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
14static DECLARE_FAULT_ATTR(fail_io_timeout);
15
16static 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
22int 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
30static 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
38late_initcall(fail_io_timeout_debugfs);
39
40ssize_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
49ssize_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 */
80void 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}
90EXPORT_SYMBOL_GPL(blk_abort_request);
91
92unsigned 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 */
111void 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