Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2008 Mathieu Desnoyers |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | */ |
| 18 | #include <linux/module.h> |
| 19 | #include <linux/mutex.h> |
| 20 | #include <linux/types.h> |
| 21 | #include <linux/jhash.h> |
| 22 | #include <linux/list.h> |
| 23 | #include <linux/rcupdate.h> |
| 24 | #include <linux/tracepoint.h> |
| 25 | #include <linux/err.h> |
| 26 | #include <linux/slab.h> |
| 27 | |
| 28 | extern struct tracepoint __start___tracepoints[]; |
| 29 | extern struct tracepoint __stop___tracepoints[]; |
| 30 | |
| 31 | /* Set to 1 to enable tracepoint debug output */ |
| 32 | static const int tracepoint_debug; |
| 33 | |
| 34 | /* |
| 35 | * tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the |
| 36 | * builtin and module tracepoints and the hash table. |
| 37 | */ |
| 38 | static DEFINE_MUTEX(tracepoints_mutex); |
| 39 | |
| 40 | /* |
| 41 | * Tracepoint hash table, containing the active tracepoints. |
| 42 | * Protected by tracepoints_mutex. |
| 43 | */ |
| 44 | #define TRACEPOINT_HASH_BITS 6 |
| 45 | #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS) |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 46 | static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE]; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 47 | |
| 48 | /* |
| 49 | * Note about RCU : |
| 50 | * It is used to to delay the free of multiple probes array until a quiescent |
| 51 | * state is reached. |
| 52 | * Tracepoint entries modifications are protected by the tracepoints_mutex. |
| 53 | */ |
| 54 | struct tracepoint_entry { |
| 55 | struct hlist_node hlist; |
| 56 | void **funcs; |
| 57 | int refcount; /* Number of times armed. 0 if disarmed. */ |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 58 | char name[0]; |
| 59 | }; |
| 60 | |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 61 | struct tp_probes { |
Lai Jiangshan | 127cafb | 2008-10-28 10:51:53 +0800 | [diff] [blame] | 62 | union { |
| 63 | struct rcu_head rcu; |
| 64 | struct list_head list; |
| 65 | } u; |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 66 | void *probes[0]; |
| 67 | }; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 68 | |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 69 | static inline void *allocate_probes(int count) |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 70 | { |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 71 | struct tp_probes *p = kmalloc(count * sizeof(void *) |
| 72 | + sizeof(struct tp_probes), GFP_KERNEL); |
| 73 | return p == NULL ? NULL : p->probes; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 74 | } |
| 75 | |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 76 | static void rcu_free_old_probes(struct rcu_head *head) |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 77 | { |
Lai Jiangshan | 127cafb | 2008-10-28 10:51:53 +0800 | [diff] [blame] | 78 | kfree(container_of(head, struct tp_probes, u.rcu)); |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 79 | } |
| 80 | |
| 81 | static inline void release_probes(void *old) |
| 82 | { |
| 83 | if (old) { |
| 84 | struct tp_probes *tp_probes = container_of(old, |
| 85 | struct tp_probes, probes[0]); |
Lai Jiangshan | 127cafb | 2008-10-28 10:51:53 +0800 | [diff] [blame] | 86 | call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes); |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 87 | } |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 88 | } |
| 89 | |
| 90 | static void debug_print_probes(struct tracepoint_entry *entry) |
| 91 | { |
| 92 | int i; |
| 93 | |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 94 | if (!tracepoint_debug || !entry->funcs) |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 95 | return; |
| 96 | |
| 97 | for (i = 0; entry->funcs[i]; i++) |
| 98 | printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i]); |
| 99 | } |
| 100 | |
| 101 | static void * |
| 102 | tracepoint_entry_add_probe(struct tracepoint_entry *entry, void *probe) |
| 103 | { |
| 104 | int nr_probes = 0; |
| 105 | void **old, **new; |
| 106 | |
| 107 | WARN_ON(!probe); |
| 108 | |
| 109 | debug_print_probes(entry); |
| 110 | old = entry->funcs; |
| 111 | if (old) { |
| 112 | /* (N -> N+1), (N != 0, 1) probes */ |
| 113 | for (nr_probes = 0; old[nr_probes]; nr_probes++) |
| 114 | if (old[nr_probes] == probe) |
| 115 | return ERR_PTR(-EEXIST); |
| 116 | } |
| 117 | /* + 2 : one for new probe, one for NULL func */ |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 118 | new = allocate_probes(nr_probes + 2); |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 119 | if (new == NULL) |
| 120 | return ERR_PTR(-ENOMEM); |
| 121 | if (old) |
| 122 | memcpy(new, old, nr_probes * sizeof(void *)); |
| 123 | new[nr_probes] = probe; |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 124 | new[nr_probes + 1] = NULL; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 125 | entry->refcount = nr_probes + 1; |
| 126 | entry->funcs = new; |
| 127 | debug_print_probes(entry); |
| 128 | return old; |
| 129 | } |
| 130 | |
| 131 | static void * |
| 132 | tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe) |
| 133 | { |
| 134 | int nr_probes = 0, nr_del = 0, i; |
| 135 | void **old, **new; |
| 136 | |
| 137 | old = entry->funcs; |
| 138 | |
Frederic Weisbecker | f66af45 | 2008-10-22 19:14:55 +0200 | [diff] [blame] | 139 | if (!old) |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 140 | return ERR_PTR(-ENOENT); |
Frederic Weisbecker | f66af45 | 2008-10-22 19:14:55 +0200 | [diff] [blame] | 141 | |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 142 | debug_print_probes(entry); |
| 143 | /* (N -> M), (N > 1, M >= 0) probes */ |
| 144 | for (nr_probes = 0; old[nr_probes]; nr_probes++) { |
| 145 | if ((!probe || old[nr_probes] == probe)) |
| 146 | nr_del++; |
| 147 | } |
| 148 | |
| 149 | if (nr_probes - nr_del == 0) { |
| 150 | /* N -> 0, (N > 1) */ |
| 151 | entry->funcs = NULL; |
| 152 | entry->refcount = 0; |
| 153 | debug_print_probes(entry); |
| 154 | return old; |
| 155 | } else { |
| 156 | int j = 0; |
| 157 | /* N -> M, (N > 1, M > 0) */ |
| 158 | /* + 1 for NULL */ |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 159 | new = allocate_probes(nr_probes - nr_del + 1); |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 160 | if (new == NULL) |
| 161 | return ERR_PTR(-ENOMEM); |
| 162 | for (i = 0; old[i]; i++) |
| 163 | if ((probe && old[i] != probe)) |
| 164 | new[j++] = old[i]; |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 165 | new[nr_probes - nr_del] = NULL; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 166 | entry->refcount = nr_probes - nr_del; |
| 167 | entry->funcs = new; |
| 168 | } |
| 169 | debug_print_probes(entry); |
| 170 | return old; |
| 171 | } |
| 172 | |
| 173 | /* |
| 174 | * Get tracepoint if the tracepoint is present in the tracepoint hash table. |
| 175 | * Must be called with tracepoints_mutex held. |
| 176 | * Returns NULL if not present. |
| 177 | */ |
| 178 | static struct tracepoint_entry *get_tracepoint(const char *name) |
| 179 | { |
| 180 | struct hlist_head *head; |
| 181 | struct hlist_node *node; |
| 182 | struct tracepoint_entry *e; |
| 183 | u32 hash = jhash(name, strlen(name), 0); |
| 184 | |
Mathieu Desnoyers | 9795302 | 2008-07-24 16:37:23 -0400 | [diff] [blame] | 185 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 186 | hlist_for_each_entry(e, node, head, hlist) { |
| 187 | if (!strcmp(name, e->name)) |
| 188 | return e; |
| 189 | } |
| 190 | return NULL; |
| 191 | } |
| 192 | |
| 193 | /* |
| 194 | * Add the tracepoint to the tracepoint hash table. Must be called with |
| 195 | * tracepoints_mutex held. |
| 196 | */ |
| 197 | static struct tracepoint_entry *add_tracepoint(const char *name) |
| 198 | { |
| 199 | struct hlist_head *head; |
| 200 | struct hlist_node *node; |
| 201 | struct tracepoint_entry *e; |
| 202 | size_t name_len = strlen(name) + 1; |
| 203 | u32 hash = jhash(name, name_len-1, 0); |
| 204 | |
Mathieu Desnoyers | 9795302 | 2008-07-24 16:37:23 -0400 | [diff] [blame] | 205 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 206 | hlist_for_each_entry(e, node, head, hlist) { |
| 207 | if (!strcmp(name, e->name)) { |
| 208 | printk(KERN_NOTICE |
| 209 | "tracepoint %s busy\n", name); |
| 210 | return ERR_PTR(-EEXIST); /* Already there */ |
| 211 | } |
| 212 | } |
| 213 | /* |
| 214 | * Using kmalloc here to allocate a variable length element. Could |
| 215 | * cause some memory fragmentation if overused. |
| 216 | */ |
| 217 | e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL); |
| 218 | if (!e) |
| 219 | return ERR_PTR(-ENOMEM); |
| 220 | memcpy(&e->name[0], name, name_len); |
| 221 | e->funcs = NULL; |
| 222 | e->refcount = 0; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 223 | hlist_add_head(&e->hlist, head); |
| 224 | return e; |
| 225 | } |
| 226 | |
| 227 | /* |
| 228 | * Remove the tracepoint from the tracepoint hash table. Must be called with |
| 229 | * mutex_lock held. |
| 230 | */ |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 231 | static inline void remove_tracepoint(struct tracepoint_entry *e) |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 232 | { |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 233 | hlist_del(&e->hlist); |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 234 | kfree(e); |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 235 | } |
| 236 | |
| 237 | /* |
| 238 | * Sets the probe callback corresponding to one tracepoint. |
| 239 | */ |
| 240 | static void set_tracepoint(struct tracepoint_entry **entry, |
| 241 | struct tracepoint *elem, int active) |
| 242 | { |
| 243 | WARN_ON(strcmp((*entry)->name, elem->name) != 0); |
| 244 | |
| 245 | /* |
| 246 | * rcu_assign_pointer has a smp_wmb() which makes sure that the new |
| 247 | * probe callbacks array is consistent before setting a pointer to it. |
| 248 | * This array is referenced by __DO_TRACE from |
| 249 | * include/linux/tracepoints.h. A matching smp_read_barrier_depends() |
| 250 | * is used. |
| 251 | */ |
| 252 | rcu_assign_pointer(elem->funcs, (*entry)->funcs); |
| 253 | elem->state = active; |
| 254 | } |
| 255 | |
| 256 | /* |
| 257 | * Disable a tracepoint and its probe callback. |
| 258 | * Note: only waiting an RCU period after setting elem->call to the empty |
| 259 | * function insures that the original callback is not used anymore. This insured |
| 260 | * by preempt_disable around the call site. |
| 261 | */ |
| 262 | static void disable_tracepoint(struct tracepoint *elem) |
| 263 | { |
| 264 | elem->state = 0; |
Mathieu Desnoyers | de0baf9 | 2008-11-14 17:47:42 -0500 | [diff] [blame] | 265 | rcu_assign_pointer(elem->funcs, NULL); |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 266 | } |
| 267 | |
| 268 | /** |
| 269 | * tracepoint_update_probe_range - Update a probe range |
| 270 | * @begin: beginning of the range |
| 271 | * @end: end of the range |
| 272 | * |
| 273 | * Updates the probe callback corresponding to a range of tracepoints. |
| 274 | */ |
| 275 | void tracepoint_update_probe_range(struct tracepoint *begin, |
| 276 | struct tracepoint *end) |
| 277 | { |
| 278 | struct tracepoint *iter; |
| 279 | struct tracepoint_entry *mark_entry; |
| 280 | |
| 281 | mutex_lock(&tracepoints_mutex); |
| 282 | for (iter = begin; iter < end; iter++) { |
| 283 | mark_entry = get_tracepoint(iter->name); |
| 284 | if (mark_entry) { |
| 285 | set_tracepoint(&mark_entry, iter, |
| 286 | !!mark_entry->refcount); |
| 287 | } else { |
| 288 | disable_tracepoint(iter); |
| 289 | } |
| 290 | } |
| 291 | mutex_unlock(&tracepoints_mutex); |
| 292 | } |
| 293 | |
| 294 | /* |
| 295 | * Update probes, removing the faulty probes. |
| 296 | */ |
| 297 | static void tracepoint_update_probes(void) |
| 298 | { |
| 299 | /* Core kernel tracepoints */ |
| 300 | tracepoint_update_probe_range(__start___tracepoints, |
| 301 | __stop___tracepoints); |
| 302 | /* tracepoints in modules. */ |
| 303 | module_update_tracepoints(); |
| 304 | } |
| 305 | |
Lai Jiangshan | 127cafb | 2008-10-28 10:51:53 +0800 | [diff] [blame] | 306 | static void *tracepoint_add_probe(const char *name, void *probe) |
| 307 | { |
| 308 | struct tracepoint_entry *entry; |
| 309 | void *old; |
| 310 | |
| 311 | entry = get_tracepoint(name); |
| 312 | if (!entry) { |
| 313 | entry = add_tracepoint(name); |
| 314 | if (IS_ERR(entry)) |
| 315 | return entry; |
| 316 | } |
| 317 | old = tracepoint_entry_add_probe(entry, probe); |
| 318 | if (IS_ERR(old) && !entry->refcount) |
| 319 | remove_tracepoint(entry); |
| 320 | return old; |
| 321 | } |
| 322 | |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 323 | /** |
| 324 | * tracepoint_probe_register - Connect a probe to a tracepoint |
| 325 | * @name: tracepoint name |
| 326 | * @probe: probe handler |
| 327 | * |
| 328 | * Returns 0 if ok, error value on error. |
| 329 | * The probe address must at least be aligned on the architecture pointer size. |
| 330 | */ |
| 331 | int tracepoint_probe_register(const char *name, void *probe) |
| 332 | { |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 333 | void *old; |
| 334 | |
| 335 | mutex_lock(&tracepoints_mutex); |
Lai Jiangshan | 127cafb | 2008-10-28 10:51:53 +0800 | [diff] [blame] | 336 | old = tracepoint_add_probe(name, probe); |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 337 | mutex_unlock(&tracepoints_mutex); |
Lai Jiangshan | 127cafb | 2008-10-28 10:51:53 +0800 | [diff] [blame] | 338 | if (IS_ERR(old)) |
| 339 | return PTR_ERR(old); |
| 340 | |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 341 | tracepoint_update_probes(); /* may update entry */ |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 342 | release_probes(old); |
| 343 | return 0; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 344 | } |
| 345 | EXPORT_SYMBOL_GPL(tracepoint_probe_register); |
| 346 | |
Lai Jiangshan | 127cafb | 2008-10-28 10:51:53 +0800 | [diff] [blame] | 347 | static void *tracepoint_remove_probe(const char *name, void *probe) |
| 348 | { |
| 349 | struct tracepoint_entry *entry; |
| 350 | void *old; |
| 351 | |
| 352 | entry = get_tracepoint(name); |
| 353 | if (!entry) |
| 354 | return ERR_PTR(-ENOENT); |
| 355 | old = tracepoint_entry_remove_probe(entry, probe); |
| 356 | if (IS_ERR(old)) |
| 357 | return old; |
| 358 | if (!entry->refcount) |
| 359 | remove_tracepoint(entry); |
| 360 | return old; |
| 361 | } |
| 362 | |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 363 | /** |
| 364 | * tracepoint_probe_unregister - Disconnect a probe from a tracepoint |
| 365 | * @name: tracepoint name |
| 366 | * @probe: probe function pointer |
| 367 | * |
| 368 | * We do not need to call a synchronize_sched to make sure the probes have |
| 369 | * finished running before doing a module unload, because the module unload |
| 370 | * itself uses stop_machine(), which insures that every preempt disabled section |
| 371 | * have finished. |
| 372 | */ |
| 373 | int tracepoint_probe_unregister(const char *name, void *probe) |
| 374 | { |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 375 | void *old; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 376 | |
| 377 | mutex_lock(&tracepoints_mutex); |
Lai Jiangshan | 127cafb | 2008-10-28 10:51:53 +0800 | [diff] [blame] | 378 | old = tracepoint_remove_probe(name, probe); |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 379 | mutex_unlock(&tracepoints_mutex); |
Lai Jiangshan | 127cafb | 2008-10-28 10:51:53 +0800 | [diff] [blame] | 380 | if (IS_ERR(old)) |
| 381 | return PTR_ERR(old); |
| 382 | |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 383 | tracepoint_update_probes(); /* may update entry */ |
Lai Jiangshan | 19dba33 | 2008-10-28 10:51:49 +0800 | [diff] [blame] | 384 | release_probes(old); |
| 385 | return 0; |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 386 | } |
| 387 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); |
| 388 | |
Lai Jiangshan | 127cafb | 2008-10-28 10:51:53 +0800 | [diff] [blame] | 389 | static LIST_HEAD(old_probes); |
| 390 | static int need_update; |
| 391 | |
| 392 | static void tracepoint_add_old_probes(void *old) |
| 393 | { |
| 394 | need_update = 1; |
| 395 | if (old) { |
| 396 | struct tp_probes *tp_probes = container_of(old, |
| 397 | struct tp_probes, probes[0]); |
| 398 | list_add(&tp_probes->u.list, &old_probes); |
| 399 | } |
| 400 | } |
| 401 | |
| 402 | /** |
| 403 | * tracepoint_probe_register_noupdate - register a probe but not connect |
| 404 | * @name: tracepoint name |
| 405 | * @probe: probe handler |
| 406 | * |
| 407 | * caller must call tracepoint_probe_update_all() |
| 408 | */ |
| 409 | int tracepoint_probe_register_noupdate(const char *name, void *probe) |
| 410 | { |
| 411 | void *old; |
| 412 | |
| 413 | mutex_lock(&tracepoints_mutex); |
| 414 | old = tracepoint_add_probe(name, probe); |
| 415 | if (IS_ERR(old)) { |
| 416 | mutex_unlock(&tracepoints_mutex); |
| 417 | return PTR_ERR(old); |
| 418 | } |
| 419 | tracepoint_add_old_probes(old); |
| 420 | mutex_unlock(&tracepoints_mutex); |
| 421 | return 0; |
| 422 | } |
| 423 | EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate); |
| 424 | |
| 425 | /** |
| 426 | * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect |
| 427 | * @name: tracepoint name |
| 428 | * @probe: probe function pointer |
| 429 | * |
| 430 | * caller must call tracepoint_probe_update_all() |
| 431 | */ |
| 432 | int tracepoint_probe_unregister_noupdate(const char *name, void *probe) |
| 433 | { |
| 434 | void *old; |
| 435 | |
| 436 | mutex_lock(&tracepoints_mutex); |
| 437 | old = tracepoint_remove_probe(name, probe); |
| 438 | if (IS_ERR(old)) { |
| 439 | mutex_unlock(&tracepoints_mutex); |
| 440 | return PTR_ERR(old); |
| 441 | } |
| 442 | tracepoint_add_old_probes(old); |
| 443 | mutex_unlock(&tracepoints_mutex); |
| 444 | return 0; |
| 445 | } |
| 446 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate); |
| 447 | |
| 448 | /** |
| 449 | * tracepoint_probe_update_all - update tracepoints |
| 450 | */ |
| 451 | void tracepoint_probe_update_all(void) |
| 452 | { |
| 453 | LIST_HEAD(release_probes); |
| 454 | struct tp_probes *pos, *next; |
| 455 | |
| 456 | mutex_lock(&tracepoints_mutex); |
| 457 | if (!need_update) { |
| 458 | mutex_unlock(&tracepoints_mutex); |
| 459 | return; |
| 460 | } |
| 461 | if (!list_empty(&old_probes)) |
| 462 | list_replace_init(&old_probes, &release_probes); |
| 463 | need_update = 0; |
| 464 | mutex_unlock(&tracepoints_mutex); |
| 465 | |
| 466 | tracepoint_update_probes(); |
| 467 | list_for_each_entry_safe(pos, next, &release_probes, u.list) { |
| 468 | list_del(&pos->u.list); |
| 469 | call_rcu_sched(&pos->u.rcu, rcu_free_old_probes); |
| 470 | } |
| 471 | } |
| 472 | EXPORT_SYMBOL_GPL(tracepoint_probe_update_all); |
| 473 | |
Mathieu Desnoyers | 97e1c18 | 2008-07-18 12:16:16 -0400 | [diff] [blame] | 474 | /** |
| 475 | * tracepoint_get_iter_range - Get a next tracepoint iterator given a range. |
| 476 | * @tracepoint: current tracepoints (in), next tracepoint (out) |
| 477 | * @begin: beginning of the range |
| 478 | * @end: end of the range |
| 479 | * |
| 480 | * Returns whether a next tracepoint has been found (1) or not (0). |
| 481 | * Will return the first tracepoint in the range if the input tracepoint is |
| 482 | * NULL. |
| 483 | */ |
| 484 | int tracepoint_get_iter_range(struct tracepoint **tracepoint, |
| 485 | struct tracepoint *begin, struct tracepoint *end) |
| 486 | { |
| 487 | if (!*tracepoint && begin != end) { |
| 488 | *tracepoint = begin; |
| 489 | return 1; |
| 490 | } |
| 491 | if (*tracepoint >= begin && *tracepoint < end) |
| 492 | return 1; |
| 493 | return 0; |
| 494 | } |
| 495 | EXPORT_SYMBOL_GPL(tracepoint_get_iter_range); |
| 496 | |
| 497 | static void tracepoint_get_iter(struct tracepoint_iter *iter) |
| 498 | { |
| 499 | int found = 0; |
| 500 | |
| 501 | /* Core kernel tracepoints */ |
| 502 | if (!iter->module) { |
| 503 | found = tracepoint_get_iter_range(&iter->tracepoint, |
| 504 | __start___tracepoints, __stop___tracepoints); |
| 505 | if (found) |
| 506 | goto end; |
| 507 | } |
| 508 | /* tracepoints in modules. */ |
| 509 | found = module_get_iter_tracepoints(iter); |
| 510 | end: |
| 511 | if (!found) |
| 512 | tracepoint_iter_reset(iter); |
| 513 | } |
| 514 | |
| 515 | void tracepoint_iter_start(struct tracepoint_iter *iter) |
| 516 | { |
| 517 | tracepoint_get_iter(iter); |
| 518 | } |
| 519 | EXPORT_SYMBOL_GPL(tracepoint_iter_start); |
| 520 | |
| 521 | void tracepoint_iter_next(struct tracepoint_iter *iter) |
| 522 | { |
| 523 | iter->tracepoint++; |
| 524 | /* |
| 525 | * iter->tracepoint may be invalid because we blindly incremented it. |
| 526 | * Make sure it is valid by marshalling on the tracepoints, getting the |
| 527 | * tracepoints from following modules if necessary. |
| 528 | */ |
| 529 | tracepoint_get_iter(iter); |
| 530 | } |
| 531 | EXPORT_SYMBOL_GPL(tracepoint_iter_next); |
| 532 | |
| 533 | void tracepoint_iter_stop(struct tracepoint_iter *iter) |
| 534 | { |
| 535 | } |
| 536 | EXPORT_SYMBOL_GPL(tracepoint_iter_stop); |
| 537 | |
| 538 | void tracepoint_iter_reset(struct tracepoint_iter *iter) |
| 539 | { |
| 540 | iter->module = NULL; |
| 541 | iter->tracepoint = NULL; |
| 542 | } |
| 543 | EXPORT_SYMBOL_GPL(tracepoint_iter_reset); |
Mathieu Desnoyers | 32f8574 | 2008-11-14 17:47:46 -0500 | [diff] [blame] | 544 | |
Ingo Molnar | 227a837 | 2008-11-16 09:50:34 +0100 | [diff] [blame] | 545 | #ifdef CONFIG_MODULES |
| 546 | |
Mathieu Desnoyers | 32f8574 | 2008-11-14 17:47:46 -0500 | [diff] [blame] | 547 | int tracepoint_module_notify(struct notifier_block *self, |
| 548 | unsigned long val, void *data) |
| 549 | { |
| 550 | struct module *mod = data; |
| 551 | |
| 552 | switch (val) { |
| 553 | case MODULE_STATE_COMING: |
| 554 | tracepoint_update_probe_range(mod->tracepoints, |
| 555 | mod->tracepoints + mod->num_tracepoints); |
| 556 | break; |
| 557 | case MODULE_STATE_GOING: |
| 558 | tracepoint_update_probe_range(mod->tracepoints, |
| 559 | mod->tracepoints + mod->num_tracepoints); |
| 560 | break; |
| 561 | } |
| 562 | return 0; |
| 563 | } |
| 564 | |
| 565 | struct notifier_block tracepoint_module_nb = { |
| 566 | .notifier_call = tracepoint_module_notify, |
| 567 | .priority = 0, |
| 568 | }; |
| 569 | |
| 570 | static int init_tracepoints(void) |
| 571 | { |
| 572 | return register_module_notifier(&tracepoint_module_nb); |
| 573 | } |
| 574 | __initcall(init_tracepoints); |
Ingo Molnar | 227a837 | 2008-11-16 09:50:34 +0100 | [diff] [blame] | 575 | |
| 576 | #endif /* CONFIG_MODULES */ |