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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_delete_timer - Delete/cancel timer for a given function.
73 * @req: request that we are canceling timer for
74 *
75 */
76void blk_delete_timer(struct request *req)
77{
78 list_del_init(&req->timeout_list);
79}
80
81static void blk_rq_timed_out(struct request *req)
82{
83 struct request_queue *q = req->q;
84 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
85
86 if (q->rq_timed_out_fn)
87 ret = q->rq_timed_out_fn(req);
88 switch (ret) {
89 case BLK_EH_HANDLED:
90 __blk_complete_request(req);
91 break;
92 case BLK_EH_RESET_TIMER:
93 blk_add_timer(req);
94 blk_clear_rq_complete(req);
95 break;
96 case BLK_EH_NOT_HANDLED:
97 /*
98 * LLD handles this for now but in the future
99 * we can send a request msg to abort the command
100 * and we can move more of the generic scsi eh code to
101 * the blk layer.
102 */
103 break;
104 default:
105 printk(KERN_ERR "block: bad eh return: %d\n", ret);
106 break;
107 }
108}
109
110static void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout,
111 unsigned int *next_set)
112{
113 const unsigned long deadline = blk_rq_deadline(rq);
114
115 if (time_after_eq(jiffies, deadline)) {
116 list_del_init(&rq->timeout_list);
117
118 /*
119 * Check if we raced with end io completion
120 */
121 if (!blk_mark_rq_complete(rq))
122 blk_rq_timed_out(rq);
123 } else if (!*next_set || time_after(*next_timeout, deadline)) {
124 *next_timeout = deadline;
125 *next_set = 1;
126 }
127}
128
129void blk_timeout_work(struct work_struct *work)
130{
131 struct request_queue *q =
132 container_of(work, struct request_queue, timeout_work);
133 unsigned long flags, next = 0;
134 struct request *rq, *tmp;
135 int next_set = 0;
136
137 spin_lock_irqsave(q->queue_lock, flags);
138
139 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
140 blk_rq_check_expired(rq, &next, &next_set);
141
142 if (next_set)
143 mod_timer(&q->timeout, round_jiffies_up(next));
144
145 spin_unlock_irqrestore(q->queue_lock, flags);
146}
147
148/**
149 * blk_abort_request -- Request request recovery for the specified command
150 * @req: pointer to the request of interest
151 *
152 * This function requests that the block layer start recovery for the
153 * request by deleting the timer and calling the q's timeout function.
154 * LLDDs who implement their own error recovery MAY ignore the timeout
155 * event if they generated blk_abort_req. Must hold queue lock.
156 */
157void blk_abort_request(struct request *req)
158{
159 if (req->q->mq_ops) {
160 /*
161 * All we need to ensure is that timeout scan takes place
162 * immediately and that scan sees the new timeout value.
163 * No need for fancy synchronizations.
164 */
165 blk_rq_set_deadline(req, jiffies);
166 kblockd_schedule_work(&req->q->timeout_work);
167 } else {
168 if (blk_mark_rq_complete(req))
169 return;
170 blk_delete_timer(req);
171 blk_rq_timed_out(req);
172 }
173}
174EXPORT_SYMBOL_GPL(blk_abort_request);
175
176unsigned long blk_rq_timeout(unsigned long timeout)
177{
178 unsigned long maxt;
179
180 maxt = round_jiffies_up(jiffies + BLK_MAX_TIMEOUT);
181 if (time_after(timeout, maxt))
182 timeout = maxt;
183
184 return timeout;
185}
186
187/**
188 * blk_add_timer - Start timeout timer for a single request
189 * @req: request that is about to start running.
190 *
191 * Notes:
192 * Each request has its own timer, and as it is added to the queue, we
193 * set up the timer. When the request completes, we cancel the timer.
194 */
195void blk_add_timer(struct request *req)
196{
197 struct request_queue *q = req->q;
198 unsigned long expiry;
199
200 if (!q->mq_ops)
201 lockdep_assert_held(q->queue_lock);
202
203 /* blk-mq has its own handler, so we don't need ->rq_timed_out_fn */
204 if (!q->mq_ops && !q->rq_timed_out_fn)
205 return;
206
207 BUG_ON(!list_empty(&req->timeout_list));
208
209 /*
210 * Some LLDs, like scsi, peek at the timeout to prevent a
211 * command from being retried forever.
212 */
213 if (!req->timeout)
214 req->timeout = q->rq_timeout;
215
216 blk_rq_set_deadline(req, jiffies + req->timeout);
217 req->rq_flags &= ~RQF_MQ_TIMEOUT_EXPIRED;
218
219 /*
220 * Only the non-mq case needs to add the request to a protected list.
221 * For the mq case we simply scan the tag map.
222 */
223 if (!q->mq_ops)
224 list_add_tail(&req->timeout_list, &req->q->timeout_list);
225
226 /*
227 * If the timer isn't already pending or this timeout is earlier
228 * than an existing one, modify the timer. Round up to next nearest
229 * second.
230 */
231 expiry = blk_rq_timeout(round_jiffies_up(blk_rq_deadline(req)));
232
233 if (!timer_pending(&q->timeout) ||
234 time_before(expiry, q->timeout.expires)) {
235 unsigned long diff = q->timeout.expires - expiry;
236
237 /*
238 * Due to added timer slack to group timers, the timer
239 * will often be a little in front of what we asked for.
240 * So apply some tolerance here too, otherwise we keep
241 * modifying the timer because expires for value X
242 * will be X + something.
243 */
244 if (!timer_pending(&q->timeout) || (diff >= HZ / 2))
245 mod_timer(&q->timeout, expiry);
246 }
247
248}
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
15static DECLARE_FAULT_ATTR(fail_io_timeout);
16
17static 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
23bool __blk_should_fake_timeout(struct request_queue *q)
24{
25 return should_fail(&fail_io_timeout, 1);
26}
27EXPORT_SYMBOL_GPL(__blk_should_fake_timeout);
28
29static 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
37late_initcall(fail_io_timeout_debugfs);
38
39ssize_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
48ssize_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 */
79void 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}
89EXPORT_SYMBOL_GPL(blk_abort_request);
90
91static unsigned long blk_timeout_mask __read_mostly;
92
93static int __init blk_timeout_init(void)
94{
95 blk_timeout_mask = roundup_pow_of_two(HZ) - 1;
96 return 0;
97}
98
99late_initcall(blk_timeout_init);
100
101/*
102 * Just a rough estimate, we don't care about specific values for timeouts.
103 */
104static inline unsigned long blk_round_jiffies(unsigned long j)
105{
106 return (j + blk_timeout_mask) + 1;
107}
108
109unsigned 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 */
128void 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}