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 mutex_lock(&ud->sysfs_lock); 74 /* 75 * NOTE: shutdown must come first. 76 * Shutdown the device. 77 */ 78 if (ud->event & USBIP_EH_SHUTDOWN) { 79 ud->eh_ops.shutdown(ud); 80 unset_event(ud, USBIP_EH_SHUTDOWN); 81 } 82 83 /* Reset the device. */ 84 if (ud->event & USBIP_EH_RESET) { 85 ud->eh_ops.reset(ud); 86 unset_event(ud, USBIP_EH_RESET); 87 } 88 89 /* Mark the device as unusable. */ 90 if (ud->event & USBIP_EH_UNUSABLE) { 91 ud->eh_ops.unusable(ud); 92 unset_event(ud, USBIP_EH_UNUSABLE); 93 } 94 mutex_unlock(&ud->sysfs_lock); 95 96 wake_up(&ud->eh_waitq); 97 } 98 } 99 100 int usbip_start_eh(struct usbip_device *ud) 101 { 102 init_waitqueue_head(&ud->eh_waitq); 103 ud->event = 0; 104 return 0; 105 } 106 EXPORT_SYMBOL_GPL(usbip_start_eh); 107 108 void usbip_stop_eh(struct usbip_device *ud) 109 { 110 unsigned long pending = ud->event & ~USBIP_EH_BYE; 111 112 if (!(ud->event & USBIP_EH_BYE)) 113 usbip_dbg_eh("usbip_eh stopping but not removed\n"); 114 115 if (pending) 116 usbip_dbg_eh("usbip_eh waiting completion %lx\n", pending); 117 118 wait_event_interruptible(ud->eh_waitq, !(ud->event & ~USBIP_EH_BYE)); 119 usbip_dbg_eh("usbip_eh has stopped\n"); 120 } 121 EXPORT_SYMBOL_GPL(usbip_stop_eh); 122 123 #define WORK_QUEUE_NAME "usbip_event" 124 125 static struct workqueue_struct *usbip_queue; 126 static DECLARE_WORK(usbip_work, event_handler); 127 128 int usbip_init_eh(void) 129 { 130 usbip_queue = create_singlethread_workqueue(WORK_QUEUE_NAME); 131 if (usbip_queue == NULL) { 132 pr_err("failed to create usbip_event\n"); 133 return -ENOMEM; 134 } 135 return 0; 136 } 137 138 void usbip_finish_eh(void) 139 { 140 destroy_workqueue(usbip_queue); 141 usbip_queue = NULL; 142 } 143 144 void usbip_event_add(struct usbip_device *ud, unsigned long event) 145 { 146 struct usbip_event *ue; 147 unsigned long flags; 148 149 if (ud->event & USBIP_EH_BYE) 150 return; 151 152 set_event(ud, event); 153 154 spin_lock_irqsave(&event_lock, flags); 155 156 list_for_each_entry_reverse(ue, &event_list, node) { 157 if (ue->ud == ud) 158 goto out; 159 } 160 161 ue = kmalloc(sizeof(struct usbip_event), GFP_ATOMIC); 162 if (ue == NULL) 163 goto out; 164 165 ue->ud = ud; 166 167 list_add_tail(&ue->node, &event_list); 168 queue_work(usbip_queue, &usbip_work); 169 170 out: 171 spin_unlock_irqrestore(&event_lock, flags); 172 } 173 EXPORT_SYMBOL_GPL(usbip_event_add); 174 175 int usbip_event_happened(struct usbip_device *ud) 176 { 177 int happened = 0; 178 unsigned long flags; 179 180 spin_lock_irqsave(&ud->lock, flags); 181 if (ud->event != 0) 182 happened = 1; 183 spin_unlock_irqrestore(&ud->lock, flags); 184 185 return happened; 186 } 187 EXPORT_SYMBOL_GPL(usbip_event_happened); 188 189 int usbip_in_eh(struct task_struct *task) 190 { 191 if (task == worker_context) 192 return 1; 193 194 return 0; 195 } 196 EXPORT_SYMBOL_GPL(usbip_in_eh); 197