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
setup_fail_io_timeout(char * str)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
blk_should_fake_timeout(struct request_queue * q)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
fail_io_timeout_debugfs(void)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
part_timeout_show(struct device * dev,struct device_attribute * attr,char * buf)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
part_timeout_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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 */
blk_abort_request(struct request * req)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
blk_rq_timeout(unsigned long timeout)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 */
blk_add_timer(struct request * req)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
