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 mutex_lock(&ud->sysfs_lock);
74 /*
75 * NOTE: shutdown must come first.
76 * Shutdown the device.
77 */
78 if (ud->event & USBIP_EH_SHUTDOWN) {
79 ud->eh_ops.shutdown(ud);
80 unset_event(ud, USBIP_EH_SHUTDOWN);
81 }
82
83 /* Reset the device. */
84 if (ud->event & USBIP_EH_RESET) {
85 ud->eh_ops.reset(ud);
86 unset_event(ud, USBIP_EH_RESET);
87 }
88
89 /* Mark the device as unusable. */
90 if (ud->event & USBIP_EH_UNUSABLE) {
91 ud->eh_ops.unusable(ud);
92 unset_event(ud, USBIP_EH_UNUSABLE);
93 }
94 mutex_unlock(&ud->sysfs_lock);
95
96 wake_up(&ud->eh_waitq);
97 }
98 }
99
usbip_start_eh(struct usbip_device * ud)100 int usbip_start_eh(struct usbip_device *ud)
101 {
102 init_waitqueue_head(&ud->eh_waitq);
103 ud->event = 0;
104 return 0;
105 }
106 EXPORT_SYMBOL_GPL(usbip_start_eh);
107
usbip_stop_eh(struct usbip_device * ud)108 void usbip_stop_eh(struct usbip_device *ud)
109 {
110 unsigned long pending = ud->event & ~USBIP_EH_BYE;
111
112 if (!(ud->event & USBIP_EH_BYE))
113 usbip_dbg_eh("usbip_eh stopping but not removed\n");
114
115 if (pending)
116 usbip_dbg_eh("usbip_eh waiting completion %lx\n", pending);
117
118 wait_event_interruptible(ud->eh_waitq, !(ud->event & ~USBIP_EH_BYE));
119 usbip_dbg_eh("usbip_eh has stopped\n");
120 }
121 EXPORT_SYMBOL_GPL(usbip_stop_eh);
122
123 #define WORK_QUEUE_NAME "usbip_event"
124
125 static struct workqueue_struct *usbip_queue;
126 static DECLARE_WORK(usbip_work, event_handler);
127
usbip_init_eh(void)128 int usbip_init_eh(void)
129 {
130 usbip_queue = create_singlethread_workqueue(WORK_QUEUE_NAME);
131 if (usbip_queue == NULL) {
132 pr_err("failed to create usbip_event\n");
133 return -ENOMEM;
134 }
135 return 0;
136 }
137
usbip_finish_eh(void)138 void usbip_finish_eh(void)
139 {
140 destroy_workqueue(usbip_queue);
141 usbip_queue = NULL;
142 }
143
usbip_event_add(struct usbip_device * ud,unsigned long event)144 void usbip_event_add(struct usbip_device *ud, unsigned long event)
145 {
146 struct usbip_event *ue;
147 unsigned long flags;
148
149 if (ud->event & USBIP_EH_BYE)
150 return;
151
152 set_event(ud, event);
153
154 spin_lock_irqsave(&event_lock, flags);
155
156 list_for_each_entry_reverse(ue, &event_list, node) {
157 if (ue->ud == ud)
158 goto out;
159 }
160
161 ue = kmalloc(sizeof(struct usbip_event), GFP_ATOMIC);
162 if (ue == NULL)
163 goto out;
164
165 ue->ud = ud;
166
167 list_add_tail(&ue->node, &event_list);
168 queue_work(usbip_queue, &usbip_work);
169
170 out:
171 spin_unlock_irqrestore(&event_lock, flags);
172 }
173 EXPORT_SYMBOL_GPL(usbip_event_add);
174
usbip_event_happened(struct usbip_device * ud)175 int usbip_event_happened(struct usbip_device *ud)
176 {
177 int happened = 0;
178 unsigned long flags;
179
180 spin_lock_irqsave(&ud->lock, flags);
181 if (ud->event != 0)
182 happened = 1;
183 spin_unlock_irqrestore(&ud->lock, flags);
184
185 return happened;
186 }
187 EXPORT_SYMBOL_GPL(usbip_event_happened);
188
usbip_in_eh(struct task_struct * task)189 int usbip_in_eh(struct task_struct *task)
190 {
191 if (task == worker_context)
192 return 1;
193
194 return 0;
195 }
196 EXPORT_SYMBOL_GPL(usbip_in_eh);
197