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	list_del_init(&req->timeout_list);
77}
78
79static 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
107void 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	int next_set = 0;
113
114	spin_lock_irqsave(q->queue_lock, flags);
115
116	list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) {
117		if (time_after_eq(jiffies, rq->deadline)) {
118			list_del_init(&rq->timeout_list);
119
120			/*
121			 * Check if we raced with end io completion
122			 */
123			if (blk_mark_rq_complete(rq))
124				continue;
125			blk_rq_timed_out(rq);
126		} else if (!next_set || time_after(next, rq->deadline)) {
127			next = rq->deadline;
128			next_set = 1;
129		}
130	}
131
132	if (next_set)
133		mod_timer(&q->timeout, round_jiffies_up(next));
134
135	spin_unlock_irqrestore(q->queue_lock, flags);
136}
137
138/**
139 * blk_abort_request -- Request request recovery for the specified command
140 * @req:	pointer to the request of interest
141 *
142 * This function requests that the block layer start recovery for the
143 * request by deleting the timer and calling the q's timeout function.
144 * LLDDs who implement their own error recovery MAY ignore the timeout
145 * event if they generated blk_abort_req. Must hold queue lock.
146 */
147void blk_abort_request(struct request *req)
148{
149	if (blk_mark_rq_complete(req))
150		return;
151	blk_delete_timer(req);
152	blk_rq_timed_out(req);
153}
154EXPORT_SYMBOL_GPL(blk_abort_request);
155
156/**
157 * blk_add_timer - Start timeout timer for a single request
158 * @req:	request that is about to start running.
159 *
160 * Notes:
161 *    Each request has its own timer, and as it is added to the queue, we
162 *    set up the timer. When the request completes, we cancel the timer.
163 */
164void blk_add_timer(struct request *req)
165{
166	struct request_queue *q = req->q;
167	unsigned long expiry;
168
169	if (!q->rq_timed_out_fn)
170		return;
171
172	BUG_ON(!list_empty(&req->timeout_list));
173	BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
174
175	/*
176	 * Some LLDs, like scsi, peek at the timeout to prevent a
177	 * command from being retried forever.
178	 */
179	if (!req->timeout)
180		req->timeout = q->rq_timeout;
181
182	req->deadline = jiffies + req->timeout;
183	list_add_tail(&req->timeout_list, &q->timeout_list);
184
185	/*
186	 * If the timer isn't already pending or this timeout is earlier
187	 * than an existing one, modify the timer. Round up to next nearest
188	 * second.
189	 */
190	expiry = round_jiffies_up(req->deadline);
191
192	if (!timer_pending(&q->timeout) ||
193	    time_before(expiry, q->timeout.expires))
194		mod_timer(&q->timeout, expiry);
195}
196
197/**
198 * blk_abort_queue -- Abort all request on given queue
199 * @queue:	pointer to queue
200 *
201 */
202void blk_abort_queue(struct request_queue *q)
203{
204	unsigned long flags;
205	struct request *rq, *tmp;
206	LIST_HEAD(list);
207
208	/*
209	 * Not a request based block device, nothing to abort
210	 */
211	if (!q->request_fn)
212		return;
213
214	spin_lock_irqsave(q->queue_lock, flags);
215
216	elv_abort_queue(q);
217
218	/*
219	 * Splice entries to local list, to avoid deadlocking if entries
220	 * get readded to the timeout list by error handling
221	 */
222	list_splice_init(&q->timeout_list, &list);
223
224	list_for_each_entry_safe(rq, tmp, &list, timeout_list)
225		blk_abort_request(rq);
226
227	/*
228	 * Occasionally, blk_abort_request() will return without
229	 * deleting the element from the list. Make sure we add those back
230	 * instead of leaving them on the local stack list.
231	 */
232	list_splice(&list, &q->timeout_list);
233
234	spin_unlock_irqrestore(q->queue_lock, flags);
235
236}
237EXPORT_SYMBOL_GPL(blk_abort_queue);
238