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dbd0b4b3 FW |
1 | /* |
2 | * Infrastructure for statistic tracing (histogram output). | |
3 | * | |
4 | * Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com> | |
5 | * | |
6 | * Based on the code from trace_branch.c which is | |
7 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
8 | * | |
9 | */ | |
10 | ||
11 | ||
12 | #include <linux/list.h> | |
dbd0b4b3 | 13 | #include <linux/debugfs.h> |
002bb86d | 14 | #include "trace_stat.h" |
dbd0b4b3 FW |
15 | #include "trace.h" |
16 | ||
17 | ||
18 | /* List of stat entries from a tracer */ | |
19 | struct trace_stat_list { | |
55922173 IM |
20 | struct list_head list; |
21 | void *stat; | |
dbd0b4b3 FW |
22 | }; |
23 | ||
034939b6 FW |
24 | /* A stat session is the stats output in one file */ |
25 | struct tracer_stat_session { | |
002bb86d | 26 | struct list_head session_list; |
55922173 IM |
27 | struct tracer_stat *ts; |
28 | struct list_head stat_list; | |
29 | struct mutex stat_mutex; | |
002bb86d | 30 | struct dentry *file; |
034939b6 | 31 | }; |
dbd0b4b3 | 32 | |
73d8b8bc | 33 | /* All of the sessions currently in use. Each stat file embed one session */ |
002bb86d FW |
34 | static LIST_HEAD(all_stat_sessions); |
35 | static DEFINE_MUTEX(all_stat_sessions_mutex); | |
36 | ||
37 | /* The root directory for all stat files */ | |
55922173 | 38 | static struct dentry *stat_dir; |
dbd0b4b3 FW |
39 | |
40 | ||
034939b6 | 41 | static void reset_stat_session(struct tracer_stat_session *session) |
dbd0b4b3 | 42 | { |
ff288b27 | 43 | struct trace_stat_list *node, *next; |
dbd0b4b3 | 44 | |
034939b6 | 45 | list_for_each_entry_safe(node, next, &session->stat_list, list) |
dbd0b4b3 | 46 | kfree(node); |
dbd0b4b3 | 47 | |
034939b6 | 48 | INIT_LIST_HEAD(&session->stat_list); |
dbd0b4b3 FW |
49 | } |
50 | ||
002bb86d | 51 | static void destroy_session(struct tracer_stat_session *session) |
dbd0b4b3 | 52 | { |
002bb86d FW |
53 | debugfs_remove(session->file); |
54 | reset_stat_session(session); | |
55 | mutex_destroy(&session->stat_mutex); | |
56 | kfree(session); | |
57 | } | |
034939b6 | 58 | |
dbd0b4b3 FW |
59 | /* |
60 | * For tracers that don't provide a stat_cmp callback. | |
61 | * This one will force an immediate insertion on tail of | |
62 | * the list. | |
63 | */ | |
64 | static int dummy_cmp(void *p1, void *p2) | |
65 | { | |
66 | return 1; | |
67 | } | |
68 | ||
69 | /* | |
70 | * Initialize the stat list at each trace_stat file opening. | |
71 | * All of these copies and sorting are required on all opening | |
72 | * since the stats could have changed between two file sessions. | |
73 | */ | |
034939b6 | 74 | static int stat_seq_init(struct tracer_stat_session *session) |
dbd0b4b3 FW |
75 | { |
76 | struct trace_stat_list *iter_entry, *new_entry; | |
034939b6 | 77 | struct tracer_stat *ts = session->ts; |
dbd0b4b3 FW |
78 | void *prev_stat; |
79 | int ret = 0; | |
80 | int i; | |
81 | ||
034939b6 FW |
82 | mutex_lock(&session->stat_mutex); |
83 | reset_stat_session(session); | |
dbd0b4b3 | 84 | |
034939b6 FW |
85 | if (!ts->stat_cmp) |
86 | ts->stat_cmp = dummy_cmp; | |
dbd0b4b3 FW |
87 | |
88 | /* | |
89 | * The first entry. Actually this is the second, but the first | |
90 | * one (the stat_list head) is pointless. | |
91 | */ | |
92 | new_entry = kmalloc(sizeof(struct trace_stat_list), GFP_KERNEL); | |
93 | if (!new_entry) { | |
94 | ret = -ENOMEM; | |
95 | goto exit; | |
96 | } | |
97 | ||
98 | INIT_LIST_HEAD(&new_entry->list); | |
dbd0b4b3 | 99 | |
034939b6 FW |
100 | list_add(&new_entry->list, &session->stat_list); |
101 | ||
102 | new_entry->stat = ts->stat_start(); | |
dbd0b4b3 FW |
103 | prev_stat = new_entry->stat; |
104 | ||
105 | /* | |
106 | * Iterate over the tracer stat entries and store them in a sorted | |
107 | * list. | |
108 | */ | |
109 | for (i = 1; ; i++) { | |
110 | new_entry = kmalloc(sizeof(struct trace_stat_list), GFP_KERNEL); | |
111 | if (!new_entry) { | |
112 | ret = -ENOMEM; | |
113 | goto exit_free_list; | |
114 | } | |
115 | ||
116 | INIT_LIST_HEAD(&new_entry->list); | |
034939b6 | 117 | new_entry->stat = ts->stat_next(prev_stat, i); |
dbd0b4b3 FW |
118 | |
119 | /* End of insertion */ | |
120 | if (!new_entry->stat) | |
121 | break; | |
122 | ||
034939b6 FW |
123 | list_for_each_entry(iter_entry, &session->stat_list, list) { |
124 | ||
dbd0b4b3 | 125 | /* Insertion with a descendent sorting */ |
034939b6 | 126 | if (ts->stat_cmp(new_entry->stat, |
dbd0b4b3 FW |
127 | iter_entry->stat) > 0) { |
128 | ||
129 | list_add_tail(&new_entry->list, | |
130 | &iter_entry->list); | |
131 | break; | |
132 | ||
133 | /* The current smaller value */ | |
134 | } else if (list_is_last(&iter_entry->list, | |
034939b6 | 135 | &session->stat_list)) { |
dbd0b4b3 FW |
136 | list_add(&new_entry->list, &iter_entry->list); |
137 | break; | |
138 | } | |
139 | } | |
140 | ||
141 | prev_stat = new_entry->stat; | |
142 | } | |
143 | exit: | |
034939b6 | 144 | mutex_unlock(&session->stat_mutex); |
dbd0b4b3 FW |
145 | return ret; |
146 | ||
147 | exit_free_list: | |
034939b6 FW |
148 | reset_stat_session(session); |
149 | mutex_unlock(&session->stat_mutex); | |
dbd0b4b3 FW |
150 | return ret; |
151 | } | |
152 | ||
153 | ||
154 | static void *stat_seq_start(struct seq_file *s, loff_t *pos) | |
155 | { | |
034939b6 | 156 | struct tracer_stat_session *session = s->private; |
dbd0b4b3 FW |
157 | |
158 | /* Prevent from tracer switch or stat_list modification */ | |
034939b6 | 159 | mutex_lock(&session->stat_mutex); |
dbd0b4b3 FW |
160 | |
161 | /* If we are in the beginning of the file, print the headers */ | |
034939b6 FW |
162 | if (!*pos && session->ts->stat_headers) |
163 | session->ts->stat_headers(s); | |
dbd0b4b3 | 164 | |
034939b6 | 165 | return seq_list_start(&session->stat_list, *pos); |
dbd0b4b3 FW |
166 | } |
167 | ||
168 | static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos) | |
169 | { | |
034939b6 | 170 | struct tracer_stat_session *session = s->private; |
dbd0b4b3 | 171 | |
034939b6 | 172 | return seq_list_next(p, &session->stat_list, pos); |
dbd0b4b3 FW |
173 | } |
174 | ||
034939b6 | 175 | static void stat_seq_stop(struct seq_file *s, void *p) |
dbd0b4b3 | 176 | { |
034939b6 FW |
177 | struct tracer_stat_session *session = s->private; |
178 | mutex_unlock(&session->stat_mutex); | |
dbd0b4b3 FW |
179 | } |
180 | ||
181 | static int stat_seq_show(struct seq_file *s, void *v) | |
182 | { | |
034939b6 FW |
183 | struct tracer_stat_session *session = s->private; |
184 | struct trace_stat_list *l = list_entry(v, struct trace_stat_list, list); | |
ff288b27 | 185 | |
034939b6 | 186 | return session->ts->stat_show(s, l->stat); |
dbd0b4b3 FW |
187 | } |
188 | ||
189 | static const struct seq_operations trace_stat_seq_ops = { | |
55922173 IM |
190 | .start = stat_seq_start, |
191 | .next = stat_seq_next, | |
192 | .stop = stat_seq_stop, | |
193 | .show = stat_seq_show | |
dbd0b4b3 FW |
194 | }; |
195 | ||
034939b6 | 196 | /* The session stat is refilled and resorted at each stat file opening */ |
dbd0b4b3 FW |
197 | static int tracing_stat_open(struct inode *inode, struct file *file) |
198 | { | |
199 | int ret; | |
200 | ||
034939b6 FW |
201 | struct tracer_stat_session *session = inode->i_private; |
202 | ||
dbd0b4b3 FW |
203 | ret = seq_open(file, &trace_stat_seq_ops); |
204 | if (!ret) { | |
205 | struct seq_file *m = file->private_data; | |
034939b6 FW |
206 | m->private = session; |
207 | ret = stat_seq_init(session); | |
dbd0b4b3 FW |
208 | } |
209 | ||
210 | return ret; | |
211 | } | |
212 | ||
dbd0b4b3 FW |
213 | /* |
214 | * Avoid consuming memory with our now useless list. | |
215 | */ | |
216 | static int tracing_stat_release(struct inode *i, struct file *f) | |
217 | { | |
034939b6 FW |
218 | struct tracer_stat_session *session = i->i_private; |
219 | ||
220 | mutex_lock(&session->stat_mutex); | |
221 | reset_stat_session(session); | |
222 | mutex_unlock(&session->stat_mutex); | |
223 | ||
dbd0b4b3 FW |
224 | return 0; |
225 | } | |
226 | ||
227 | static const struct file_operations tracing_stat_fops = { | |
228 | .open = tracing_stat_open, | |
229 | .read = seq_read, | |
230 | .llseek = seq_lseek, | |
231 | .release = tracing_stat_release | |
232 | }; | |
233 | ||
002bb86d | 234 | static int tracing_stat_init(void) |
dbd0b4b3 FW |
235 | { |
236 | struct dentry *d_tracing; | |
dbd0b4b3 | 237 | |
dbd0b4b3 FW |
238 | d_tracing = tracing_init_dentry(); |
239 | ||
034939b6 FW |
240 | stat_dir = debugfs_create_dir("trace_stat", d_tracing); |
241 | if (!stat_dir) | |
dbd0b4b3 FW |
242 | pr_warning("Could not create debugfs " |
243 | "'trace_stat' entry\n"); | |
244 | return 0; | |
245 | } | |
002bb86d FW |
246 | |
247 | static int init_stat_file(struct tracer_stat_session *session) | |
248 | { | |
249 | if (!stat_dir && tracing_stat_init()) | |
250 | return -ENODEV; | |
251 | ||
252 | session->file = debugfs_create_file(session->ts->name, 0644, | |
253 | stat_dir, | |
254 | session, &tracing_stat_fops); | |
255 | if (!session->file) | |
256 | return -ENOMEM; | |
257 | return 0; | |
258 | } | |
55922173 IM |
259 | |
260 | int register_stat_tracer(struct tracer_stat *trace) | |
261 | { | |
262 | struct tracer_stat_session *session, *node, *tmp; | |
263 | int ret; | |
264 | ||
265 | if (!trace) | |
266 | return -EINVAL; | |
267 | ||
268 | if (!trace->stat_start || !trace->stat_next || !trace->stat_show) | |
269 | return -EINVAL; | |
270 | ||
271 | /* Already registered? */ | |
272 | mutex_lock(&all_stat_sessions_mutex); | |
273 | list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) { | |
274 | if (node->ts == trace) { | |
275 | mutex_unlock(&all_stat_sessions_mutex); | |
276 | return -EINVAL; | |
277 | } | |
278 | } | |
279 | mutex_unlock(&all_stat_sessions_mutex); | |
280 | ||
281 | /* Init the session */ | |
282 | session = kmalloc(sizeof(struct tracer_stat_session), GFP_KERNEL); | |
283 | if (!session) | |
284 | return -ENOMEM; | |
285 | ||
286 | session->ts = trace; | |
287 | INIT_LIST_HEAD(&session->session_list); | |
288 | INIT_LIST_HEAD(&session->stat_list); | |
289 | mutex_init(&session->stat_mutex); | |
290 | session->file = NULL; | |
291 | ||
292 | ret = init_stat_file(session); | |
293 | if (ret) { | |
294 | destroy_session(session); | |
295 | return ret; | |
296 | } | |
297 | ||
298 | /* Register */ | |
299 | mutex_lock(&all_stat_sessions_mutex); | |
300 | list_add_tail(&session->session_list, &all_stat_sessions); | |
301 | mutex_unlock(&all_stat_sessions_mutex); | |
302 | ||
303 | return 0; | |
304 | } | |
305 | ||
306 | void unregister_stat_tracer(struct tracer_stat *trace) | |
307 | { | |
308 | struct tracer_stat_session *node, *tmp; | |
309 | ||
310 | mutex_lock(&all_stat_sessions_mutex); | |
311 | list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) { | |
312 | if (node->ts == trace) { | |
313 | list_del(&node->session_list); | |
314 | destroy_session(node); | |
315 | break; | |
316 | } | |
317 | } | |
318 | mutex_unlock(&all_stat_sessions_mutex); | |
319 | } |