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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 | } |