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 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 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 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 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 } 115 116 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); 123 124 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); 143 144 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 } 153 154 void usbip_finish_eh(void) 155 { 156 flush_workqueue(usbip_queue); 157 destroy_workqueue(usbip_queue); 158 usbip_queue = NULL; 159 } 160 161 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); 191 192 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); 205 206 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