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
  22 #include "usbip_common.h"
  23
  24 static int event_handler(struct usbip_device *ud)
  25 {
  26         usbip_dbg_eh("enter\n");
  27
  28         /*
  29          * Events are handled by only this thread.
  30          */
  31         while (usbip_event_happened(ud)) {
  32                 usbip_dbg_eh("pending event %lx\n", ud->event);
  33
  34                 /*
  35                  * NOTE: shutdown must come first.
  36                  * Shutdown the device.
  37                  */
  38                 if (ud->event & USBIP_EH_SHUTDOWN) {
  39                         ud->eh_ops.shutdown(ud);
  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                         ud->event &= ~USBIP_EH_RESET;
  47                 }
  48
  49                 /* Mark the device as unusable. */
  50                 if (ud->event & USBIP_EH_UNUSABLE) {
  51                         ud->eh_ops.unusable(ud);
  52                         ud->event &= ~USBIP_EH_UNUSABLE;
  53                 }
  54
  55                 /* Stop the error handler. */
  56                 if (ud->event & USBIP_EH_BYE)
  57                         return -1;
  58         }
  59
  60         return 0;
  61 }
  62
  63 static int event_handler_loop(void *data)
  64 {
  65         struct usbip_device *ud = data;
  66
  67         while (!kthread_should_stop()) {
  68                 wait_event_interruptible(ud->eh_waitq,
  69                                          usbip_event_happened(ud) ||
  70                                          kthread_should_stop());
  71                 usbip_dbg_eh("wakeup\n");
  72
  73                 if (event_handler(ud) < 0)
  74                         break;
  75         }
  76
  77         return 0;
  78 }
  79
  80 int usbip_start_eh(struct usbip_device *ud)
  81 {
  82         init_waitqueue_head(&ud->eh_waitq);
  83         ud->event = 0;
  84
  85         ud->eh = kthread_run(event_handler_loop, ud, "usbip_eh");
  86         if (IS_ERR(ud->eh)) {
  87                 pr_warning("Unable to start control thread\n");
  88                 return PTR_ERR(ud->eh);
  89         }
  90
  91         return 0;
  92 }
  93 EXPORT_SYMBOL_GPL(usbip_start_eh);
  94
  95 void usbip_stop_eh(struct usbip_device *ud)
  96 {
  97         if (ud->eh == current)
  98                 return; /* do not wait for myself */
  99
 100         kthread_stop(ud->eh);
 101         usbip_dbg_eh("usbip_eh has finished\n");
 102 }
 103 EXPORT_SYMBOL_GPL(usbip_stop_eh);
 104
 105 void usbip_event_add(struct usbip_device *ud, unsigned long event)
 106 {
 107         spin_lock(&ud->lock);
 108         ud->event |= event;
 109         wake_up(&ud->eh_waitq);
 110         spin_unlock(&ud->lock);
 111 }
 112 EXPORT_SYMBOL_GPL(usbip_event_add);
 113
 114 int usbip_event_happened(struct usbip_device *ud)
 115 {
 116         int happened = 0;
 117
 118         spin_lock(&ud->lock);
 119         if (ud->event != 0)
 120                 happened = 1;
 121         spin_unlock(&ud->lock);
 122
 123         return happened;
 124 }
 125 EXPORT_SYMBOL_GPL(usbip_event_happened);