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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 | /* |
60 | * Describe a slow work item for debugfs |
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 | /* |
214 | * open "/sys/kernel/debug/slow_work/runqueue" to list queue contents |
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 | }; |
228 |
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