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 25 static 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 64 static 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 81 int 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_warn("Unable to start control thread\n"); 89 return PTR_ERR(ud->eh); 90 } 91 92 return 0; 93 } 94 EXPORT_SYMBOL_GPL(usbip_start_eh); 95 96 void 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 } 104 EXPORT_SYMBOL_GPL(usbip_stop_eh); 105 106 void usbip_event_add(struct usbip_device *ud, unsigned long event) 107 { 108 unsigned long flags; 109 110 spin_lock_irqsave(&ud->lock, flags); 111 ud->event |= event; 112 wake_up(&ud->eh_waitq); 113 spin_unlock_irqrestore(&ud->lock, flags); 114 } 115 EXPORT_SYMBOL_GPL(usbip_event_add); 116 117 int usbip_event_happened(struct usbip_device *ud) 118 { 119 int happened = 0; 120 121 spin_lock(&ud->lock); 122 if (ud->event != 0) 123 happened = 1; 124 spin_unlock(&ud->lock); 125 126 return happened; 127 } 128 EXPORT_SYMBOL_GPL(usbip_event_happened); 129