1 /* 2 * Functions related to generic timeout handling of requests. 3 */ 4 #include <linux/kernel.h> 5 #include <linux/module.h> 6 #include <linux/blkdev.h> 7 #include <linux/fault-inject.h> 8 9 #include "blk.h" 10 11 #ifdef CONFIG_FAIL_IO_TIMEOUT 12 13 static DECLARE_FAULT_ATTR(fail_io_timeout); 14 15 static int __init setup_fail_io_timeout(char *str) 16 { 17 return setup_fault_attr(&fail_io_timeout, str); 18 } 19 __setup("fail_io_timeout=", setup_fail_io_timeout); 20 21 int blk_should_fake_timeout(struct request_queue *q) 22 { 23 if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags)) 24 return 0; 25 26 return should_fail(&fail_io_timeout, 1); 27 } 28 29 static int __init fail_io_timeout_debugfs(void) 30 { 31 return init_fault_attr_dentries(&fail_io_timeout, "fail_io_timeout"); 32 } 33 34 late_initcall(fail_io_timeout_debugfs); 35 36 ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr, 37 char *buf) 38 { 39 struct gendisk *disk = dev_to_disk(dev); 40 int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags); 41 42 return sprintf(buf, "%d\n", set != 0); 43 } 44 45 ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr, 46 const char *buf, size_t count) 47 { 48 struct gendisk *disk = dev_to_disk(dev); 49 int val; 50 51 if (count) { 52 struct request_queue *q = disk->queue; 53 char *p = (char *) buf; 54 55 val = simple_strtoul(p, &p, 10); 56 spin_lock_irq(q->queue_lock); 57 if (val) 58 queue_flag_set(QUEUE_FLAG_FAIL_IO, q); 59 else 60 queue_flag_clear(QUEUE_FLAG_FAIL_IO, q); 61 spin_unlock_irq(q->queue_lock); 62 } 63 64 return count; 65 } 66 67 #endif /* CONFIG_FAIL_IO_TIMEOUT */ 68 69 /* 70 * blk_delete_timer - Delete/cancel timer for a given function. 71 * @req: request that we are canceling timer for 72 * 73 */ 74 void blk_delete_timer(struct request *req) 75 { 76 list_del_init(&req->timeout_list); 77 } 78 79 static void blk_rq_timed_out(struct request *req) 80 { 81 struct request_queue *q = req->q; 82 enum blk_eh_timer_return ret; 83 84 ret = q->rq_timed_out_fn(req); 85 switch (ret) { 86 case BLK_EH_HANDLED: 87 __blk_complete_request(req); 88 break; 89 case BLK_EH_RESET_TIMER: 90 blk_clear_rq_complete(req); 91 blk_add_timer(req); 92 break; 93 case BLK_EH_NOT_HANDLED: 94 /* 95 * LLD handles this for now but in the future 96 * we can send a request msg to abort the command 97 * and we can move more of the generic scsi eh code to 98 * the blk layer. 99 */ 100 break; 101 default: 102 printk(KERN_ERR "block: bad eh return: %d\n", ret); 103 break; 104 } 105 } 106 107 void blk_rq_timed_out_timer(unsigned long data) 108 { 109 struct request_queue *q = (struct request_queue *) data; 110 unsigned long flags, next = 0; 111 struct request *rq, *tmp; 112 113 spin_lock_irqsave(q->queue_lock, flags); 114 115 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) { 116 if (time_after_eq(jiffies, rq->deadline)) { 117 list_del_init(&rq->timeout_list); 118 119 /* 120 * Check if we raced with end io completion 121 */ 122 if (blk_mark_rq_complete(rq)) 123 continue; 124 blk_rq_timed_out(rq); 125 } else { 126 if (!next || time_after(next, rq->deadline)) 127 next = rq->deadline; 128 } 129 } 130 131 /* 132 * next can never be 0 here with the list non-empty, since we always 133 * bump ->deadline to 1 so we can detect if the timer was ever added 134 * or not. See comment in blk_add_timer() 135 */ 136 if (next) 137 mod_timer(&q->timeout, round_jiffies_up(next)); 138 139 spin_unlock_irqrestore(q->queue_lock, flags); 140 } 141 142 /** 143 * blk_abort_request -- Request request recovery for the specified command 144 * @req: pointer to the request of interest 145 * 146 * This function requests that the block layer start recovery for the 147 * request by deleting the timer and calling the q's timeout function. 148 * LLDDs who implement their own error recovery MAY ignore the timeout 149 * event if they generated blk_abort_req. Must hold queue lock. 150 */ 151 void blk_abort_request(struct request *req) 152 { 153 if (blk_mark_rq_complete(req)) 154 return; 155 blk_delete_timer(req); 156 blk_rq_timed_out(req); 157 } 158 EXPORT_SYMBOL_GPL(blk_abort_request); 159 160 /** 161 * blk_add_timer - Start timeout timer for a single request 162 * @req: request that is about to start running. 163 * 164 * Notes: 165 * Each request has its own timer, and as it is added to the queue, we 166 * set up the timer. When the request completes, we cancel the timer. 167 */ 168 void blk_add_timer(struct request *req) 169 { 170 struct request_queue *q = req->q; 171 unsigned long expiry; 172 173 if (!q->rq_timed_out_fn) 174 return; 175 176 BUG_ON(!list_empty(&req->timeout_list)); 177 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags)); 178 179 if (req->timeout) 180 req->deadline = jiffies + req->timeout; 181 else { 182 req->deadline = jiffies + q->rq_timeout; 183 /* 184 * Some LLDs, like scsi, peek at the timeout to prevent 185 * a command from being retried forever. 186 */ 187 req->timeout = q->rq_timeout; 188 } 189 list_add_tail(&req->timeout_list, &q->timeout_list); 190 191 /* 192 * If the timer isn't already pending or this timeout is earlier 193 * than an existing one, modify the timer. Round up to next nearest 194 * second. 195 */ 196 expiry = round_jiffies_up(req->deadline); 197 198 if (!timer_pending(&q->timeout) || 199 time_before(expiry, q->timeout.expires)) 200 mod_timer(&q->timeout, expiry); 201 } 202 203 /** 204 * blk_abort_queue -- Abort all request on given queue 205 * @queue: pointer to queue 206 * 207 */ 208 void blk_abort_queue(struct request_queue *q) 209 { 210 unsigned long flags; 211 struct request *rq, *tmp; 212 LIST_HEAD(list); 213 214 spin_lock_irqsave(q->queue_lock, flags); 215 216 elv_abort_queue(q); 217 218 /* 219 * Splice entries to local list, to avoid deadlocking if entries 220 * get readded to the timeout list by error handling 221 */ 222 list_splice_init(&q->timeout_list, &list); 223 224 list_for_each_entry_safe(rq, tmp, &list, timeout_list) 225 blk_abort_request(rq); 226 227 spin_unlock_irqrestore(q->queue_lock, flags); 228 229 } 230 EXPORT_SYMBOL_GPL(blk_abort_queue); 231