drivers/usb/usbip/usbip_event.c

   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);