LXR linux/drivers/staging/usbip/usbip

   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
  25static 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
  64static 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
  81int 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}
  94EXPORT_SYMBOL_GPL(usbip_start_eh);
  95
  96void 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}
 104EXPORT_SYMBOL_GPL(usbip_stop_eh);
 105
 106void 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}
 113EXPORT_SYMBOL_GPL(usbip_event_add);
 114
 115int 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}
 126EXPORT_SYMBOL_GPL(usbip_event_happened);
 127