1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Functions related to generic timeout handling of requests. |
4 | */ |
5 | #include <linux/kernel.h> |
6 | #include <linux/module.h> |
7 | #include <linux/blkdev.h> |
8 | #include <linux/fault-inject.h> |
9 | |
10 | #include "blk.h" |
11 | #include "blk-mq.h" |
12 | |
13 | #ifdef CONFIG_FAIL_IO_TIMEOUT |
14 | |
15 | static DECLARE_FAULT_ATTR(fail_io_timeout); |
16 | |
17 | static int __init setup_fail_io_timeout(char *str) |
18 | { |
19 | return setup_fault_attr(attr: &fail_io_timeout, str); |
20 | } |
21 | __setup("fail_io_timeout=" , setup_fail_io_timeout); |
22 | |
23 | bool __blk_should_fake_timeout(struct request_queue *q) |
24 | { |
25 | return should_fail(attr: &fail_io_timeout, size: 1); |
26 | } |
27 | EXPORT_SYMBOL_GPL(__blk_should_fake_timeout); |
28 | |
29 | static int __init fail_io_timeout_debugfs(void) |
30 | { |
31 | struct dentry *dir = fault_create_debugfs_attr(name: "fail_io_timeout" , |
32 | NULL, attr: &fail_io_timeout); |
33 | |
34 | return PTR_ERR_OR_ZERO(ptr: dir); |
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, fmt: "%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 | if (val) |
60 | blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q); |
61 | else |
62 | blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q); |
63 | } |
64 | |
65 | return count; |
66 | } |
67 | |
68 | #endif /* CONFIG_FAIL_IO_TIMEOUT */ |
69 | |
70 | /** |
71 | * blk_abort_request - Request recovery for the specified command |
72 | * @req: pointer to the request of interest |
73 | * |
74 | * This function requests that the block layer start recovery for the |
75 | * request by deleting the timer and calling the q's timeout function. |
76 | * LLDDs who implement their own error recovery MAY ignore the timeout |
77 | * event if they generated blk_abort_request. |
78 | */ |
79 | void blk_abort_request(struct request *req) |
80 | { |
81 | /* |
82 | * All we need to ensure is that timeout scan takes place |
83 | * immediately and that scan sees the new timeout value. |
84 | * No need for fancy synchronizations. |
85 | */ |
86 | WRITE_ONCE(req->deadline, jiffies); |
87 | kblockd_schedule_work(work: &req->q->timeout_work); |
88 | } |
89 | EXPORT_SYMBOL_GPL(blk_abort_request); |
90 | |
91 | static unsigned long blk_timeout_mask __read_mostly; |
92 | |
93 | static int __init blk_timeout_init(void) |
94 | { |
95 | blk_timeout_mask = roundup_pow_of_two(HZ) - 1; |
96 | return 0; |
97 | } |
98 | |
99 | late_initcall(blk_timeout_init); |
100 | |
101 | /* |
102 | * Just a rough estimate, we don't care about specific values for timeouts. |
103 | */ |
104 | static inline unsigned long blk_round_jiffies(unsigned long j) |
105 | { |
106 | return (j + blk_timeout_mask) + 1; |
107 | } |
108 | |
109 | unsigned long blk_rq_timeout(unsigned long timeout) |
110 | { |
111 | unsigned long maxt; |
112 | |
113 | maxt = blk_round_jiffies(j: jiffies + BLK_MAX_TIMEOUT); |
114 | if (time_after(timeout, maxt)) |
115 | timeout = maxt; |
116 | |
117 | return timeout; |
118 | } |
119 | |
120 | /** |
121 | * blk_add_timer - Start timeout timer for a single request |
122 | * @req: request that is about to start running. |
123 | * |
124 | * Notes: |
125 | * Each request has its own timer, and as it is added to the queue, we |
126 | * set up the timer. When the request completes, we cancel the timer. |
127 | */ |
128 | void blk_add_timer(struct request *req) |
129 | { |
130 | struct request_queue *q = req->q; |
131 | unsigned long expiry; |
132 | |
133 | /* |
134 | * Some LLDs, like scsi, peek at the timeout to prevent a |
135 | * command from being retried forever. |
136 | */ |
137 | if (!req->timeout) |
138 | req->timeout = q->rq_timeout; |
139 | |
140 | req->rq_flags &= ~RQF_TIMED_OUT; |
141 | |
142 | expiry = jiffies + req->timeout; |
143 | WRITE_ONCE(req->deadline, expiry); |
144 | |
145 | /* |
146 | * If the timer isn't already pending or this timeout is earlier |
147 | * than an existing one, modify the timer. Round up to next nearest |
148 | * second. |
149 | */ |
150 | expiry = blk_rq_timeout(timeout: blk_round_jiffies(j: expiry)); |
151 | |
152 | if (!timer_pending(timer: &q->timeout) || |
153 | time_before(expiry, q->timeout.expires)) { |
154 | unsigned long diff = q->timeout.expires - expiry; |
155 | |
156 | /* |
157 | * Due to added timer slack to group timers, the timer |
158 | * will often be a little in front of what we asked for. |
159 | * So apply some tolerance here too, otherwise we keep |
160 | * modifying the timer because expires for value X |
161 | * will be X + something. |
162 | */ |
163 | if (!timer_pending(timer: &q->timeout) || (diff >= HZ / 2)) |
164 | mod_timer(timer: &q->timeout, expires: expiry); |
165 | } |
166 | |
167 | } |
168 | |