tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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
11#ifdef CONFIG_FAIL_IO_TIMEOUT
12
13static DECLARE_FAULT_ATTR(fail_io_timeout);
14
15static int __init setup_fail_io_timeout(char *str)
16{
17 return setup_fault_attr(&fail_io_timeout, str);
18}
19__setup("fail_io_timeout=", setup_fail_io_timeout);
20
21int blk_should_fake_timeout(struct request_queue *q)
22{
23 if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
24 return 0;
25
26 return should_fail(&fail_io_timeout, 1);
27}
28
29static int __init fail_io_timeout_debugfs(void)
30{
31 return init_fault_attr_dentries(&fail_io_timeout, "fail_io_timeout");
32}
33
34late_initcall(fail_io_timeout_debugfs);
35
36ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
37 char *buf)
38{
39 struct gendisk *disk = dev_to_disk(dev);
40 int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
41
42 return sprintf(buf, "%d\n", set != 0);
43}
44
45ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
46 const char *buf, size_t count)
47{
48 struct gendisk *disk = dev_to_disk(dev);
49 int val;
50
51 if (count) {
52 struct request_queue *q = disk->queue;
53 char *p = (char *) buf;
54
55 val = simple_strtoul(p, &p, 10);
56 spin_lock_irq(q->queue_lock);
57 if (val)
58 queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
59 else
60 queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
61 spin_unlock_irq(q->queue_lock);
62 }
63
64 return count;
65}
66
67#endif /* CONFIG_FAIL_IO_TIMEOUT */
68
69/*
70 * blk_delete_timer - Delete/cancel timer for a given function.
71 * @req: request that we are canceling timer for
72 *
73 */
74void blk_delete_timer(struct request *req)
75{
76 struct request_queue *q = req->q;
77
78 list_del_init(&req->timeout_list);
79 if (list_empty(&q->timeout_list))
80 del_timer(&q->timeout);
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;
87
88 ret = q->rq_timed_out_fn(req);
89 switch (ret) {
90 case BLK_EH_HANDLED:
91 __blk_complete_request(req);
92 break;
93 case BLK_EH_RESET_TIMER:
94 blk_clear_rq_complete(req);
95 blk_add_timer(req);
96 break;
97 case BLK_EH_NOT_HANDLED:
98 /*
99 * LLD handles this for now but in the future
100 * we can send a request msg to abort the command
101 * and we can move more of the generic scsi eh code to
102 * the blk layer.
103 */
104 break;
105 default:
106 printk(KERN_ERR "block: bad eh return: %d\n", ret);
107 break;
108 }
109}
110
111void blk_rq_timed_out_timer(unsigned long data)
112{
113 struct request_queue *q = (struct request_queue *) data;
114 unsigned long flags, uninitialized_var(next), next_set = 0;
115 struct request *rq, *tmp;
116
117 spin_lock_irqsave(q->queue_lock, flags);
118
119 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) {
120 if (time_after_eq(jiffies, rq->deadline)) {
121 list_del_init(&rq->timeout_list);
122
123 /*
124 * Check if we raced with end io completion
125 */
126 if (blk_mark_rq_complete(rq))
127 continue;
128 blk_rq_timed_out(rq);
129 }
130 if (!next_set) {
131 next = rq->deadline;
132 next_set = 1;
133 } else if (time_after(next, rq->deadline))
134 next = rq->deadline;
135 }
136
137 if (next_set && !list_empty(&q->timeout_list))
138 mod_timer(&q->timeout, round_jiffies_up(next));
139
140 spin_unlock_irqrestore(q->queue_lock, flags);
141}
142
143/**
144 * blk_abort_request -- Request request recovery for the specified command
145 * @req: pointer to the request of interest
146 *
147 * This function requests that the block layer start recovery for the
148 * request by deleting the timer and calling the q's timeout function.
149 * LLDDs who implement their own error recovery MAY ignore the timeout
150 * event if they generated blk_abort_req. Must hold queue lock.
151 */
152void blk_abort_request(struct request *req)
153{
154 if (blk_mark_rq_complete(req))
155 return;
156 blk_delete_timer(req);
157 blk_rq_timed_out(req);
158}
159EXPORT_SYMBOL_GPL(blk_abort_request);
160
161/**
162 * blk_add_timer - Start timeout timer for a single request
163 * @req: request that is about to start running.
164 *
165 * Notes:
166 * Each request has its own timer, and as it is added to the queue, we
167 * set up the timer. When the request completes, we cancel the timer.
168 */
169void blk_add_timer(struct request *req)
170{
171 struct request_queue *q = req->q;
172 unsigned long expiry;
173
174 if (!q->rq_timed_out_fn)
175 return;
176
177 BUG_ON(!list_empty(&req->timeout_list));
178 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
179
180 if (req->timeout)
181 req->deadline = jiffies + req->timeout;
182 else {
183 req->deadline = jiffies + q->rq_timeout;
184 /*
185 * Some LLDs, like scsi, peek at the timeout to prevent
186 * a command from being retried forever.
187 */
188 req->timeout = q->rq_timeout;
189 }
190 list_add_tail(&req->timeout_list, &q->timeout_list);
191
192 /*
193 * If the timer isn't already pending or this timeout is earlier
194 * than an existing one, modify the timer. Round up to next nearest
195 * second.
196 */
197 expiry = round_jiffies_up(req->deadline);
198
199 if (!timer_pending(&q->timeout) ||
200 time_before(expiry, q->timeout.expires))
201 mod_timer(&q->timeout, expiry);
202}
203
204/**
205 * blk_abort_queue -- Abort all request on given queue
206 * @queue: pointer to queue
207 *
208 */
209void blk_abort_queue(struct request_queue *q)
210{
211 unsigned long flags;
212 struct request *rq, *tmp;
213
214 spin_lock_irqsave(q->queue_lock, flags);
215
216 elv_abort_queue(q);
217
218 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
219 blk_abort_request(rq);
220
221 spin_unlock_irqrestore(q->queue_lock, flags);
222
223}
224EXPORT_SYMBOL_GPL(blk_abort_queue);