1 /*
2 * Copyright (C) 2003-2008 Takahiro Hirofuchi
3 * Copyright (C) 2015 Nobuo Iwata
4 *
5 * This is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
18 * USA.
19 */
20
21 #include <linux/kthread.h>
22 #include <linux/export.h>
23 #include <linux/slab.h>
24 #include <linux/workqueue.h>
25
26 #include "usbip_common.h"
27
28 struct usbip_event {
29 struct list_head node;
30 struct usbip_device *ud;
31 };
32
33 static DEFINE_SPINLOCK(event_lock);
34 static LIST_HEAD(event_list);
35
set_event(struct usbip_device * ud,unsigned long event)36 static void set_event(struct usbip_device *ud, unsigned long event)
37 {
38 unsigned long flags;
39
40 spin_lock_irqsave(&ud->lock, flags);
41 ud->event |= event;
42 spin_unlock_irqrestore(&ud->lock, flags);
43 }
44
unset_event(struct usbip_device * ud,unsigned long event)45 static void unset_event(struct usbip_device *ud, unsigned long event)
46 {
47 unsigned long flags;
48
49 spin_lock_irqsave(&ud->lock, flags);
50 ud->event &= ~event;
51 spin_unlock_irqrestore(&ud->lock, flags);
52 }
53
get_event(void)54 static struct usbip_device *get_event(void)
55 {
56 struct usbip_event *ue = NULL;
57 struct usbip_device *ud = NULL;
58 unsigned long flags;
59
60 spin_lock_irqsave(&event_lock, flags);
61 if (!list_empty(&event_list)) {
62 ue = list_first_entry(&event_list, struct usbip_event, node);
63 list_del(&ue->node);
64 }
65 spin_unlock_irqrestore(&event_lock, flags);
66
67 if (ue) {
68 ud = ue->ud;
69 kfree(ue);
70 }
71 return ud;
72 }
73
74 static struct task_struct *worker_context;
75
event_handler(struct work_struct * work)76 static void event_handler(struct work_struct *work)
77 {
78 struct usbip_device *ud;
79
80 if (worker_context == NULL) {
81 worker_context = current;
82 }
83
84 while ((ud = get_event()) != NULL) {
85 usbip_dbg_eh("pending event %lx\n", ud->event);
86
87 /*
88 * NOTE: shutdown must come first.
89 * Shutdown the device.
90 */
91 if (ud->event & USBIP_EH_SHUTDOWN) {
92 ud->eh_ops.shutdown(ud);
93 unset_event(ud, USBIP_EH_SHUTDOWN);
94 }
95
96 /* Reset the device. */
97 if (ud->event & USBIP_EH_RESET) {
98 ud->eh_ops.reset(ud);
99 unset_event(ud, USBIP_EH_RESET);
100 }
101
102 /* Mark the device as unusable. */
103 if (ud->event & USBIP_EH_UNUSABLE) {
104 ud->eh_ops.unusable(ud);
105 unset_event(ud, USBIP_EH_UNUSABLE);
106 }
107
108 /* Stop the error handler. */
109 if (ud->event & USBIP_EH_BYE)
110 usbip_dbg_eh("removed %p\n", ud);
111
112 wake_up(&ud->eh_waitq);
113 }
114 }
115
usbip_start_eh(struct usbip_device * ud)116 int usbip_start_eh(struct usbip_device *ud)
117 {
118 init_waitqueue_head(&ud->eh_waitq);
119 ud->event = 0;
120 return 0;
121 }
122 EXPORT_SYMBOL_GPL(usbip_start_eh);
123
usbip_stop_eh(struct usbip_device * ud)124 void usbip_stop_eh(struct usbip_device *ud)
125 {
126 unsigned long pending = ud->event & ~USBIP_EH_BYE;
127
128 if (!(ud->event & USBIP_EH_BYE))
129 usbip_dbg_eh("usbip_eh stopping but not removed\n");
130
131 if (pending)
132 usbip_dbg_eh("usbip_eh waiting completion %lx\n", pending);
133
134 wait_event_interruptible(ud->eh_waitq, !(ud->event & ~USBIP_EH_BYE));
135 usbip_dbg_eh("usbip_eh has stopped\n");
136 }
137 EXPORT_SYMBOL_GPL(usbip_stop_eh);
138
139 #define WORK_QUEUE_NAME "usbip_event"
140
141 static struct workqueue_struct *usbip_queue;
142 static DECLARE_WORK(usbip_work, event_handler);
143
usbip_init_eh(void)144 int usbip_init_eh(void)
145 {
146 usbip_queue = create_singlethread_workqueue(WORK_QUEUE_NAME);
147 if (usbip_queue == NULL) {
148 pr_err("failed to create usbip_event\n");
149 return -ENOMEM;
150 }
151 return 0;
152 }
153
usbip_finish_eh(void)154 void usbip_finish_eh(void)
155 {
156 flush_workqueue(usbip_queue);
157 destroy_workqueue(usbip_queue);
158 usbip_queue = NULL;
159 }
160
usbip_event_add(struct usbip_device * ud,unsigned long event)161 void usbip_event_add(struct usbip_device *ud, unsigned long event)
162 {
163 struct usbip_event *ue;
164 unsigned long flags;
165
166 if (ud->event & USBIP_EH_BYE)
167 return;
168
169 set_event(ud, event);
170
171 spin_lock_irqsave(&event_lock, flags);
172
173 list_for_each_entry_reverse(ue, &event_list, node) {
174 if (ue->ud == ud)
175 goto out;
176 }
177
178 ue = kmalloc(sizeof(struct usbip_event), GFP_ATOMIC);
179 if (ue == NULL)
180 goto out;
181
182 ue->ud = ud;
183
184 list_add_tail(&ue->node, &event_list);
185 queue_work(usbip_queue, &usbip_work);
186
187 out:
188 spin_unlock_irqrestore(&event_lock, flags);
189 }
190 EXPORT_SYMBOL_GPL(usbip_event_add);
191
usbip_event_happened(struct usbip_device * ud)192 int usbip_event_happened(struct usbip_device *ud)
193 {
194 int happened = 0;
195 unsigned long flags;
196
197 spin_lock_irqsave(&ud->lock, flags);
198 if (ud->event != 0)
199 happened = 1;
200 spin_unlock_irqrestore(&ud->lock, flags);
201
202 return happened;
203 }
204 EXPORT_SYMBOL_GPL(usbip_event_happened);
205
usbip_in_eh(struct task_struct * task)206 int usbip_in_eh(struct task_struct *task)
207 {
208 if (task == worker_context)
209 return 1;
210
211 return 0;
212 }
213 EXPORT_SYMBOL_GPL(usbip_in_eh);
214