1 /* 2 * Infrastructure for statistic tracing (histogram output). 3 * 4 * Copyright (C) 2008-2009 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> 13 #include <linux/slab.h> 14 #include <linux/rbtree.h> 15 #include <linux/tracefs.h> 16 #include "trace_stat.h" 17 #include "trace.h" 18 19 20 /* 21 * List of stat red-black nodes from a tracer 22 * We use a such tree to sort quickly the stat 23 * entries from the tracer. 24 */ 25 struct stat_node { 26 struct rb_node node; 27 void *stat; 28 }; 29 30 /* A stat session is the stats output in one file */ 31 struct stat_session { 32 struct list_head session_list; 33 struct tracer_stat *ts; 34 struct rb_root stat_root; 35 struct mutex stat_mutex; 36 struct dentry *file; 37 }; 38 39 /* All of the sessions currently in use. Each stat file embed one session */ 40 static LIST_HEAD(all_stat_sessions); 41 static DEFINE_MUTEX(all_stat_sessions_mutex); 42 43 /* The root directory for all stat files */ 44 static struct dentry *stat_dir; 45 46 static void __reset_stat_session(struct stat_session *session) 47 { 48 struct stat_node *snode, *n; 49 50 rbtree_postorder_for_each_entry_safe(snode, n, &session->stat_root, node) { 51 if (session->ts->stat_release) 52 session->ts->stat_release(snode->stat); 53 kfree(snode); 54 } 55 56 session->stat_root = RB_ROOT; 57 } 58 59 static void reset_stat_session(struct stat_session *session) 60 { 61 mutex_lock(&session->stat_mutex); 62 __reset_stat_session(session); 63 mutex_unlock(&session->stat_mutex); 64 } 65 66 static void destroy_session(struct stat_session *session) 67 { 68 tracefs_remove(session->file); 69 __reset_stat_session(session); 70 mutex_destroy(&session->stat_mutex); 71 kfree(session); 72 } 73 74 typedef int (*cmp_stat_t)(void *, void *); 75 76 static int insert_stat(struct rb_root *root, void *stat, cmp_stat_t cmp) 77 { 78 struct rb_node **new = &(root->rb_node), *parent = NULL; 79 struct stat_node *data; 80 81 data = kzalloc(sizeof(*data), GFP_KERNEL); 82 if (!data) 83 return -ENOMEM; 84 data->stat = stat; 85 86 /* 87 * Figure out where to put new node 88 * This is a descendent sorting 89 */ 90 while (*new) { 91 struct stat_node *this; 92 int result; 93 94 this = container_of(*new, struct stat_node, node); 95 result = cmp(data->stat, this->stat); 96 97 parent = *new; 98 if (result >= 0) 99 new = &((*new)->rb_left); 100 else 101 new = &((*new)->rb_right); 102 } 103 104 rb_link_node(&data->node, parent, new); 105 rb_insert_color(&data->node, root); 106 return 0; 107 } 108 109 /* 110 * For tracers that don't provide a stat_cmp callback. 111 * This one will force an insertion as right-most node 112 * in the rbtree. 113 */ 114 static int dummy_cmp(void *p1, void *p2) 115 { 116 return -1; 117 } 118 119 /* 120 * Initialize the stat rbtree at each trace_stat file opening. 121 * All of these copies and sorting are required on all opening 122 * since the stats could have changed between two file sessions. 123 */ 124 static int stat_seq_init(struct stat_session *session) 125 { 126 struct tracer_stat *ts = session->ts; 127 struct rb_root *root = &session->stat_root; 128 void *stat; 129 int ret = 0; 130 int i; 131 132 mutex_lock(&session->stat_mutex); 133 __reset_stat_session(session); 134 135 if (!ts->stat_cmp) 136 ts->stat_cmp = dummy_cmp; 137 138 stat = ts->stat_start(ts); 139 if (!stat) 140 goto exit; 141 142 ret = insert_stat(root, stat, ts->stat_cmp); 143 if (ret) 144 goto exit; 145 146 /* 147 * Iterate over the tracer stat entries and store them in an rbtree. 148 */ 149 for (i = 1; ; i++) { 150 stat = ts->stat_next(stat, i); 151 152 /* End of insertion */ 153 if (!stat) 154 break; 155 156 ret = insert_stat(root, stat, ts->stat_cmp); 157 if (ret) 158 goto exit_free_rbtree; 159 } 160 161 exit: 162 mutex_unlock(&session->stat_mutex); 163 return ret; 164 165 exit_free_rbtree: 166 __reset_stat_session(session); 167 mutex_unlock(&session->stat_mutex); 168 return ret; 169 } 170 171 172 static void *stat_seq_start(struct seq_file *s, loff_t *pos) 173 { 174 struct stat_session *session = s->private; 175 struct rb_node *node; 176 int n = *pos; 177 int i; 178 179 /* Prevent from tracer switch or rbtree modification */ 180 mutex_lock(&session->stat_mutex); 181 182 /* If we are in the beginning of the file, print the headers */ 183 if (session->ts->stat_headers) { 184 if (n == 0) 185 return SEQ_START_TOKEN; 186 n--; 187 } 188 189 node = rb_first(&session->stat_root); 190 for (i = 0; node && i < n; i++) 191 node = rb_next(node); 192 193 return node; 194 } 195 196 static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos) 197 { 198 struct stat_session *session = s->private; 199 struct rb_node *node = p; 200 201 (*pos)++; 202 203 if (p == SEQ_START_TOKEN) 204 return rb_first(&session->stat_root); 205 206 return rb_next(node); 207 } 208 209 static void stat_seq_stop(struct seq_file *s, void *p) 210 { 211 struct stat_session *session = s->private; 212 mutex_unlock(&session->stat_mutex); 213 } 214 215 static int stat_seq_show(struct seq_file *s, void *v) 216 { 217 struct stat_session *session = s->private; 218 struct stat_node *l = container_of(v, struct stat_node, node); 219 220 if (v == SEQ_START_TOKEN) 221 return session->ts->stat_headers(s); 222 223 return session->ts->stat_show(s, l->stat); 224 } 225 226 static const struct seq_operations trace_stat_seq_ops = { 227 .start = stat_seq_start, 228 .next = stat_seq_next, 229 .stop = stat_seq_stop, 230 .show = stat_seq_show 231 }; 232 233 /* The session stat is refilled and resorted at each stat file opening */ 234 static int tracing_stat_open(struct inode *inode, struct file *file) 235 { 236 int ret; 237 struct seq_file *m; 238 struct stat_session *session = inode->i_private; 239 240 ret = stat_seq_init(session); 241 if (ret) 242 return ret; 243 244 ret = seq_open(file, &trace_stat_seq_ops); 245 if (ret) { 246 reset_stat_session(session); 247 return ret; 248 } 249 250 m = file->private_data; 251 m->private = session; 252 return ret; 253 } 254 255 /* 256 * Avoid consuming memory with our now useless rbtree. 257 */ 258 static int tracing_stat_release(struct inode *i, struct file *f) 259 { 260 struct stat_session *session = i->i_private; 261 262 reset_stat_session(session); 263 264 return seq_release(i, f); 265 } 266 267 static const struct file_operations tracing_stat_fops = { 268 .open = tracing_stat_open, 269 .read = seq_read, 270 .llseek = seq_lseek, 271 .release = tracing_stat_release 272 }; 273 274 static int tracing_stat_init(void) 275 { 276 struct dentry *d_tracing; 277 278 d_tracing = tracing_init_dentry(); 279 if (IS_ERR(d_tracing)) 280 return 0; 281 282 stat_dir = tracefs_create_dir("trace_stat", d_tracing); 283 if (!stat_dir) 284 pr_warn("Could not create tracefs 'trace_stat' entry\n"); 285 return 0; 286 } 287 288 static int init_stat_file(struct stat_session *session) 289 { 290 if (!stat_dir && tracing_stat_init()) 291 return -ENODEV; 292 293 session->file = tracefs_create_file(session->ts->name, 0644, 294 stat_dir, 295 session, &tracing_stat_fops); 296 if (!session->file) 297 return -ENOMEM; 298 return 0; 299 } 300 301 int register_stat_tracer(struct tracer_stat *trace) 302 { 303 struct stat_session *session, *node; 304 int ret; 305 306 if (!trace) 307 return -EINVAL; 308 309 if (!trace->stat_start || !trace->stat_next || !trace->stat_show) 310 return -EINVAL; 311 312 /* Already registered? */ 313 mutex_lock(&all_stat_sessions_mutex); 314 list_for_each_entry(node, &all_stat_sessions, session_list) { 315 if (node->ts == trace) { 316 mutex_unlock(&all_stat_sessions_mutex); 317 return -EINVAL; 318 } 319 } 320 mutex_unlock(&all_stat_sessions_mutex); 321 322 /* Init the session */ 323 session = kzalloc(sizeof(*session), GFP_KERNEL); 324 if (!session) 325 return -ENOMEM; 326 327 session->ts = trace; 328 INIT_LIST_HEAD(&session->session_list); 329 mutex_init(&session->stat_mutex); 330 331 ret = init_stat_file(session); 332 if (ret) { 333 destroy_session(session); 334 return ret; 335 } 336 337 /* Register */ 338 mutex_lock(&all_stat_sessions_mutex); 339 list_add_tail(&session->session_list, &all_stat_sessions); 340 mutex_unlock(&all_stat_sessions_mutex); 341 342 return 0; 343 } 344 345 void unregister_stat_tracer(struct tracer_stat *trace) 346 { 347 struct stat_session *node, *tmp; 348 349 mutex_lock(&all_stat_sessions_mutex); 350 list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) { 351 if (node->ts == trace) { 352 list_del(&node->session_list); 353 destroy_session(node); 354 break; 355 } 356 } 357 mutex_unlock(&all_stat_sessions_mutex); 358 } 359