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8fba10a4 DH |
1 | /* Slow work debugging |
2 | * | |
3 | * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public Licence | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the Licence, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/slow-work.h> | |
14 | #include <linux/fs.h> | |
15 | #include <linux/time.h> | |
16 | #include <linux/seq_file.h> | |
17 | #include "slow-work.h" | |
18 | ||
19 | #define ITERATOR_SHIFT (BITS_PER_LONG - 4) | |
20 | #define ITERATOR_SELECTOR (0xfUL << ITERATOR_SHIFT) | |
21 | #define ITERATOR_COUNTER (~ITERATOR_SELECTOR) | |
22 | ||
23 | void slow_work_new_thread_desc(struct slow_work *work, struct seq_file *m) | |
24 | { | |
25 | seq_puts(m, "Slow-work: New thread"); | |
26 | } | |
27 | ||
28 | /* | |
29 | * Render the time mark field on a work item into a 5-char time with units plus | |
30 | * a space | |
31 | */ | |
32 | static void slow_work_print_mark(struct seq_file *m, struct slow_work *work) | |
33 | { | |
34 | struct timespec now, diff; | |
35 | ||
36 | now = CURRENT_TIME; | |
37 | diff = timespec_sub(now, work->mark); | |
38 | ||
39 | if (diff.tv_sec < 0) | |
40 | seq_puts(m, " -ve "); | |
41 | else if (diff.tv_sec == 0 && diff.tv_nsec < 1000) | |
42 | seq_printf(m, "%3luns ", diff.tv_nsec); | |
43 | else if (diff.tv_sec == 0 && diff.tv_nsec < 1000000) | |
44 | seq_printf(m, "%3luus ", diff.tv_nsec / 1000); | |
45 | else if (diff.tv_sec == 0 && diff.tv_nsec < 1000000000) | |
46 | seq_printf(m, "%3lums ", diff.tv_nsec / 1000000); | |
47 | else if (diff.tv_sec <= 1) | |
48 | seq_puts(m, " 1s "); | |
49 | else if (diff.tv_sec < 60) | |
50 | seq_printf(m, "%4lus ", diff.tv_sec); | |
51 | else if (diff.tv_sec < 60 * 60) | |
52 | seq_printf(m, "%4lum ", diff.tv_sec / 60); | |
53 | else if (diff.tv_sec < 60 * 60 * 24) | |
54 | seq_printf(m, "%4luh ", diff.tv_sec / 3600); | |
55 | else | |
56 | seq_puts(m, "exces "); | |
57 | } | |
58 | ||
59 | /* | |
f13a48bd | 60 | * Describe a slow work item for debugfs |
8fba10a4 DH |
61 | */ |
62 | static int slow_work_runqueue_show(struct seq_file *m, void *v) | |
63 | { | |
64 | struct slow_work *work; | |
65 | struct list_head *p = v; | |
66 | unsigned long id; | |
67 | ||
68 | switch ((unsigned long) v) { | |
69 | case 1: | |
70 | seq_puts(m, "THR PID ITEM ADDR FL MARK DESC\n"); | |
71 | return 0; | |
72 | case 2: | |
73 | seq_puts(m, "=== ===== ================ == ===== ==========\n"); | |
74 | return 0; | |
75 | ||
76 | case 3 ... 3 + SLOW_WORK_THREAD_LIMIT - 1: | |
77 | id = (unsigned long) v - 3; | |
78 | ||
79 | read_lock(&slow_work_execs_lock); | |
80 | work = slow_work_execs[id]; | |
81 | if (work) { | |
82 | smp_read_barrier_depends(); | |
83 | ||
84 | seq_printf(m, "%3lu %5d %16p %2lx ", | |
85 | id, slow_work_pids[id], work, work->flags); | |
86 | slow_work_print_mark(m, work); | |
87 | ||
88 | if (work->ops->desc) | |
89 | work->ops->desc(work, m); | |
90 | seq_putc(m, '\n'); | |
91 | } | |
92 | read_unlock(&slow_work_execs_lock); | |
93 | return 0; | |
94 | ||
95 | default: | |
96 | work = list_entry(p, struct slow_work, link); | |
97 | seq_printf(m, "%3s - %16p %2lx ", | |
98 | work->flags & SLOW_WORK_VERY_SLOW ? "vsq" : "sq", | |
99 | work, work->flags); | |
100 | slow_work_print_mark(m, work); | |
101 | ||
102 | if (work->ops->desc) | |
103 | work->ops->desc(work, m); | |
104 | seq_putc(m, '\n'); | |
105 | return 0; | |
106 | } | |
107 | } | |
108 | ||
109 | /* | |
110 | * map the iterator to a work item | |
111 | */ | |
112 | static void *slow_work_runqueue_index(struct seq_file *m, loff_t *_pos) | |
113 | { | |
114 | struct list_head *p; | |
115 | unsigned long count, id; | |
116 | ||
117 | switch (*_pos >> ITERATOR_SHIFT) { | |
118 | case 0x0: | |
119 | if (*_pos == 0) | |
120 | *_pos = 1; | |
121 | if (*_pos < 3) | |
122 | return (void *)(unsigned long) *_pos; | |
123 | if (*_pos < 3 + SLOW_WORK_THREAD_LIMIT) | |
124 | for (id = *_pos - 3; | |
125 | id < SLOW_WORK_THREAD_LIMIT; | |
126 | id++, (*_pos)++) | |
127 | if (slow_work_execs[id]) | |
128 | return (void *)(unsigned long) *_pos; | |
129 | *_pos = 0x1UL << ITERATOR_SHIFT; | |
130 | ||
131 | case 0x1: | |
132 | count = *_pos & ITERATOR_COUNTER; | |
133 | list_for_each(p, &slow_work_queue) { | |
134 | if (count == 0) | |
135 | return p; | |
136 | count--; | |
137 | } | |
138 | *_pos = 0x2UL << ITERATOR_SHIFT; | |
139 | ||
140 | case 0x2: | |
141 | count = *_pos & ITERATOR_COUNTER; | |
142 | list_for_each(p, &vslow_work_queue) { | |
143 | if (count == 0) | |
144 | return p; | |
145 | count--; | |
146 | } | |
147 | *_pos = 0x3UL << ITERATOR_SHIFT; | |
148 | ||
149 | default: | |
150 | return NULL; | |
151 | } | |
152 | } | |
153 | ||
154 | /* | |
155 | * set up the iterator to start reading from the first line | |
156 | */ | |
157 | static void *slow_work_runqueue_start(struct seq_file *m, loff_t *_pos) | |
158 | { | |
159 | spin_lock_irq(&slow_work_queue_lock); | |
160 | return slow_work_runqueue_index(m, _pos); | |
161 | } | |
162 | ||
163 | /* | |
164 | * move to the next line | |
165 | */ | |
166 | static void *slow_work_runqueue_next(struct seq_file *m, void *v, loff_t *_pos) | |
167 | { | |
168 | struct list_head *p = v; | |
169 | unsigned long selector = *_pos >> ITERATOR_SHIFT; | |
170 | ||
171 | (*_pos)++; | |
172 | switch (selector) { | |
173 | case 0x0: | |
174 | return slow_work_runqueue_index(m, _pos); | |
175 | ||
176 | case 0x1: | |
177 | if (*_pos >> ITERATOR_SHIFT == 0x1) { | |
178 | p = p->next; | |
179 | if (p != &slow_work_queue) | |
180 | return p; | |
181 | } | |
182 | *_pos = 0x2UL << ITERATOR_SHIFT; | |
183 | p = &vslow_work_queue; | |
184 | ||
185 | case 0x2: | |
186 | if (*_pos >> ITERATOR_SHIFT == 0x2) { | |
187 | p = p->next; | |
188 | if (p != &vslow_work_queue) | |
189 | return p; | |
190 | } | |
191 | *_pos = 0x3UL << ITERATOR_SHIFT; | |
192 | ||
193 | default: | |
194 | return NULL; | |
195 | } | |
196 | } | |
197 | ||
198 | /* | |
199 | * clean up after reading | |
200 | */ | |
201 | static void slow_work_runqueue_stop(struct seq_file *m, void *v) | |
202 | { | |
203 | spin_unlock_irq(&slow_work_queue_lock); | |
204 | } | |
205 | ||
206 | static const struct seq_operations slow_work_runqueue_ops = { | |
207 | .start = slow_work_runqueue_start, | |
208 | .stop = slow_work_runqueue_stop, | |
209 | .next = slow_work_runqueue_next, | |
210 | .show = slow_work_runqueue_show, | |
211 | }; | |
212 | ||
213 | /* | |
f13a48bd | 214 | * open "/sys/kernel/debug/slow_work/runqueue" to list queue contents |
8fba10a4 DH |
215 | */ |
216 | static int slow_work_runqueue_open(struct inode *inode, struct file *file) | |
217 | { | |
218 | return seq_open(file, &slow_work_runqueue_ops); | |
219 | } | |
220 | ||
221 | const struct file_operations slow_work_runqueue_fops = { | |
222 | .owner = THIS_MODULE, | |
223 | .open = slow_work_runqueue_open, | |
224 | .read = seq_read, | |
225 | .llseek = seq_lseek, | |
226 | .release = seq_release, | |
227 | }; |