| 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 | } |