Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 spin_lock_irq(q->queue_lock);
61 if (val)
62 queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
63 else
64 queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
65 spin_unlock_irq(q->queue_lock);
66 }
67
68 return count;
69}
70
71#endif /* CONFIG_FAIL_IO_TIMEOUT */
72
73/*
74 * blk_delete_timer - Delete/cancel timer for a given function.
75 * @req: request that we are canceling timer for
76 *
77 */
78void blk_delete_timer(struct request *req)
79{
80 list_del_init(&req->timeout_list);
81}
82
83static void blk_rq_timed_out(struct request *req)
84{
85 struct request_queue *q = req->q;
86 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
87
88 if (q->rq_timed_out_fn)
89 ret = q->rq_timed_out_fn(req);
90 switch (ret) {
91 case BLK_EH_HANDLED:
92 /* Can we use req->errors here? */
93 if (q->mq_ops)
94 blk_mq_complete_request(req, req->errors);
95 else
96 __blk_complete_request(req);
97 break;
98 case BLK_EH_RESET_TIMER:
99 if (q->mq_ops)
100 blk_mq_add_timer(req);
101 else
102 blk_add_timer(req);
103
104 blk_clear_rq_complete(req);
105 break;
106 case BLK_EH_NOT_HANDLED:
107 /*
108 * LLD handles this for now but in the future
109 * we can send a request msg to abort the command
110 * and we can move more of the generic scsi eh code to
111 * the blk layer.
112 */
113 break;
114 default:
115 printk(KERN_ERR "block: bad eh return: %d\n", ret);
116 break;
117 }
118}
119
120void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout,
121 unsigned int *next_set)
122{
123 if (time_after_eq(jiffies, rq->deadline)) {
124 list_del_init(&rq->timeout_list);
125
126 /*
127 * Check if we raced with end io completion
128 */
129 if (!blk_mark_rq_complete(rq))
130 blk_rq_timed_out(rq);
131 } else if (!*next_set || time_after(*next_timeout, rq->deadline)) {
132 *next_timeout = rq->deadline;
133 *next_set = 1;
134 }
135}
136
137void blk_rq_timed_out_timer(unsigned long data)
138{
139 struct request_queue *q = (struct request_queue *) data;
140 unsigned long flags, next = 0;
141 struct request *rq, *tmp;
142 int next_set = 0;
143
144 spin_lock_irqsave(q->queue_lock, flags);
145
146 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
147 blk_rq_check_expired(rq, &next, &next_set);
148
149 if (next_set)
150 mod_timer(&q->timeout, round_jiffies_up(next));
151
152 spin_unlock_irqrestore(q->queue_lock, flags);
153}
154
155/**
156 * blk_abort_request -- Request request recovery for the specified command
157 * @req: pointer to the request of interest
158 *
159 * This function requests that the block layer start recovery for the
160 * request by deleting the timer and calling the q's timeout function.
161 * LLDDs who implement their own error recovery MAY ignore the timeout
162 * event if they generated blk_abort_req. Must hold queue lock.
163 */
164void blk_abort_request(struct request *req)
165{
166 if (blk_mark_rq_complete(req))
167 return;
168 blk_delete_timer(req);
169 blk_rq_timed_out(req);
170}
171EXPORT_SYMBOL_GPL(blk_abort_request);
172
173void __blk_add_timer(struct request *req, struct list_head *timeout_list)
174{
175 struct request_queue *q = req->q;
176 unsigned long expiry;
177
178 if (!q->rq_timed_out_fn)
179 return;
180
181 BUG_ON(!list_empty(&req->timeout_list));
182
183 /*
184 * Some LLDs, like scsi, peek at the timeout to prevent a
185 * command from being retried forever.
186 */
187 if (!req->timeout)
188 req->timeout = q->rq_timeout;
189
190 req->deadline = jiffies + req->timeout;
191 if (timeout_list)
192 list_add_tail(&req->timeout_list, timeout_list);
193
194 /*
195 * If the timer isn't already pending or this timeout is earlier
196 * than an existing one, modify the timer. Round up to next nearest
197 * second.
198 */
199 expiry = round_jiffies_up(req->deadline);
200
201 if (!timer_pending(&q->timeout) ||
202 time_before(expiry, q->timeout.expires))
203 mod_timer(&q->timeout, expiry);
204
205}
206
207/**
208 * blk_add_timer - Start timeout timer for a single request
209 * @req: request that is about to start running.
210 *
211 * Notes:
212 * Each request has its own timer, and as it is added to the queue, we
213 * set up the timer. When the request completes, we cancel the timer.
214 */
215void blk_add_timer(struct request *req)
216{
217 __blk_add_timer(req, &req->q->timeout_list);
218}
219