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