drivers/usb/usbip/usbip_event.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2003-2008 Takahiro Hirofuchi
   4  * Copyright (C) 2015 Nobuo Iwata
   5  */
   6
   7 #include <linux/kthread.h>
   8 #include <linux/export.h>
   9 #include <linux/slab.h>
  10 #include <linux/workqueue.h>
  11
  12 #include "usbip_common.h"
  13
  14 struct usbip_event {
  15         struct list_head node;
  16         struct usbip_device *ud;
  17 };
  18
  19 static DEFINE_SPINLOCK(event_lock);
  20 static LIST_HEAD(event_list);
  21
  22 static void set_event(struct usbip_device *ud, unsigned long event)
  23 {
  24         unsigned long flags;
  25
  26         spin_lock_irqsave(&ud->lock, flags);
  27         ud->event |= event;
  28         spin_unlock_irqrestore(&ud->lock, flags);
  29 }
  30
  31 static void unset_event(struct usbip_device *ud, unsigned long event)
  32 {
  33         unsigned long flags;
  34
  35         spin_lock_irqsave(&ud->lock, flags);
  36         ud->event &= ~event;
  37         spin_unlock_irqrestore(&ud->lock, flags);
  38 }
  39
  40 static struct usbip_device *get_event(void)
  41 {
  42         struct usbip_event *ue = NULL;
  43         struct usbip_device *ud = NULL;
  44         unsigned long flags;
  45
  46         spin_lock_irqsave(&event_lock, flags);
  47         if (!list_empty(&event_list)) {
  48                 ue = list_first_entry(&event_list, struct usbip_event, node);
  49                 list_del(&ue->node);
  50         }
  51         spin_unlock_irqrestore(&event_lock, flags);
  52
  53         if (ue) {
  54                 ud = ue->ud;
  55                 kfree(ue);
  56         }
  57         return ud;
  58 }
  59
  60 static struct task_struct *worker_context;
  61
  62 static void event_handler(struct work_struct *work)
  63 {
  64         struct usbip_device *ud;
  65
  66         if (worker_context == NULL) {
  67                 worker_context = current;
  68         }
  69
  70         while ((ud = get_event()) != NULL) {
  71                 usbip_dbg_eh("pending event %lx\n", ud->event);
  72
  73                 /*
  74                  * NOTE: shutdown must come first.
  75                  * Shutdown the device.
  76                  */
  77                 if (ud->event & USBIP_EH_SHUTDOWN) {
  78                         ud->eh_ops.shutdown(ud);
  79                         unset_event(ud, USBIP_EH_SHUTDOWN);
  80                 }
  81
  82                 /* Reset the device. */
  83                 if (ud->event & USBIP_EH_RESET) {
  84                         ud->eh_ops.reset(ud);
  85                         unset_event(ud, USBIP_EH_RESET);
  86                 }
  87
  88                 /* Mark the device as unusable. */
  89                 if (ud->event & USBIP_EH_UNUSABLE) {
  90                         ud->eh_ops.unusable(ud);
  91                         unset_event(ud, USBIP_EH_UNUSABLE);
  92                 }
  93
  94                 /* Stop the error handler. */
  95                 if (ud->event & USBIP_EH_BYE)
  96                         usbip_dbg_eh("removed %p\n", ud);
  97
  98                 wake_up(&ud->eh_waitq);
  99         }
 100 }
 101
 102 int usbip_start_eh(struct usbip_device *ud)
 103 {
 104         init_waitqueue_head(&ud->eh_waitq);
 105         ud->event = 0;
 106         return 0;
 107 }
 108 EXPORT_SYMBOL_GPL(usbip_start_eh);
 109
 110 void usbip_stop_eh(struct usbip_device *ud)
 111 {
 112         unsigned long pending = ud->event & ~USBIP_EH_BYE;
 113
 114         if (!(ud->event & USBIP_EH_BYE))
 115                 usbip_dbg_eh("usbip_eh stopping but not removed\n");
 116
 117         if (pending)
 118                 usbip_dbg_eh("usbip_eh waiting completion %lx\n", pending);
 119
 120         wait_event_interruptible(ud->eh_waitq, !(ud->event & ~USBIP_EH_BYE));
 121         usbip_dbg_eh("usbip_eh has stopped\n");
 122 }
 123 EXPORT_SYMBOL_GPL(usbip_stop_eh);
 124
 125 #define WORK_QUEUE_NAME "usbip_event"
 126
 127 static struct workqueue_struct *usbip_queue;
 128 static DECLARE_WORK(usbip_work, event_handler);
 129
 130 int usbip_init_eh(void)
 131 {
 132         usbip_queue = create_singlethread_workqueue(WORK_QUEUE_NAME);
 133         if (usbip_queue == NULL) {
 134                 pr_err("failed to create usbip_event\n");
 135                 return -ENOMEM;
 136         }
 137         return 0;
 138 }
 139
 140 void usbip_finish_eh(void)
 141 {
 142         flush_workqueue(usbip_queue);
 143         destroy_workqueue(usbip_queue);
 144         usbip_queue = NULL;
 145 }
 146
 147 void usbip_event_add(struct usbip_device *ud, unsigned long event)
 148 {
 149         struct usbip_event *ue;
 150         unsigned long flags;
 151
 152         if (ud->event & USBIP_EH_BYE)
 153                 return;
 154
 155         set_event(ud, event);
 156
 157         spin_lock_irqsave(&event_lock, flags);
 158
 159         list_for_each_entry_reverse(ue, &event_list, node) {
 160                 if (ue->ud == ud)
 161                         goto out;
 162         }
 163
 164         ue = kmalloc(sizeof(struct usbip_event), GFP_ATOMIC);
 165         if (ue == NULL)
 166                 goto out;
 167
 168         ue->ud = ud;
 169
 170         list_add_tail(&ue->node, &event_list);
 171         queue_work(usbip_queue, &usbip_work);
 172
 173 out:
 174         spin_unlock_irqrestore(&event_lock, flags);
 175 }
 176 EXPORT_SYMBOL_GPL(usbip_event_add);
 177
 178 int usbip_event_happened(struct usbip_device *ud)
 179 {
 180         int happened = 0;
 181         unsigned long flags;
 182
 183         spin_lock_irqsave(&ud->lock, flags);
 184         if (ud->event != 0)
 185                 happened = 1;
 186         spin_unlock_irqrestore(&ud->lock, flags);
 187
 188         return happened;
 189 }
 190 EXPORT_SYMBOL_GPL(usbip_event_happened);
 191
 192 int usbip_in_eh(struct task_struct *task)
 193 {
 194         if (task == worker_context)
 195                 return 1;
 196
 197         return 0;
 198 }
 199 EXPORT_SYMBOL_GPL(usbip_in_eh);