1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2003-2008 Takahiro Hirofuchi
4 * Copyright (C) 2015 Nobuo Iwata
5 */
6
7 #include <linux/kthread.h>
8 #include <linux/export.h>
9 #include <linux/slab.h>
10 #include <linux/workqueue.h>
11
12 #include "usbip_common.h"
13
14 struct usbip_event {
15 struct list_head node;
16 struct usbip_device *ud;
17 };
18
19 static DEFINE_SPINLOCK(event_lock);
20 static LIST_HEAD(event_list);
21
set_event(struct usbip_device * ud,unsigned long event)22 static void set_event(struct usbip_device *ud, unsigned long event)
23 {
24 unsigned long flags;
25
26 spin_lock_irqsave(&ud->lock, flags);
27 ud->event |= event;
28 spin_unlock_irqrestore(&ud->lock, flags);
29 }
30
unset_event(struct usbip_device * ud,unsigned long event)31 static void unset_event(struct usbip_device *ud, unsigned long event)
32 {
33 unsigned long flags;
34
35 spin_lock_irqsave(&ud->lock, flags);
36 ud->event &= ~event;
37 spin_unlock_irqrestore(&ud->lock, flags);
38 }
39
get_event(void)40 static struct usbip_device *get_event(void)
41 {
42 struct usbip_event *ue = NULL;
43 struct usbip_device *ud = NULL;
44 unsigned long flags;
45
46 spin_lock_irqsave(&event_lock, flags);
47 if (!list_empty(&event_list)) {
48 ue = list_first_entry(&event_list, struct usbip_event, node);
49 list_del(&ue->node);
50 }
51 spin_unlock_irqrestore(&event_lock, flags);
52
53 if (ue) {
54 ud = ue->ud;
55 kfree(ue);
56 }
57 return ud;
58 }
59
60 static struct task_struct *worker_context;
61
event_handler(struct work_struct * work)62 static void event_handler(struct work_struct *work)
63 {
64 struct usbip_device *ud;
65
66 if (worker_context == NULL) {
67 worker_context = current;
68 }
69
70 while ((ud = get_event()) != NULL) {
71 usbip_dbg_eh("pending event %lx\n", ud->event);
72
73 /*
74 * NOTE: shutdown must come first.
75 * Shutdown the device.
76 */
77 if (ud->event & USBIP_EH_SHUTDOWN) {
78 ud->eh_ops.shutdown(ud);
79 unset_event(ud, USBIP_EH_SHUTDOWN);
80 }
81
82 /* Reset the device. */
83 if (ud->event & USBIP_EH_RESET) {
84 ud->eh_ops.reset(ud);
85 unset_event(ud, USBIP_EH_RESET);
86 }
87
88 /* Mark the device as unusable. */
89 if (ud->event & USBIP_EH_UNUSABLE) {
90 ud->eh_ops.unusable(ud);
91 unset_event(ud, USBIP_EH_UNUSABLE);
92 }
93
94 wake_up(&ud->eh_waitq);
95 }
96 }
97
usbip_start_eh(struct usbip_device * ud)98 int usbip_start_eh(struct usbip_device *ud)
99 {
100 init_waitqueue_head(&ud->eh_waitq);
101 ud->event = 0;
102 return 0;
103 }
104 EXPORT_SYMBOL_GPL(usbip_start_eh);
105
usbip_stop_eh(struct usbip_device * ud)106 void usbip_stop_eh(struct usbip_device *ud)
107 {
108 unsigned long pending = ud->event & ~USBIP_EH_BYE;
109
110 if (!(ud->event & USBIP_EH_BYE))
111 usbip_dbg_eh("usbip_eh stopping but not removed\n");
112
113 if (pending)
114 usbip_dbg_eh("usbip_eh waiting completion %lx\n", pending);
115
116 wait_event_interruptible(ud->eh_waitq, !(ud->event & ~USBIP_EH_BYE));
117 usbip_dbg_eh("usbip_eh has stopped\n");
118 }
119 EXPORT_SYMBOL_GPL(usbip_stop_eh);
120
121 #define WORK_QUEUE_NAME "usbip_event"
122
123 static struct workqueue_struct *usbip_queue;
124 static DECLARE_WORK(usbip_work, event_handler);
125
usbip_init_eh(void)126 int usbip_init_eh(void)
127 {
128 usbip_queue = create_singlethread_workqueue(WORK_QUEUE_NAME);
129 if (usbip_queue == NULL) {
130 pr_err("failed to create usbip_event\n");
131 return -ENOMEM;
132 }
133 return 0;
134 }
135
usbip_finish_eh(void)136 void usbip_finish_eh(void)
137 {
138 flush_workqueue(usbip_queue);
139 destroy_workqueue(usbip_queue);
140 usbip_queue = NULL;
141 }
142
usbip_event_add(struct usbip_device * ud,unsigned long event)143 void usbip_event_add(struct usbip_device *ud, unsigned long event)
144 {
145 struct usbip_event *ue;
146 unsigned long flags;
147
148 if (ud->event & USBIP_EH_BYE)
149 return;
150
151 set_event(ud, event);
152
153 spin_lock_irqsave(&event_lock, flags);
154
155 list_for_each_entry_reverse(ue, &event_list, node) {
156 if (ue->ud == ud)
157 goto out;
158 }
159
160 ue = kmalloc(sizeof(struct usbip_event), GFP_ATOMIC);
161 if (ue == NULL)
162 goto out;
163
164 ue->ud = ud;
165
166 list_add_tail(&ue->node, &event_list);
167 queue_work(usbip_queue, &usbip_work);
168
169 out:
170 spin_unlock_irqrestore(&event_lock, flags);
171 }
172 EXPORT_SYMBOL_GPL(usbip_event_add);
173
usbip_event_happened(struct usbip_device * ud)174 int usbip_event_happened(struct usbip_device *ud)
175 {
176 int happened = 0;
177 unsigned long flags;
178
179 spin_lock_irqsave(&ud->lock, flags);
180 if (ud->event != 0)
181 happened = 1;
182 spin_unlock_irqrestore(&ud->lock, flags);
183
184 return happened;
185 }
186 EXPORT_SYMBOL_GPL(usbip_event_happened);
187
usbip_in_eh(struct task_struct * task)188 int usbip_in_eh(struct task_struct *task)
189 {
190 if (task == worker_context)
191 return 1;
192
193 return 0;
194 }
195 EXPORT_SYMBOL_GPL(usbip_in_eh);
196
