kernel/trace/trace

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This source file includes following definitions.
__reset_stat_session
reset_stat_session
destroy_session
insert_stat
dummy_cmp
stat_seq_init
stat_seq_start
stat_seq_next
stat_seq_stop
stat_seq_show
tracing_stat_open
tracing_stat_release
tracing_stat_init
init_stat_file
register_stat_tracer
unregister_stat_tracer
   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Infrastructure for statistic tracing (histogram output).
   4  *
   5  * Copyright (C) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
   6  *
   7  * Based on the code from trace_branch.c which is
   8  * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
   9  *
  10  */
  11 
  12 #include <linux/security.h>
  13 #include <linux/list.h>
  14 #include <linux/slab.h>
  15 #include <linux/rbtree.h>
  16 #include <linux/tracefs.h>
  17 #include "trace_stat.h"
  18 #include "trace.h"
  19 
  20 
  21 /*
  22  * List of stat red-black nodes from a tracer
  23  * We use a such tree to sort quickly the stat
  24  * entries from the tracer.
  25  */
  26 struct stat_node {
  27         struct rb_node          node;
  28         void                    *stat;
  29 };
  30 
  31 /* A stat session is the stats output in one file */
  32 struct stat_session {
  33         struct list_head        session_list;
  34         struct tracer_stat      *ts;
  35         struct rb_root          stat_root;
  36         struct mutex            stat_mutex;
  37         struct dentry           *file;
  38 };
  39 
  40 /* All of the sessions currently in use. Each stat file embed one session */
  41 static LIST_HEAD(all_stat_sessions);
  42 static DEFINE_MUTEX(all_stat_sessions_mutex);
  43 
  44 /* The root directory for all stat files */
  45 static struct dentry            *stat_dir;
  46 
  47 static void __reset_stat_session(struct stat_session *session)
  48 {
  49         struct stat_node *snode, *n;
  50 
  51         rbtree_postorder_for_each_entry_safe(snode, n, &session->stat_root, node) {
  52                 if (session->ts->stat_release)
  53                         session->ts->stat_release(snode->stat);
  54                 kfree(snode);
  55         }
  56 
  57         session->stat_root = RB_ROOT;
  58 }
  59 
  60 static void reset_stat_session(struct stat_session *session)
  61 {
  62         mutex_lock(&session->stat_mutex);
  63         __reset_stat_session(session);
  64         mutex_unlock(&session->stat_mutex);
  65 }
  66 
  67 static void destroy_session(struct stat_session *session)
  68 {
  69         tracefs_remove(session->file);
  70         __reset_stat_session(session);
  71         mutex_destroy(&session->stat_mutex);
  72         kfree(session);
  73 }
  74 
  75 typedef int (*cmp_stat_t)(void *, void *);
  76 
  77 static int insert_stat(struct rb_root *root, void *stat, cmp_stat_t cmp)
  78 {
  79         struct rb_node **new = &(root->rb_node), *parent = NULL;
  80         struct stat_node *data;
  81 
  82         data = kzalloc(sizeof(*data), GFP_KERNEL);
  83         if (!data)
  84                 return -ENOMEM;
  85         data->stat = stat;
  86 
  87         /*
  88          * Figure out where to put new node
  89          * This is a descendent sorting
  90          */
  91         while (*new) {
  92                 struct stat_node *this;
  93                 int result;
  94 
  95                 this = container_of(*new, struct stat_node, node);
  96                 result = cmp(data->stat, this->stat);
  97 
  98                 parent = *new;
  99                 if (result >= 0)
 100                         new = &((*new)->rb_left);
 101                 else
 102                         new = &((*new)->rb_right);
 103         }
 104 
 105         rb_link_node(&data->node, parent, new);
 106         rb_insert_color(&data->node, root);
 107         return 0;
 108 }
 109 
 110 /*
 111  * For tracers that don't provide a stat_cmp callback.
 112  * This one will force an insertion as right-most node
 113  * in the rbtree.
 114  */
 115 static int dummy_cmp(void *p1, void *p2)
 116 {
 117         return -1;
 118 }
 119 
 120 /*
 121  * Initialize the stat rbtree at each trace_stat file opening.
 122  * All of these copies and sorting are required on all opening
 123  * since the stats could have changed between two file sessions.
 124  */
 125 static int stat_seq_init(struct stat_session *session)
 126 {
 127         struct tracer_stat *ts = session->ts;
 128         struct rb_root *root = &session->stat_root;
 129         void *stat;
 130         int ret = 0;
 131         int i;
 132 
 133         mutex_lock(&session->stat_mutex);
 134         __reset_stat_session(session);
 135 
 136         if (!ts->stat_cmp)
 137                 ts->stat_cmp = dummy_cmp;
 138 
 139         stat = ts->stat_start(ts);
 140         if (!stat)
 141                 goto exit;
 142 
 143         ret = insert_stat(root, stat, ts->stat_cmp);
 144         if (ret)
 145                 goto exit;
 146 
 147         /*
 148          * Iterate over the tracer stat entries and store them in an rbtree.
 149          */
 150         for (i = 1; ; i++) {
 151                 stat = ts->stat_next(stat, i);
 152 
 153                 /* End of insertion */
 154                 if (!stat)
 155                         break;
 156 
 157                 ret = insert_stat(root, stat, ts->stat_cmp);
 158                 if (ret)
 159                         goto exit_free_rbtree;
 160         }
 161 
 162 exit:
 163         mutex_unlock(&session->stat_mutex);
 164         return ret;
 165 
 166 exit_free_rbtree:
 167         __reset_stat_session(session);
 168         mutex_unlock(&session->stat_mutex);
 169         return ret;
 170 }
 171 
 172 
 173 static void *stat_seq_start(struct seq_file *s, loff_t *pos)
 174 {
 175         struct stat_session *session = s->private;
 176         struct rb_node *node;
 177         int n = *pos;
 178         int i;
 179 
 180         /* Prevent from tracer switch or rbtree modification */
 181         mutex_lock(&session->stat_mutex);
 182 
 183         /* If we are in the beginning of the file, print the headers */
 184         if (session->ts->stat_headers) {
 185                 if (n == 0)
 186                         return SEQ_START_TOKEN;
 187                 n--;
 188         }
 189 
 190         node = rb_first(&session->stat_root);
 191         for (i = 0; node && i < n; i++)
 192                 node = rb_next(node);
 193 
 194         return node;
 195 }
 196 
 197 static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
 198 {
 199         struct stat_session *session = s->private;
 200         struct rb_node *node = p;
 201 
 202         (*pos)++;
 203 
 204         if (p == SEQ_START_TOKEN)
 205                 return rb_first(&session->stat_root);
 206 
 207         return rb_next(node);
 208 }
 209 
 210 static void stat_seq_stop(struct seq_file *s, void *p)
 211 {
 212         struct stat_session *session = s->private;
 213         mutex_unlock(&session->stat_mutex);
 214 }
 215 
 216 static int stat_seq_show(struct seq_file *s, void *v)
 217 {
 218         struct stat_session *session = s->private;
 219         struct stat_node *l = container_of(v, struct stat_node, node);
 220 
 221         if (v == SEQ_START_TOKEN)
 222                 return session->ts->stat_headers(s);
 223 
 224         return session->ts->stat_show(s, l->stat);
 225 }
 226 
 227 static const struct seq_operations trace_stat_seq_ops = {
 228         .start          = stat_seq_start,
 229         .next           = stat_seq_next,
 230         .stop           = stat_seq_stop,
 231         .show           = stat_seq_show
 232 };
 233 
 234 /* The session stat is refilled and resorted at each stat file opening */
 235 static int tracing_stat_open(struct inode *inode, struct file *file)
 236 {
 237         int ret;
 238         struct seq_file *m;
 239         struct stat_session *session = inode->i_private;
 240 
 241         ret = security_locked_down(LOCKDOWN_TRACEFS);
 242         if (ret)
 243                 return ret;
 244 
 245         ret = stat_seq_init(session);
 246         if (ret)
 247                 return ret;
 248 
 249         ret = seq_open(file, &trace_stat_seq_ops);
 250         if (ret) {
 251                 reset_stat_session(session);
 252                 return ret;
 253         }
 254 
 255         m = file->private_data;
 256         m->private = session;
 257         return ret;
 258 }
 259 
 260 /*
 261  * Avoid consuming memory with our now useless rbtree.
 262  */
 263 static int tracing_stat_release(struct inode *i, struct file *f)
 264 {
 265         struct stat_session *session = i->i_private;
 266 
 267         reset_stat_session(session);
 268 
 269         return seq_release(i, f);
 270 }
 271 
 272 static const struct file_operations tracing_stat_fops = {
 273         .open           = tracing_stat_open,
 274         .read           = seq_read,
 275         .llseek         = seq_lseek,
 276         .release        = tracing_stat_release
 277 };
 278 
 279 static int tracing_stat_init(void)
 280 {
 281         struct dentry *d_tracing;
 282 
 283         d_tracing = tracing_init_dentry();
 284         if (IS_ERR(d_tracing))
 285                 return -ENODEV;
 286 
 287         stat_dir = tracefs_create_dir("trace_stat", d_tracing);
 288         if (!stat_dir) {
 289                 pr_warn("Could not create tracefs 'trace_stat' entry\n");
 290                 return -ENOMEM;
 291         }
 292         return 0;
 293 }
 294 
 295 static int init_stat_file(struct stat_session *session)
 296 {
 297         int ret;
 298 
 299         if (!stat_dir && (ret = tracing_stat_init()))
 300                 return ret;
 301 
 302         session->file = tracefs_create_file(session->ts->name, 0644,
 303                                             stat_dir,
 304                                             session, &tracing_stat_fops);
 305         if (!session->file)
 306                 return -ENOMEM;
 307         return 0;
 308 }
 309 
 310 int register_stat_tracer(struct tracer_stat *trace)
 311 {
 312         struct stat_session *session, *node;
 313         int ret = -EINVAL;
 314 
 315         if (!trace)
 316                 return -EINVAL;
 317 
 318         if (!trace->stat_start || !trace->stat_next || !trace->stat_show)
 319                 return -EINVAL;
 320 
 321         /* Already registered? */
 322         mutex_lock(&all_stat_sessions_mutex);
 323         list_for_each_entry(node, &all_stat_sessions, session_list) {
 324                 if (node->ts == trace)
 325                         goto out;
 326         }
 327 
 328         ret = -ENOMEM;
 329         /* Init the session */
 330         session = kzalloc(sizeof(*session), GFP_KERNEL);
 331         if (!session)
 332                 goto out;
 333 
 334         session->ts = trace;
 335         INIT_LIST_HEAD(&session->session_list);
 336         mutex_init(&session->stat_mutex);
 337 
 338         ret = init_stat_file(session);
 339         if (ret) {
 340                 destroy_session(session);
 341                 goto out;
 342         }
 343 
 344         ret = 0;
 345         /* Register */
 346         list_add_tail(&session->session_list, &all_stat_sessions);
 347  out:
 348         mutex_unlock(&all_stat_sessions_mutex);
 349 
 350         return ret;
 351 }
 352 
 353 void unregister_stat_tracer(struct tracer_stat *trace)
 354 {
 355         struct stat_session *node, *tmp;
 356 
 357         mutex_lock(&all_stat_sessions_mutex);
 358         list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
 359                 if (node->ts == trace) {
 360                         list_del(&node->session_list);
 361                         destroy_session(node);
 362                         break;
 363                 }
 364         }
 365         mutex_unlock(&all_stat_sessions_mutex);
 366 }
/* [<][>][^][v][top][bottom][index][help] */
root/kernel/trace/trace_stat.c

DEFINITIONS
