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
 14struct usbip_event {
 15	struct list_head node;
 16	struct usbip_device *ud;
 17};
 18
 19static DEFINE_SPINLOCK(event_lock);
 20static LIST_HEAD(event_list);
 21
 22static 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
 31static 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
 40static 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
 60static struct task_struct *worker_context;
 61
 62static 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
100int usbip_start_eh(struct usbip_device *ud)
101{
102	init_waitqueue_head(&ud->eh_waitq);
103	ud->event = 0;
104	return 0;
105}
106EXPORT_SYMBOL_GPL(usbip_start_eh);
107
108void 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}
121EXPORT_SYMBOL_GPL(usbip_stop_eh);
122
123#define WORK_QUEUE_NAME "usbip_event"
124
125static struct workqueue_struct *usbip_queue;
126static DECLARE_WORK(usbip_work, event_handler);
127
128int 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
138void usbip_finish_eh(void)
139{
140	destroy_workqueue(usbip_queue);
141	usbip_queue = NULL;
142}
143
144void 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
170out:
171	spin_unlock_irqrestore(&event_lock, flags);
172}
173EXPORT_SYMBOL_GPL(usbip_event_add);
174
175int 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}
187EXPORT_SYMBOL_GPL(usbip_event_happened);
188
189int usbip_in_eh(struct task_struct *task)
190{
191	if (task == worker_context)
192		return 1;
193
194	return 0;
195}
196EXPORT_SYMBOL_GPL(usbip_in_eh);