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
13 static DECLARE_FAULT_ATTR(fail_io_timeout);
14
15 static 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
21 int 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
29 static int __init fail_io_timeout_debugfs(void)
30 {
31 return init_fault_attr_dentries(&fail_io_timeout, "fail_io_timeout");
32 }
33
34 late_initcall(fail_io_timeout_debugfs);
35
36 ssize_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
45 ssize_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 */
74 void blk_delete_timer(struct request *req)
75 {
76 list_del_init(&req->timeout_list);
77 }
78
79 static void blk_rq_timed_out(struct request *req)
80 {
81 struct request_queue *q = req->q;
82 enum blk_eh_timer_return ret;
83
84 ret = q->rq_timed_out_fn(req);
85 switch (ret) {
86 case BLK_EH_HANDLED:
87 __blk_complete_request(req);
88 break;
89 case BLK_EH_RESET_TIMER:
90 blk_clear_rq_complete(req);
91 blk_add_timer(req);
92 break;
93 case BLK_EH_NOT_HANDLED:
94 /*
95 * LLD handles this for now but in the future
96 * we can send a request msg to abort the command
97 * and we can move more of the generic scsi eh code to
98 * the blk layer.
99 */
100 break;
101 default:
102 printk(KERN_ERR "block: bad eh return: %d\n", ret);
103 break;
104 }
105 }
106
107 void blk_rq_timed_out_timer(unsigned long data)
108 {
109 struct request_queue *q = (struct request_queue *) data;
110 unsigned long flags, next = 0;
111 struct request *rq, *tmp;
112
113 spin_lock_irqsave(q->queue_lock, flags);
114
115 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) {
116 if (time_after_eq(jiffies, rq->deadline)) {
117 list_del_init(&rq->timeout_list);
118
119 /*
120 * Check if we raced with end io completion
121 */
122 if (blk_mark_rq_complete(rq))
123 continue;
124 blk_rq_timed_out(rq);
125 } else if (!next || time_after(next, rq->deadline))
126 next = rq->deadline;
127 }
128
129 /*
130 * next can never be 0 here with the list non-empty, since we always
131 * bump ->deadline to 1 so we can detect if the timer was ever added
132 * or not. See comment in blk_add_timer()
133 */
134 if (next)
135 mod_timer(&q->timeout, round_jiffies_up(next));
136
137 spin_unlock_irqrestore(q->queue_lock, flags);
138 }
139
140 /**
141 * blk_abort_request -- Request request recovery for the specified command
142 * @req: pointer to the request of interest
143 *
144 * This function requests that the block layer start recovery for the
145 * request by deleting the timer and calling the q's timeout function.
146 * LLDDs who implement their own error recovery MAY ignore the timeout
147 * event if they generated blk_abort_req. Must hold queue lock.
148 */
149 void blk_abort_request(struct request *req)
150 {
151 if (blk_mark_rq_complete(req))
152 return;
153 blk_delete_timer(req);
154 blk_rq_timed_out(req);
155 }
156 EXPORT_SYMBOL_GPL(blk_abort_request);
157
158 /**
159 * blk_add_timer - Start timeout timer for a single request
160 * @req: request that is about to start running.
161 *
162 * Notes:
163 * Each request has its own timer, and as it is added to the queue, we
164 * set up the timer. When the request completes, we cancel the timer.
165 */
166 void blk_add_timer(struct request *req)
167 {
168 struct request_queue *q = req->q;
169 unsigned long expiry;
170
171 if (!q->rq_timed_out_fn)
172 return;
173
174 BUG_ON(!list_empty(&req->timeout_list));
175 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
176
177 /*
178 * Some LLDs, like scsi, peek at the timeout to prevent a
179 * command from being retried forever.
180 */
181 if (!req->timeout)
182 req->timeout = q->rq_timeout;
183
184 req->deadline = jiffies + req->timeout;
185 list_add_tail(&req->timeout_list, &q->timeout_list);
186
187 /*
188 * If the timer isn't already pending or this timeout is earlier
189 * than an existing one, modify the timer. Round up to next nearest
190 * second.
191 */
192 expiry = round_jiffies_up(req->deadline);
193
194 if (!timer_pending(&q->timeout) ||
195 time_before(expiry, q->timeout.expires))
196 mod_timer(&q->timeout, expiry);
197 }
198
199 /**
200 * blk_abort_queue -- Abort all request on given queue
201 * @queue: pointer to queue
202 *
203 */
204 void blk_abort_queue(struct request_queue *q)
205 {
206 unsigned long flags;
207 struct request *rq, *tmp;
208 LIST_HEAD(list);
209
210 /*
211 * Not a request based block device, nothing to abort
212 */
213 if (!q->request_fn)
214 return;
215
216 spin_lock_irqsave(q->queue_lock, flags);
217
218 elv_abort_queue(q);
219
220 /*
221 * Splice entries to local list, to avoid deadlocking if entries
222 * get readded to the timeout list by error handling
223 */
224 list_splice_init(&q->timeout_list, &list);
225
226 list_for_each_entry_safe(rq, tmp, &list, timeout_list)
227 blk_abort_request(rq);
228
229 /*
230 * Occasionally, blk_abort_request() will return without
231 * deleting the element from the list. Make sure we add those back
232 * instead of leaving them on the local stack list.
233 */
234 list_splice(&list, &q->timeout_list);
235
236 spin_unlock_irqrestore(q->queue_lock, flags);
237
238 }
239 EXPORT_SYMBOL_GPL(blk_abort_queue);
240
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