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 bool __blk_should_fake_timeout(struct request_queue *q) 24 { 25 return should_fail(&fail_io_timeout, 1); 26 } 27 EXPORT_SYMBOL_GPL(__blk_should_fake_timeout); 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 PTR_ERR_OR_ZERO(dir); 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 if (val) 60 blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q); 61 else 62 blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q); 63 } 64 65 return count; 66 } 67 68 #endif /* CONFIG_FAIL_IO_TIMEOUT */ 69 70 /** 71 * blk_abort_request - Request recovery for the specified command 72 * @req: pointer to the request of interest 73 * 74 * This function requests that the block layer start recovery for the 75 * request by deleting the timer and calling the q's timeout function. 76 * LLDDs who implement their own error recovery MAY ignore the timeout 77 * event if they generated blk_abort_request. 78 */ 79 void blk_abort_request(struct request *req) 80 { 81 /* 82 * All we need to ensure is that timeout scan takes place 83 * immediately and that scan sees the new timeout value. 84 * No need for fancy synchronizations. 85 */ 86 WRITE_ONCE(req->deadline, jiffies); 87 kblockd_schedule_work(&req->q->timeout_work); 88 } 89 EXPORT_SYMBOL_GPL(blk_abort_request); 90 91 static unsigned long blk_timeout_mask __read_mostly; 92 93 static int __init blk_timeout_init(void) 94 { 95 blk_timeout_mask = roundup_pow_of_two(HZ) - 1; 96 return 0; 97 } 98 99 late_initcall(blk_timeout_init); 100 101 /* 102 * Just a rough estimate, we don't care about specific values for timeouts. 103 */ 104 static inline unsigned long blk_round_jiffies(unsigned long j) 105 { 106 return (j + blk_timeout_mask) + 1; 107 } 108 109 unsigned long blk_rq_timeout(unsigned long timeout) 110 { 111 unsigned long maxt; 112 113 maxt = blk_round_jiffies(jiffies + BLK_MAX_TIMEOUT); 114 if (time_after(timeout, maxt)) 115 timeout = maxt; 116 117 return timeout; 118 } 119 120 /** 121 * blk_add_timer - Start timeout timer for a single request 122 * @req: request that is about to start running. 123 * 124 * Notes: 125 * Each request has its own timer, and as it is added to the queue, we 126 * set up the timer. When the request completes, we cancel the timer. 127 */ 128 void blk_add_timer(struct request *req) 129 { 130 struct request_queue *q = req->q; 131 unsigned long expiry; 132 133 /* 134 * Some LLDs, like scsi, peek at the timeout to prevent a 135 * command from being retried forever. 136 */ 137 if (!req->timeout) 138 req->timeout = q->rq_timeout; 139 140 req->rq_flags &= ~RQF_TIMED_OUT; 141 142 expiry = jiffies + req->timeout; 143 WRITE_ONCE(req->deadline, expiry); 144 145 /* 146 * If the timer isn't already pending or this timeout is earlier 147 * than an existing one, modify the timer. Round up to next nearest 148 * second. 149 */ 150 expiry = blk_rq_timeout(blk_round_jiffies(expiry)); 151 152 if (!timer_pending(&q->timeout) || 153 time_before(expiry, q->timeout.expires)) { 154 unsigned long diff = q->timeout.expires - expiry; 155 156 /* 157 * Due to added timer slack to group timers, the timer 158 * will often be a little in front of what we asked for. 159 * So apply some tolerance here too, otherwise we keep 160 * modifying the timer because expires for value X 161 * will be X + something. 162 */ 163 if (!timer_pending(&q->timeout) || (diff >= HZ / 2)) 164 mod_timer(&q->timeout, expiry); 165 } 166 167 } 168