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 if (val) 61 blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q); 62 else 63 blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q); 64 } 65 66 return count; 67 } 68 69 #endif /* CONFIG_FAIL_IO_TIMEOUT */ 70 71 /** 72 * blk_abort_request -- Request request recovery for the specified command 73 * @req: pointer to the request of interest 74 * 75 * This function requests that the block layer start recovery for the 76 * request by deleting the timer and calling the q's timeout function. 77 * LLDDs who implement their own error recovery MAY ignore the timeout 78 * event if they generated blk_abort_request. 79 */ 80 void blk_abort_request(struct request *req) 81 { 82 /* 83 * All we need to ensure is that timeout scan takes place 84 * immediately and that scan sees the new timeout value. 85 * No need for fancy synchronizations. 86 */ 87 WRITE_ONCE(req->deadline, jiffies); 88 kblockd_schedule_work(&req->q->timeout_work); 89 } 90 EXPORT_SYMBOL_GPL(blk_abort_request); 91 92 unsigned long blk_rq_timeout(unsigned long timeout) 93 { 94 unsigned long maxt; 95 96 maxt = round_jiffies_up(jiffies + BLK_MAX_TIMEOUT); 97 if (time_after(timeout, maxt)) 98 timeout = maxt; 99 100 return timeout; 101 } 102 103 /** 104 * blk_add_timer - Start timeout timer for a single request 105 * @req: request that is about to start running. 106 * 107 * Notes: 108 * Each request has its own timer, and as it is added to the queue, we 109 * set up the timer. When the request completes, we cancel the timer. 110 */ 111 void blk_add_timer(struct request *req) 112 { 113 struct request_queue *q = req->q; 114 unsigned long expiry; 115 116 /* 117 * Some LLDs, like scsi, peek at the timeout to prevent a 118 * command from being retried forever. 119 */ 120 if (!req->timeout) 121 req->timeout = q->rq_timeout; 122 123 req->rq_flags &= ~RQF_TIMED_OUT; 124 125 expiry = jiffies + req->timeout; 126 WRITE_ONCE(req->deadline, expiry); 127 128 /* 129 * If the timer isn't already pending or this timeout is earlier 130 * than an existing one, modify the timer. Round up to next nearest 131 * second. 132 */ 133 expiry = blk_rq_timeout(round_jiffies_up(expiry)); 134 135 if (!timer_pending(&q->timeout) || 136 time_before(expiry, q->timeout.expires)) { 137 unsigned long diff = q->timeout.expires - expiry; 138 139 /* 140 * Due to added timer slack to group timers, the timer 141 * will often be a little in front of what we asked for. 142 * So apply some tolerance here too, otherwise we keep 143 * modifying the timer because expires for value X 144 * will be X + something. 145 */ 146 if (!timer_pending(&q->timeout) || (diff >= HZ / 2)) 147 mod_timer(&q->timeout, expiry); 148 } 149 150 } 151