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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 | |
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 | 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 | */ |
147 | void 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 | } |
154 | EXPORT_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 | */ |
164 | void 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 | */ |
202 | void 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 | } |
237 | EXPORT_SYMBOL_GPL(blk_abort_queue); |
238 |
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