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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 | struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout", |
32 | NULL, &fail_io_timeout); |
33 | |
34 | return IS_ERR(dir) ? PTR_ERR(dir) : 0; |
35 | } |
36 | |
37 | late_initcall(fail_io_timeout_debugfs); |
38 | |
39 | ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr, |
40 | char *buf) |
41 | { |
42 | struct gendisk *disk = dev_to_disk(dev); |
43 | int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags); |
44 | |
45 | return sprintf(buf, "%d\n", set != 0); |
46 | } |
47 | |
48 | ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr, |
49 | const char *buf, size_t count) |
50 | { |
51 | struct gendisk *disk = dev_to_disk(dev); |
52 | int val; |
53 | |
54 | if (count) { |
55 | struct request_queue *q = disk->queue; |
56 | char *p = (char *) buf; |
57 | |
58 | val = simple_strtoul(p, &p, 10); |
59 | spin_lock_irq(q->queue_lock); |
60 | if (val) |
61 | queue_flag_set(QUEUE_FLAG_FAIL_IO, q); |
62 | else |
63 | queue_flag_clear(QUEUE_FLAG_FAIL_IO, q); |
64 | spin_unlock_irq(q->queue_lock); |
65 | } |
66 | |
67 | return count; |
68 | } |
69 | |
70 | #endif /* CONFIG_FAIL_IO_TIMEOUT */ |
71 | |
72 | /* |
73 | * blk_delete_timer - Delete/cancel timer for a given function. |
74 | * @req: request that we are canceling timer for |
75 | * |
76 | */ |
77 | void blk_delete_timer(struct request *req) |
78 | { |
79 | list_del_init(&req->timeout_list); |
80 | } |
81 | |
82 | static void blk_rq_timed_out(struct request *req) |
83 | { |
84 | struct request_queue *q = req->q; |
85 | enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER; |
86 | |
87 | if (q->rq_timed_out_fn) |
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 | |
111 | void blk_rq_timed_out_timer(unsigned long data) |
112 | { |
113 | struct request_queue *q = (struct request_queue *) data; |
114 | unsigned long flags, next = 0; |
115 | struct request *rq, *tmp; |
116 | int next_set = 0; |
117 | |
118 | spin_lock_irqsave(q->queue_lock, flags); |
119 | |
120 | list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) { |
121 | if (time_after_eq(jiffies, rq->deadline)) { |
122 | list_del_init(&rq->timeout_list); |
123 | |
124 | /* |
125 | * Check if we raced with end io completion |
126 | */ |
127 | if (blk_mark_rq_complete(rq)) |
128 | continue; |
129 | blk_rq_timed_out(rq); |
130 | } else if (!next_set || time_after(next, rq->deadline)) { |
131 | next = rq->deadline; |
132 | next_set = 1; |
133 | } |
134 | } |
135 | |
136 | if (next_set) |
137 | mod_timer(&q->timeout, round_jiffies_up(next)); |
138 | |
139 | spin_unlock_irqrestore(q->queue_lock, flags); |
140 | } |
141 | |
142 | /** |
143 | * blk_abort_request -- Request request recovery for the specified command |
144 | * @req: pointer to the request of interest |
145 | * |
146 | * This function requests that the block layer start recovery for the |
147 | * request by deleting the timer and calling the q's timeout function. |
148 | * LLDDs who implement their own error recovery MAY ignore the timeout |
149 | * event if they generated blk_abort_req. Must hold queue lock. |
150 | */ |
151 | void blk_abort_request(struct request *req) |
152 | { |
153 | if (blk_mark_rq_complete(req)) |
154 | return; |
155 | blk_delete_timer(req); |
156 | blk_rq_timed_out(req); |
157 | } |
158 | EXPORT_SYMBOL_GPL(blk_abort_request); |
159 | |
160 | /** |
161 | * blk_add_timer - Start timeout timer for a single request |
162 | * @req: request that is about to start running. |
163 | * |
164 | * Notes: |
165 | * Each request has its own timer, and as it is added to the queue, we |
166 | * set up the timer. When the request completes, we cancel the timer. |
167 | */ |
168 | void blk_add_timer(struct request *req) |
169 | { |
170 | struct request_queue *q = req->q; |
171 | unsigned long expiry; |
172 | |
173 | if (!q->rq_timed_out_fn) |
174 | return; |
175 | |
176 | BUG_ON(!list_empty(&req->timeout_list)); |
177 | BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags)); |
178 | |
179 | /* |
180 | * Some LLDs, like scsi, peek at the timeout to prevent a |
181 | * command from being retried forever. |
182 | */ |
183 | if (!req->timeout) |
184 | req->timeout = q->rq_timeout; |
185 | |
186 | req->deadline = jiffies + req->timeout; |
187 | list_add_tail(&req->timeout_list, &q->timeout_list); |
188 | |
189 | /* |
190 | * If the timer isn't already pending or this timeout is earlier |
191 | * than an existing one, modify the timer. Round up to next nearest |
192 | * second. |
193 | */ |
194 | expiry = round_jiffies_up(req->deadline); |
195 | |
196 | if (!timer_pending(&q->timeout) || |
197 | time_before(expiry, q->timeout.expires)) |
198 | mod_timer(&q->timeout, expiry); |
199 | } |
200 | |
201 |
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