1/*
2 * Copyright (C) 2003-2008 Takahiro Hirofuchi
3 *
4 * This is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
17 * USA.
18 */
19
20#include <linux/kthread.h>
21#include <linux/export.h>
22
23#include "usbip_common.h"
24
25static int event_handler(struct usbip_device *ud)
26{
27	usbip_dbg_eh("enter\n");
28
29	/*
30	 * Events are handled by only this thread.
31	 */
32	while (usbip_event_happened(ud)) {
33		usbip_dbg_eh("pending event %lx\n", ud->event);
34
35		/*
36		 * NOTE: shutdown must come first.
37		 * Shutdown the device.
38		 */
39		if (ud->event & USBIP_EH_SHUTDOWN) {
40			ud->eh_ops.shutdown(ud);
41			ud->event &= ~USBIP_EH_SHUTDOWN;
42		}
43
44		/* Reset the device. */
45		if (ud->event & USBIP_EH_RESET) {
46			ud->eh_ops.reset(ud);
47			ud->event &= ~USBIP_EH_RESET;
48		}
49
50		/* Mark the device as unusable. */
51		if (ud->event & USBIP_EH_UNUSABLE) {
52			ud->eh_ops.unusable(ud);
53			ud->event &= ~USBIP_EH_UNUSABLE;
54		}
55
56		/* Stop the error handler. */
57		if (ud->event & USBIP_EH_BYE)
58			return -1;
59	}
60
61	return 0;
62}
63
64static int event_handler_loop(void *data)
65{
66	struct usbip_device *ud = data;
67
68	while (!kthread_should_stop()) {
69		wait_event_interruptible(ud->eh_waitq,
70					 usbip_event_happened(ud) ||
71					 kthread_should_stop());
72		usbip_dbg_eh("wakeup\n");
73
74		if (event_handler(ud) < 0)
75			break;
76	}
77
78	return 0;
79}
80
81int usbip_start_eh(struct usbip_device *ud)
82{
83	init_waitqueue_head(&ud->eh_waitq);
84	ud->event = 0;
85
86	ud->eh = kthread_run(event_handler_loop, ud, "usbip_eh");
87	if (IS_ERR(ud->eh)) {
88		pr_warn("Unable to start control thread\n");
89		return PTR_ERR(ud->eh);
90	}
91
92	return 0;
93}
94EXPORT_SYMBOL_GPL(usbip_start_eh);
95
96void usbip_stop_eh(struct usbip_device *ud)
97{
98	if (ud->eh == current)
99		return; /* do not wait for myself */
100
101	kthread_stop(ud->eh);
102	usbip_dbg_eh("usbip_eh has finished\n");
103}
104EXPORT_SYMBOL_GPL(usbip_stop_eh);
105
106void usbip_event_add(struct usbip_device *ud, unsigned long event)
107{
108	unsigned long flags;
109
110	spin_lock_irqsave(&ud->lock, flags);
111	ud->event |= event;
112	wake_up(&ud->eh_waitq);
113	spin_unlock_irqrestore(&ud->lock, flags);
114}
115EXPORT_SYMBOL_GPL(usbip_event_add);
116
117int usbip_event_happened(struct usbip_device *ud)
118{
119	int happened = 0;
120
121	spin_lock(&ud->lock);
122	if (ud->event != 0)
123		happened = 1;
124	spin_unlock(&ud->lock);
125
126	return happened;
127}
128EXPORT_SYMBOL_GPL(usbip_event_happened);
129