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 #include "blk-mq.h" 11 12 #ifdef CONFIG_FAIL_IO_TIMEOUT 13 14 static DECLARE_FAULT_ATTR(fail_io_timeout); 15 16 static int __init setup_fail_io_timeout(char *str) 17 { 18 return setup_fault_attr(&fail_io_timeout, str); 19 } 20 __setup("fail_io_timeout=", setup_fail_io_timeout); 21 22 int blk_should_fake_timeout(struct request_queue *q) 23 { 24 if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags)) 25 return 0; 26 27 return should_fail(&fail_io_timeout, 1); 28 } 29 30 static int __init fail_io_timeout_debugfs(void) 31 { 32 struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout", 33 NULL, &fail_io_timeout); 34 35 return PTR_ERR_OR_ZERO(dir); 36 } 37 38 late_initcall(fail_io_timeout_debugfs); 39 40 ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr, 41 char *buf) 42 { 43 struct gendisk *disk = dev_to_disk(dev); 44 int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags); 45 46 return sprintf(buf, "%d\n", set != 0); 47 } 48 49 ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr, 50 const char *buf, size_t count) 51 { 52 struct gendisk *disk = dev_to_disk(dev); 53 int val; 54 55 if (count) { 56 struct request_queue *q = disk->queue; 57 char *p = (char *) buf; 58 59 val = simple_strtoul(p, &p, 10); 60 spin_lock_irq(q->queue_lock); 61 if (val) 62 queue_flag_set(QUEUE_FLAG_FAIL_IO, q); 63 else 64 queue_flag_clear(QUEUE_FLAG_FAIL_IO, q); 65 spin_unlock_irq(q->queue_lock); 66 } 67 68 return count; 69 } 70 71 #endif /* CONFIG_FAIL_IO_TIMEOUT */ 72 73 /* 74 * blk_delete_timer - Delete/cancel timer for a given function. 75 * @req: request that we are canceling timer for 76 * 77 */ 78 void blk_delete_timer(struct request *req) 79 { 80 list_del_init(&req->timeout_list); 81 } 82 83 static void blk_rq_timed_out(struct request *req) 84 { 85 struct request_queue *q = req->q; 86 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER; 87 88 if (q->rq_timed_out_fn) 89 ret = q->rq_timed_out_fn(req); 90 switch (ret) { 91 case BLK_EH_HANDLED: 92 /* Can we use req->errors here? */ 93 if (q->mq_ops) 94 blk_mq_complete_request(req, req->errors); 95 else 96 __blk_complete_request(req); 97 break; 98 case BLK_EH_RESET_TIMER: 99 if (q->mq_ops) 100 blk_mq_add_timer(req); 101 else 102 blk_add_timer(req); 103 104 blk_clear_rq_complete(req); 105 break; 106 case BLK_EH_NOT_HANDLED: 107 /* 108 * LLD handles this for now but in the future 109 * we can send a request msg to abort the command 110 * and we can move more of the generic scsi eh code to 111 * the blk layer. 112 */ 113 break; 114 default: 115 printk(KERN_ERR "block: bad eh return: %d\n", ret); 116 break; 117 } 118 } 119 120 void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout, 121 unsigned int *next_set) 122 { 123 if (time_after_eq(jiffies, rq->deadline)) { 124 list_del_init(&rq->timeout_list); 125 126 /* 127 * Check if we raced with end io completion 128 */ 129 if (!blk_mark_rq_complete(rq)) 130 blk_rq_timed_out(rq); 131 } else if (!*next_set || time_after(*next_timeout, rq->deadline)) { 132 *next_timeout = rq->deadline; 133 *next_set = 1; 134 } 135 } 136 137 void blk_rq_timed_out_timer(unsigned long data) 138 { 139 struct request_queue *q = (struct request_queue *) data; 140 unsigned long flags, next = 0; 141 struct request *rq, *tmp; 142 int next_set = 0; 143 144 spin_lock_irqsave(q->queue_lock, flags); 145 146 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) 147 blk_rq_check_expired(rq, &next, &next_set); 148 149 if (next_set) 150 mod_timer(&q->timeout, round_jiffies_up(next)); 151 152 spin_unlock_irqrestore(q->queue_lock, flags); 153 } 154 155 /** 156 * blk_abort_request -- Request request recovery for the specified command 157 * @req: pointer to the request of interest 158 * 159 * This function requests that the block layer start recovery for the 160 * request by deleting the timer and calling the q's timeout function. 161 * LLDDs who implement their own error recovery MAY ignore the timeout 162 * event if they generated blk_abort_req. Must hold queue lock. 163 */ 164 void blk_abort_request(struct request *req) 165 { 166 if (blk_mark_rq_complete(req)) 167 return; 168 blk_delete_timer(req); 169 blk_rq_timed_out(req); 170 } 171 EXPORT_SYMBOL_GPL(blk_abort_request); 172 173 void __blk_add_timer(struct request *req, struct list_head *timeout_list) 174 { 175 struct request_queue *q = req->q; 176 unsigned long expiry; 177 178 if (!q->rq_timed_out_fn) 179 return; 180 181 BUG_ON(!list_empty(&req->timeout_list)); 182 183 /* 184 * Some LLDs, like scsi, peek at the timeout to prevent a 185 * command from being retried forever. 186 */ 187 if (!req->timeout) 188 req->timeout = q->rq_timeout; 189 190 req->deadline = jiffies + req->timeout; 191 if (timeout_list) 192 list_add_tail(&req->timeout_list, timeout_list); 193 194 /* 195 * If the timer isn't already pending or this timeout is earlier 196 * than an existing one, modify the timer. Round up to next nearest 197 * second. 198 */ 199 expiry = round_jiffies_up(req->deadline); 200 201 if (!timer_pending(&q->timeout) || 202 time_before(expiry, q->timeout.expires)) 203 mod_timer(&q->timeout, expiry); 204 205 } 206 207 /** 208 * blk_add_timer - Start timeout timer for a single request 209 * @req: request that is about to start running. 210 * 211 * Notes: 212 * Each request has its own timer, and as it is added to the queue, we 213 * set up the timer. When the request completes, we cancel the timer. 214 */ 215 void blk_add_timer(struct request *req) 216 { 217 __blk_add_timer(req, &req->q->timeout_list); 218 } 219 220