drivers/staging/usbip/usbip_event.c

   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 "usbip_common.h"
  21 #include <linux/kthread.h>
  22
  23 static int event_handler(struct usbip_device *ud)
  24 {
  25         usbip_dbg_eh("enter\n");
  26
  27         /*
  28          * Events are handled by only this thread.
  29          */
  30         while (usbip_event_happened(ud)) {
  31                 usbip_dbg_eh("pending event %lx\n", ud->event);
  32
  33                 /*
  34                  * NOTE: shutdown must come first.
  35                  * Shutdown the device.
  36                  */
  37                 if (ud->event & USBIP_EH_SHUTDOWN) {
  38                         ud->eh_ops.shutdown(ud);
  39
  40                         ud->event &= ~USBIP_EH_SHUTDOWN;
  41
  42                         break;
  43                 }
  44
  45                 /* Stop the error handler. */
  46                 if (ud->event & USBIP_EH_BYE)
  47                         return -1;
  48
  49                 /* Reset the device. */
  50                 if (ud->event & USBIP_EH_RESET) {
  51                         ud->eh_ops.reset(ud);
  52
  53                         ud->event &= ~USBIP_EH_RESET;
  54
  55                         break;
  56                 }
  57
  58                 /* Mark the device as unusable. */
  59                 if (ud->event & USBIP_EH_UNUSABLE) {
  60                         ud->eh_ops.unusable(ud);
  61
  62                         ud->event &= ~USBIP_EH_UNUSABLE;
  63
  64                         break;
  65                 }
  66
  67                 /* NOTREACHED */
  68                 printk(KERN_ERR "%s: unknown event\n", __func__);
  69                 return -1;
  70         }
  71
  72         return 0;
  73 }
  74
  75 static void event_handler_loop(struct usbip_task *ut)
  76 {
  77         struct usbip_device *ud = container_of(ut, struct usbip_device, eh);
  78
  79         while (1) {
  80                 if (signal_pending(current)) {
  81                         usbip_dbg_eh("signal catched!\n");
  82                         break;
  83                 }
  84
  85                 if (event_handler(ud) < 0)
  86                         break;
  87
  88                 wait_event_interruptible(ud->eh_waitq,
  89                                         usbip_event_happened(ud));
  90                 usbip_dbg_eh("wakeup\n");
  91         }
  92 }
  93
  94 int usbip_start_eh(struct usbip_device *ud)
  95 {
  96         struct usbip_task *eh = &ud->eh;
  97         struct task_struct *th;
  98
  99         init_waitqueue_head(&ud->eh_waitq);
 100         ud->event = 0;
 101
 102         usbip_task_init(eh, "usbip_eh", event_handler_loop);
 103
 104         th = kthread_run(usbip_thread, (void *)eh, "usbip");
 105         if (IS_ERR(th)) {
 106                 printk(KERN_WARNING
 107                         "Unable to start control thread\n");
 108                 return PTR_ERR(th);
 109         }
 110
 111         wait_for_completion(&eh->thread_done);
 112         return 0;
 113 }
 114 EXPORT_SYMBOL_GPL(usbip_start_eh);
 115
 116 void usbip_stop_eh(struct usbip_device *ud)
 117 {
 118         struct usbip_task *eh = &ud->eh;
 119
 120         if (eh->thread == current)
 121                 return; /* do not wait for myself */
 122
 123         wait_for_completion(&eh->thread_done);
 124         usbip_dbg_eh("usbip_eh has finished\n");
 125 }
 126 EXPORT_SYMBOL_GPL(usbip_stop_eh);
 127
 128 void usbip_event_add(struct usbip_device *ud, unsigned long event)
 129 {
 130         spin_lock(&ud->lock);
 131
 132         ud->event |= event;
 133
 134         wake_up(&ud->eh_waitq);
 135
 136         spin_unlock(&ud->lock);
 137 }
 138 EXPORT_SYMBOL_GPL(usbip_event_add);
 139
 140 int usbip_event_happened(struct usbip_device *ud)
 141 {
 142         int happened = 0;
 143
 144         spin_lock(&ud->lock);
 145
 146         if (ud->event != 0)
 147                 happened = 1;
 148
 149         spin_unlock(&ud->lock);
 150
 151         return happened;
 152 }
 153 EXPORT_SYMBOL_GPL(usbip_event_happened);