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); 200