
8003f00d HGHH |
93 | max_vmci_event = ARRAY_SIZE(subscriber_array); |
94 | sanitized_event = array_index_nospec(event_msg->event_data.event, max_vmci_event); | |
95 | subscriber_list = &subscriber_array[sanitized_event]; | |
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96 | list_for_each_entry_rcu(cur, subscriber_list, node) { |
97 | cur->callback(cur->id, &event_msg->event_data, | |
98 | cur->callback_data); | |
99 | } | |
100 | rcu_read_unlock(); | |
101 | } | |
102 | ||
103 | /* | |
104 | * Dispatcher for the VMCI_EVENT_RECEIVE datagrams. Calls all | |
105 | * subscribers for given event. | |
106 | */ | |
107 | int vmci_event_dispatch(struct vmci_datagram *msg) | |
108 | { | |
109 | struct vmci_event_msg *event_msg = (struct vmci_event_msg *)msg; | |
110 | ||
111 | if (msg->payload_size < sizeof(u32) || | |
112 | msg->payload_size > sizeof(struct vmci_event_data_max)) | |
113 | return VMCI_ERROR_INVALID_ARGS; | |
114 | ||
115 | if (!VMCI_EVENT_VALID(event_msg->event_data.event)) | |
116 | return VMCI_ERROR_EVENT_UNKNOWN; | |
117 | ||
118 | event_deliver(event_msg); | |
119 | return VMCI_SUCCESS; | |
120 | } | |
121 | ||
122 | /* | |
123 | * vmci_event_subscribe() - Subscribe to a given event. | |
124 | * @event: The event to subscribe to. | |
125 | * @callback: The callback to invoke upon the event. | |
126 | * @callback_data: Data to pass to the callback. | |
127 | * @subscription_id: ID used to track subscription. Used with | |
128 | * vmci_event_unsubscribe() | |
129 | * | |
130 | * Subscribes to the provided event. The callback specified will be | |
131 | * fired from RCU critical section and therefore must not sleep. | |
132 | */ | |
133 | int vmci_event_subscribe(u32 event, | |
134 | vmci_event_cb callback, | |
135 | void *callback_data, | |
136 | u32 *new_subscription_id) | |
137 | { | |
138 | struct vmci_subscription *sub; | |
139 | int attempts; | |
140 | int retval; | |
141 | bool have_new_id = false; | |
142 | ||
143 | if (!new_subscription_id) { | |
144 | pr_devel("%s: Invalid subscription (NULL)\n", __func__); | |
145 | return VMCI_ERROR_INVALID_ARGS; | |
146 | } | |
147 | ||
148 | if (!VMCI_EVENT_VALID(event) || !callback) { | |
149 | pr_devel("%s: Failed to subscribe to event (type=%d) (callback=%p) (data=%p)\n", | |
150 | __func__, event, callback, callback_data); | |
151 | return VMCI_ERROR_INVALID_ARGS; | |
152 | } | |
153 | ||
154 | sub = kzalloc(sizeof(*sub), GFP_KERNEL); | |
155 | if (!sub) | |
156 | return VMCI_ERROR_NO_MEM; | |
157 | ||
158 | sub->id = VMCI_EVENT_MAX; | |
159 | sub->event = event; | |
160 | sub->callback = callback; | |
161 | sub->callback_data = callback_data; | |
162 | INIT_LIST_HEAD(&sub->node); | |
163 | ||
164 | mutex_lock(&subscriber_mutex); | |
165 | ||
166 | /* Creation of a new event is always allowed. */ | |
167 | for (attempts = 0; attempts < VMCI_EVENT_MAX_ATTEMPTS; attempts++) { | |
168 | static u32 subscription_id; | |
169 | /* | |
170 | * We try to get an id a couple of time before | |
171 | * claiming we are out of resources. | |
172 | */ | |
173 | ||
174 | /* Test for duplicate id. */ | |
175 | if (!event_find(++subscription_id)) { | |
176 | sub->id = subscription_id; | |
177 | have_new_id = true; | |
178 | break; | |
179 | } | |
180 | } | |
181 | ||
182 | if (have_new_id) { | |
183 | list_add_rcu(&sub->node, &subscriber_array[event]); | |
184 | retval = VMCI_SUCCESS; | |
185 | } else { | |
186 | retval = VMCI_ERROR_NO_RESOURCES; | |
187 | } | |
188 | ||
189 | mutex_unlock(&subscriber_mutex); | |
190 | ||
191 | *new_subscription_id = sub->id; | |
192 | return retval; | |
193 | } | |
194 | EXPORT_SYMBOL_GPL(vmci_event_subscribe); | |
195 | ||
196 | /* | |
197 | * vmci_event_unsubscribe() - unsubscribe from an event. | |
198 | * @sub_id: A subscription ID as provided by vmci_event_subscribe() | |
199 | * | |
200 | * Unsubscribe from given event. Removes it from list and frees it. | |
201 | * Will return callback_data if requested by caller. | |
202 | */ | |
203 | int vmci_event_unsubscribe(u32 sub_id) | |
204 | { | |
205 | struct vmci_subscription *s; | |
206 | ||
207 | mutex_lock(&subscriber_mutex); | |
208 | s = event_find(sub_id); | |
209 | if (s) | |
210 | list_del_rcu(&s->node); | |
211 | mutex_unlock(&subscriber_mutex); | |
212 | ||
213 | if (!s) | |
214 | return VMCI_ERROR_NOT_FOUND; | |
215 | ||
09b2286a | 216 | kvfree_rcu_mightsleep(s); |
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217 | |
218 | return VMCI_SUCCESS; | |
219 | } | |
220 | EXPORT_SYMBOL_GPL(vmci_event_unsubscribe); |