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 <linux/kthread.h>
  21 #include <linux/export.h>
  22
  23 #include "usbip_common.h"
  24
  25 static int event_handler(struct usbip_device *ud)
  26 {
  27         usbip_dbg_eh("enter\n");
  28
  29         /*
  30          * Events are handled by only this thread.
  31          */
  32         while (usbip_event_happened(ud)) {
  33                 usbip_dbg_eh("pending event %lx\n", ud->event);
  34
  35                 /*
  36                  * NOTE: shutdown must come first.
  37                  * Shutdown the device.
  38                  */
  39                 if (ud->event & USBIP_EH_SHUTDOWN) {
  40                         ud->eh_ops.shutdown(ud);
  41                         ud->event &= ~USBIP_EH_SHUTDOWN;
  42                 }
  43
  44                 /* Reset the device. */
  45                 if (ud->event & USBIP_EH_RESET) {
  46                         ud->eh_ops.reset(ud);
  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                         ud->event &= ~USBIP_EH_UNUSABLE;
  54                 }
  55
  56                 /* Stop the error handler. */
  57                 if (ud->event & USBIP_EH_BYE)
  58                         return -1;
  59         }
  60
  61         return 0;
  62 }
  63
  64 static int event_handler_loop(void *data)
  65 {
  66         struct usbip_device *ud = data;
  67
  68         while (!kthread_should_stop()) {
  69                 wait_event_interruptible(ud->eh_waitq,
  70                                          usbip_event_happened(ud) ||
  71                                          kthread_should_stop());
  72                 usbip_dbg_eh("wakeup\n");
  73
  74                 if (event_handler(ud) < 0)
  75                         break;
  76         }
  77
  78         return 0;
  79 }
  80
  81 int usbip_start_eh(struct usbip_device *ud)
  82 {
  83         init_waitqueue_head(&ud->eh_waitq);
  84         ud->event = 0;
  85
  86         ud->eh = kthread_run(event_handler_loop, ud, "usbip_eh");
  87         if (IS_ERR(ud->eh)) {
  88                 pr_warning("Unable to start control thread\n");
  89                 return PTR_ERR(ud->eh);
  90         }
  91
  92         return 0;
  93 }
  94 EXPORT_SYMBOL_GPL(usbip_start_eh);
  95
  96 void usbip_stop_eh(struct usbip_device *ud)
  97 {
  98         if (ud->eh == current)
  99                 return; /* do not wait for myself */
 100
 101         kthread_stop(ud->eh);
 102         usbip_dbg_eh("usbip_eh has finished\n");
 103 }
 104 EXPORT_SYMBOL_GPL(usbip_stop_eh);
 105
 106 void usbip_event_add(struct usbip_device *ud, unsigned long event)
 107 {
 108         spin_lock(&ud->lock);
 109         ud->event |= event;
 110         wake_up(&ud->eh_waitq);
 111         spin_unlock(&ud->lock);
 112 }
 113 EXPORT_SYMBOL_GPL(usbip_event_add);
 114
 115 int usbip_event_happened(struct usbip_device *ud)
 116 {
 117         int happened = 0;
 118
 119         spin_lock(&ud->lock);
 120         if (ud->event != 0)
 121                 happened = 1;
 122         spin_unlock(&ud->lock);
 123
 124         return happened;
 125 }
 126 EXPORT_SYMBOL_GPL(usbip_event_happened);