Commit | Line | Data |
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242f9dcb JA |
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 | ||
8 | #include "blk.h" | |
9 | ||
10 | /* | |
11 | * blk_delete_timer - Delete/cancel timer for a given function. | |
12 | * @req: request that we are canceling timer for | |
13 | * | |
14 | */ | |
15 | void blk_delete_timer(struct request *req) | |
16 | { | |
17 | struct request_queue *q = req->q; | |
18 | ||
19 | /* | |
20 | * Nothing to detach | |
21 | */ | |
22 | if (!q->rq_timed_out_fn || !req->deadline) | |
23 | return; | |
24 | ||
25 | list_del_init(&req->timeout_list); | |
26 | ||
27 | if (list_empty(&q->timeout_list)) | |
28 | del_timer(&q->timeout); | |
29 | } | |
30 | ||
31 | static void blk_rq_timed_out(struct request *req) | |
32 | { | |
33 | struct request_queue *q = req->q; | |
34 | enum blk_eh_timer_return ret; | |
35 | ||
36 | ret = q->rq_timed_out_fn(req); | |
37 | switch (ret) { | |
38 | case BLK_EH_HANDLED: | |
39 | __blk_complete_request(req); | |
40 | break; | |
41 | case BLK_EH_RESET_TIMER: | |
42 | blk_clear_rq_complete(req); | |
43 | blk_add_timer(req); | |
44 | break; | |
45 | case BLK_EH_NOT_HANDLED: | |
46 | /* | |
47 | * LLD handles this for now but in the future | |
48 | * we can send a request msg to abort the command | |
49 | * and we can move more of the generic scsi eh code to | |
50 | * the blk layer. | |
51 | */ | |
52 | break; | |
53 | default: | |
54 | printk(KERN_ERR "block: bad eh return: %d\n", ret); | |
55 | break; | |
56 | } | |
57 | } | |
58 | ||
59 | void blk_rq_timed_out_timer(unsigned long data) | |
60 | { | |
61 | struct request_queue *q = (struct request_queue *) data; | |
62 | unsigned long flags, uninitialized_var(next), next_set = 0; | |
63 | struct request *rq, *tmp; | |
64 | ||
65 | spin_lock_irqsave(q->queue_lock, flags); | |
66 | ||
67 | list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) { | |
68 | if (time_after_eq(jiffies, rq->deadline)) { | |
69 | list_del_init(&rq->timeout_list); | |
70 | ||
71 | /* | |
72 | * Check if we raced with end io completion | |
73 | */ | |
74 | if (blk_mark_rq_complete(rq)) | |
75 | continue; | |
76 | blk_rq_timed_out(rq); | |
77 | } | |
78 | if (!next_set) { | |
79 | next = rq->deadline; | |
80 | next_set = 1; | |
81 | } else if (time_after(next, rq->deadline)) | |
82 | next = rq->deadline; | |
83 | } | |
84 | ||
85 | if (next_set && !list_empty(&q->timeout_list)) | |
86 | mod_timer(&q->timeout, round_jiffies(next)); | |
87 | ||
88 | spin_unlock_irqrestore(q->queue_lock, flags); | |
89 | } | |
90 | ||
91 | /** | |
92 | * blk_abort_request -- Request request recovery for the specified command | |
93 | * @req: pointer to the request of interest | |
94 | * | |
95 | * This function requests that the block layer start recovery for the | |
96 | * request by deleting the timer and calling the q's timeout function. | |
97 | * LLDDs who implement their own error recovery MAY ignore the timeout | |
98 | * event if they generated blk_abort_req. Must hold queue lock. | |
99 | */ | |
100 | void blk_abort_request(struct request *req) | |
101 | { | |
102 | blk_delete_timer(req); | |
103 | blk_rq_timed_out(req); | |
104 | } | |
105 | EXPORT_SYMBOL_GPL(blk_abort_request); | |
106 | ||
107 | /** | |
108 | * blk_add_timer - Start timeout timer for a single request | |
109 | * @req: request that is about to start running. | |
110 | * | |
111 | * Notes: | |
112 | * Each request has its own timer, and as it is added to the queue, we | |
113 | * set up the timer. When the request completes, we cancel the timer. | |
114 | */ | |
115 | void blk_add_timer(struct request *req) | |
116 | { | |
117 | struct request_queue *q = req->q; | |
118 | unsigned long expiry; | |
119 | ||
120 | if (!q->rq_timed_out_fn) | |
121 | return; | |
122 | ||
123 | BUG_ON(!list_empty(&req->timeout_list)); | |
124 | BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags)); | |
125 | ||
126 | if (req->timeout) | |
127 | req->deadline = jiffies + req->timeout; | |
128 | else { | |
129 | req->deadline = jiffies + q->rq_timeout; | |
130 | /* | |
131 | * Some LLDs, like scsi, peek at the timeout to prevent | |
132 | * a command from being retried forever. | |
133 | */ | |
134 | req->timeout = q->rq_timeout; | |
135 | } | |
136 | list_add_tail(&req->timeout_list, &q->timeout_list); | |
137 | ||
138 | /* | |
139 | * If the timer isn't already pending or this timeout is earlier | |
140 | * than an existing one, modify the timer. Round to next nearest | |
141 | * second. | |
142 | */ | |
143 | expiry = round_jiffies(req->deadline); | |
144 | ||
145 | /* | |
146 | * We use ->deadline == 0 to detect whether a timer was added or | |
147 | * not, so just increase to next jiffy for that specific case | |
148 | */ | |
149 | if (unlikely(!req->deadline)) | |
150 | req->deadline = 1; | |
151 | ||
152 | if (!timer_pending(&q->timeout) || | |
153 | time_before(expiry, q->timeout.expires)) | |
154 | mod_timer(&q->timeout, expiry); | |
155 | } |