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
  43                 /* Reset the device. */
  44                 if (ud->event & USBIP_EH_RESET) {
  45                         ud->eh_ops.reset(ud);
  46
  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
  54                         ud->event &= ~USBIP_EH_UNUSABLE;
  55                 }
  56
  57                 /* Stop the error handler. */
  58                 if (ud->event & USBIP_EH_BYE)
  59                         return -1;
  60         }
  61
  62         return 0;
  63 }
  64
  65 static void event_handler_loop(struct usbip_task *ut)
  66 {
  67         struct usbip_device *ud = container_of(ut, struct usbip_device, eh);
  68
  69         while (1) {
  70                 if (signal_pending(current)) {
  71                         usbip_dbg_eh("signal catched!\n");
  72                         break;
  73                 }
  74
  75                 if (event_handler(ud) < 0)
  76                         break;
  77
  78                 wait_event_interruptible(ud->eh_waitq,
  79                                         usbip_event_happened(ud));
  80                 usbip_dbg_eh("wakeup\n");
  81         }
  82 }
  83
  84 int usbip_start_eh(struct usbip_device *ud)
  85 {
  86         struct usbip_task *eh = &ud->eh;
  87         struct task_struct *th;
  88
  89         init_waitqueue_head(&ud->eh_waitq);
  90         ud->event = 0;
  91
  92         usbip_task_init(eh, "usbip_eh", event_handler_loop);
  93
  94         th = kthread_run(usbip_thread, (void *)eh, "usbip");
  95         if (IS_ERR(th)) {
  96                 printk(KERN_WARNING
  97                         "Unable to start control thread\n");
  98                 return PTR_ERR(th);
  99         }
 100
 101         wait_for_completion(&eh->thread_done);
 102         return 0;
 103 }
 104 EXPORT_SYMBOL_GPL(usbip_start_eh);
 105
 106 void usbip_stop_eh(struct usbip_device *ud)
 107 {
 108         struct usbip_task *eh = &ud->eh;
 109
 110         if (eh->thread == current)
 111                 return; /* do not wait for myself */
 112
 113         wait_for_completion(&eh->thread_done);
 114         usbip_dbg_eh("usbip_eh has finished\n");
 115 }
 116 EXPORT_SYMBOL_GPL(usbip_stop_eh);
 117
 118 void usbip_event_add(struct usbip_device *ud, unsigned long event)
 119 {
 120         spin_lock(&ud->lock);
 121
 122         ud->event |= event;
 123
 124         wake_up(&ud->eh_waitq);
 125
 126         spin_unlock(&ud->lock);
 127 }
 128 EXPORT_SYMBOL_GPL(usbip_event_add);
 129
 130 int usbip_event_happened(struct usbip_device *ud)
 131 {
 132         int happened = 0;
 133
 134         spin_lock(&ud->lock);
 135
 136         if (ud->event != 0)
 137                 happened = 1;
 138
 139         spin_unlock(&ud->lock);
 140
 141         return happened;
 142 }
 143 EXPORT_SYMBOL_GPL(usbip_event_happened);