1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Functions related to generic timeout handling of requests. 4 */ 5 #include <linux/kernel.h> 6 #include <linux/module.h> 7 #include <linux/blkdev.h> 8 #include <linux/fault-inject.h> 9 10 #include "blk.h" 11 #include "blk-mq.h" 12 13 #ifdef CONFIG_FAIL_IO_TIMEOUT 14 15 static DECLARE_FAULT_ATTR(fail_io_timeout); 16 17 static int __init setup_fail_io_timeout(char *str) 18 { 19 return setup_fault_attr(&fail_io_timeout, str); 20 } 21 __setup("fail_io_timeout=", setup_fail_io_timeout); 22 23 int blk_should_fake_timeout(struct request_queue *q) 24 { 25 if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags)) 26 return 0; 27 28 return should_fail(&fail_io_timeout, 1); 29 } 30 31 static int __init fail_io_timeout_debugfs(void) 32 { 33 struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout", 34 NULL, &fail_io_timeout); 35 36 return PTR_ERR_OR_ZERO(dir); 37 } 38 39 late_initcall(fail_io_timeout_debugfs); 40 41 ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr, 42 char *buf) 43 { 44 struct gendisk *disk = dev_to_disk(dev); 45 int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags); 46 47 return sprintf(buf, "%d\n", set != 0); 48 } 49 50 ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr, 51 const char *buf, size_t count) 52 { 53 struct gendisk *disk = dev_to_disk(dev); 54 int val; 55 56 if (count) { 57 struct request_queue *q = disk->queue; 58 char *p = (char *) buf; 59 60 val = simple_strtoul(p, &p, 10); 61 if (val) 62 blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q); 63 else 64 blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q); 65 } 66 67 return count; 68 } 69 70 #endif /* CONFIG_FAIL_IO_TIMEOUT */ 71 72 /** 73 * blk_abort_request -- Request request recovery for the specified command 74 * @req: pointer to the request of interest 75 * 76 * This function requests that the block layer start recovery for the 77 * request by deleting the timer and calling the q's timeout function. 78 * LLDDs who implement their own error recovery MAY ignore the timeout 79 * event if they generated blk_abort_request. 80 */ 81 void blk_abort_request(struct request *req) 82 { 83 /* 84 * All we need to ensure is that timeout scan takes place 85 * immediately and that scan sees the new timeout value. 86 * No need for fancy synchronizations. 87 */ 88 WRITE_ONCE(req->deadline, jiffies); 89 kblockd_schedule_work(&req->q->timeout_work); 90 } 91 EXPORT_SYMBOL_GPL(blk_abort_request); 92 93 unsigned long blk_rq_timeout(unsigned long timeout) 94 { 95 unsigned long maxt; 96 97 maxt = round_jiffies_up(jiffies + BLK_MAX_TIMEOUT); 98 if (time_after(timeout, maxt)) 99 timeout = maxt; 100 101 return timeout; 102 } 103 104 /** 105 * blk_add_timer - Start timeout timer for a single request 106 * @req: request that is about to start running. 107 * 108 * Notes: 109 * Each request has its own timer, and as it is added to the queue, we 110 * set up the timer. When the request completes, we cancel the timer. 111 */ 112 void blk_add_timer(struct request *req) 113 { 114 struct request_queue *q = req->q; 115 unsigned long expiry; 116 117 /* 118 * Some LLDs, like scsi, peek at the timeout to prevent a 119 * command from being retried forever. 120 */ 121 if (!req->timeout) 122 req->timeout = q->rq_timeout; 123 124 req->rq_flags &= ~RQF_TIMED_OUT; 125 126 expiry = jiffies + req->timeout; 127 WRITE_ONCE(req->deadline, expiry); 128 129 /* 130 * If the timer isn't already pending or this timeout is earlier 131 * than an existing one, modify the timer. Round up to next nearest 132 * second. 133 */ 134 expiry = blk_rq_timeout(round_jiffies_up(expiry)); 135 136 if (!timer_pending(&q->timeout) || 137 time_before(expiry, q->timeout.expires)) { 138 unsigned long diff = q->timeout.expires - expiry; 139 140 /* 141 * Due to added timer slack to group timers, the timer 142 * will often be a little in front of what we asked for. 143 * So apply some tolerance here too, otherwise we keep 144 * modifying the timer because expires for value X 145 * will be X + something. 146 */ 147 if (!timer_pending(&q->timeout) || (diff >= HZ / 2)) 148 mod_timer(&q->timeout, expiry); 149 } 150 151 } 152