sh: Add support Renesas Solutions AP-325RXA board
[linux-2.6/pdupreez.git] / kernel / marker.c
blob971da531790316bbe4bff400d7dec77e46c76a42
1 /*
2 * Copyright (C) 2007 Mathieu Desnoyers
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.
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.
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.
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/marker.h>
25 #include <linux/err.h>
26 #include <linux/slab.h>
28 extern struct marker __start___markers[];
29 extern struct marker __stop___markers[];
31 /* Set to 1 to enable marker debug output */
32 static const int marker_debug;
35 * markers_mutex nests inside module_mutex. Markers mutex protects the builtin
36 * and module markers and the hash table.
38 static DEFINE_MUTEX(markers_mutex);
41 * Marker hash table, containing the active markers.
42 * Protected by module_mutex.
44 #define MARKER_HASH_BITS 6
45 #define MARKER_TABLE_SIZE (1 << MARKER_HASH_BITS)
48 * Note about RCU :
49 * It is used to make sure every handler has finished using its private data
50 * between two consecutive operation (add or remove) on a given marker. It is
51 * also used to delay the free of multiple probes array until a quiescent state
52 * is reached.
53 * marker entries modifications are protected by the markers_mutex.
55 struct marker_entry {
56 struct hlist_node hlist;
57 char *format;
58 /* Probe wrapper */
59 void (*call)(const struct marker *mdata, void *call_private, ...);
60 struct marker_probe_closure single;
61 struct marker_probe_closure *multi;
62 int refcount; /* Number of times armed. 0 if disarmed. */
63 struct rcu_head rcu;
64 void *oldptr;
65 unsigned char rcu_pending:1;
66 unsigned char ptype:1;
67 char name[0]; /* Contains name'\0'format'\0' */
70 static struct hlist_head marker_table[MARKER_TABLE_SIZE];
72 /**
73 * __mark_empty_function - Empty probe callback
74 * @probe_private: probe private data
75 * @call_private: call site private data
76 * @fmt: format string
77 * @...: variable argument list
79 * Empty callback provided as a probe to the markers. By providing this to a
80 * disabled marker, we make sure the execution flow is always valid even
81 * though the function pointer change and the marker enabling are two distinct
82 * operations that modifies the execution flow of preemptible code.
84 void __mark_empty_function(void *probe_private, void *call_private,
85 const char *fmt, va_list *args)
88 EXPORT_SYMBOL_GPL(__mark_empty_function);
91 * marker_probe_cb Callback that prepares the variable argument list for probes.
92 * @mdata: pointer of type struct marker
93 * @call_private: caller site private data
94 * @...: Variable argument list.
96 * Since we do not use "typical" pointer based RCU in the 1 argument case, we
97 * need to put a full smp_rmb() in this branch. This is why we do not use
98 * rcu_dereference() for the pointer read.
100 void marker_probe_cb(const struct marker *mdata, void *call_private, ...)
102 va_list args;
103 char ptype;
106 * preempt_disable does two things : disabling preemption to make sure
107 * the teardown of the callbacks can be done correctly when they are in
108 * modules and they insure RCU read coherency.
110 preempt_disable();
111 ptype = mdata->ptype;
112 if (likely(!ptype)) {
113 marker_probe_func *func;
114 /* Must read the ptype before ptr. They are not data dependant,
115 * so we put an explicit smp_rmb() here. */
116 smp_rmb();
117 func = mdata->single.func;
118 /* Must read the ptr before private data. They are not data
119 * dependant, so we put an explicit smp_rmb() here. */
120 smp_rmb();
121 va_start(args, call_private);
122 func(mdata->single.probe_private, call_private, mdata->format,
123 &args);
124 va_end(args);
125 } else {
126 struct marker_probe_closure *multi;
127 int i;
129 * multi points to an array, therefore accessing the array
130 * depends on reading multi. However, even in this case,
131 * we must insure that the pointer is read _before_ the array
132 * data. Same as rcu_dereference, but we need a full smp_rmb()
133 * in the fast path, so put the explicit barrier here.
135 smp_read_barrier_depends();
136 multi = mdata->multi;
137 for (i = 0; multi[i].func; i++) {
138 va_start(args, call_private);
139 multi[i].func(multi[i].probe_private, call_private,
140 mdata->format, &args);
141 va_end(args);
144 preempt_enable();
146 EXPORT_SYMBOL_GPL(marker_probe_cb);
149 * marker_probe_cb Callback that does not prepare the variable argument list.
150 * @mdata: pointer of type struct marker
151 * @call_private: caller site private data
152 * @...: Variable argument list.
154 * Should be connected to markers "MARK_NOARGS".
156 void marker_probe_cb_noarg(const struct marker *mdata, void *call_private, ...)
158 va_list args; /* not initialized */
159 char ptype;
161 preempt_disable();
162 ptype = mdata->ptype;
163 if (likely(!ptype)) {
164 marker_probe_func *func;
165 /* Must read the ptype before ptr. They are not data dependant,
166 * so we put an explicit smp_rmb() here. */
167 smp_rmb();
168 func = mdata->single.func;
169 /* Must read the ptr before private data. They are not data
170 * dependant, so we put an explicit smp_rmb() here. */
171 smp_rmb();
172 func(mdata->single.probe_private, call_private, mdata->format,
173 &args);
174 } else {
175 struct marker_probe_closure *multi;
176 int i;
178 * multi points to an array, therefore accessing the array
179 * depends on reading multi. However, even in this case,
180 * we must insure that the pointer is read _before_ the array
181 * data. Same as rcu_dereference, but we need a full smp_rmb()
182 * in the fast path, so put the explicit barrier here.
184 smp_read_barrier_depends();
185 multi = mdata->multi;
186 for (i = 0; multi[i].func; i++)
187 multi[i].func(multi[i].probe_private, call_private,
188 mdata->format, &args);
190 preempt_enable();
192 EXPORT_SYMBOL_GPL(marker_probe_cb_noarg);
194 static void free_old_closure(struct rcu_head *head)
196 struct marker_entry *entry = container_of(head,
197 struct marker_entry, rcu);
198 kfree(entry->oldptr);
199 /* Make sure we free the data before setting the pending flag to 0 */
200 smp_wmb();
201 entry->rcu_pending = 0;
204 static void debug_print_probes(struct marker_entry *entry)
206 int i;
208 if (!marker_debug)
209 return;
211 if (!entry->ptype) {
212 printk(KERN_DEBUG "Single probe : %p %p\n",
213 entry->single.func,
214 entry->single.probe_private);
215 } else {
216 for (i = 0; entry->multi[i].func; i++)
217 printk(KERN_DEBUG "Multi probe %d : %p %p\n", i,
218 entry->multi[i].func,
219 entry->multi[i].probe_private);
223 static struct marker_probe_closure *
224 marker_entry_add_probe(struct marker_entry *entry,
225 marker_probe_func *probe, void *probe_private)
227 int nr_probes = 0;
228 struct marker_probe_closure *old, *new;
230 WARN_ON(!probe);
232 debug_print_probes(entry);
233 old = entry->multi;
234 if (!entry->ptype) {
235 if (entry->single.func == probe &&
236 entry->single.probe_private == probe_private)
237 return ERR_PTR(-EBUSY);
238 if (entry->single.func == __mark_empty_function) {
239 /* 0 -> 1 probes */
240 entry->single.func = probe;
241 entry->single.probe_private = probe_private;
242 entry->refcount = 1;
243 entry->ptype = 0;
244 debug_print_probes(entry);
245 return NULL;
246 } else {
247 /* 1 -> 2 probes */
248 nr_probes = 1;
249 old = NULL;
251 } else {
252 /* (N -> N+1), (N != 0, 1) probes */
253 for (nr_probes = 0; old[nr_probes].func; nr_probes++)
254 if (old[nr_probes].func == probe
255 && old[nr_probes].probe_private
256 == probe_private)
257 return ERR_PTR(-EBUSY);
259 /* + 2 : one for new probe, one for NULL func */
260 new = kzalloc((nr_probes + 2) * sizeof(struct marker_probe_closure),
261 GFP_KERNEL);
262 if (new == NULL)
263 return ERR_PTR(-ENOMEM);
264 if (!old)
265 new[0] = entry->single;
266 else
267 memcpy(new, old,
268 nr_probes * sizeof(struct marker_probe_closure));
269 new[nr_probes].func = probe;
270 new[nr_probes].probe_private = probe_private;
271 entry->refcount = nr_probes + 1;
272 entry->multi = new;
273 entry->ptype = 1;
274 debug_print_probes(entry);
275 return old;
278 static struct marker_probe_closure *
279 marker_entry_remove_probe(struct marker_entry *entry,
280 marker_probe_func *probe, void *probe_private)
282 int nr_probes = 0, nr_del = 0, i;
283 struct marker_probe_closure *old, *new;
285 old = entry->multi;
287 debug_print_probes(entry);
288 if (!entry->ptype) {
289 /* 0 -> N is an error */
290 WARN_ON(entry->single.func == __mark_empty_function);
291 /* 1 -> 0 probes */
292 WARN_ON(probe && entry->single.func != probe);
293 WARN_ON(entry->single.probe_private != probe_private);
294 entry->single.func = __mark_empty_function;
295 entry->refcount = 0;
296 entry->ptype = 0;
297 debug_print_probes(entry);
298 return NULL;
299 } else {
300 /* (N -> M), (N > 1, M >= 0) probes */
301 for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
302 if ((!probe || old[nr_probes].func == probe)
303 && old[nr_probes].probe_private
304 == probe_private)
305 nr_del++;
309 if (nr_probes - nr_del == 0) {
310 /* N -> 0, (N > 1) */
311 entry->single.func = __mark_empty_function;
312 entry->refcount = 0;
313 entry->ptype = 0;
314 } else if (nr_probes - nr_del == 1) {
315 /* N -> 1, (N > 1) */
316 for (i = 0; old[i].func; i++)
317 if ((probe && old[i].func != probe) ||
318 old[i].probe_private != probe_private)
319 entry->single = old[i];
320 entry->refcount = 1;
321 entry->ptype = 0;
322 } else {
323 int j = 0;
324 /* N -> M, (N > 1, M > 1) */
325 /* + 1 for NULL */
326 new = kzalloc((nr_probes - nr_del + 1)
327 * sizeof(struct marker_probe_closure), GFP_KERNEL);
328 if (new == NULL)
329 return ERR_PTR(-ENOMEM);
330 for (i = 0; old[i].func; i++)
331 if ((probe && old[i].func != probe) ||
332 old[i].probe_private != probe_private)
333 new[j++] = old[i];
334 entry->refcount = nr_probes - nr_del;
335 entry->ptype = 1;
336 entry->multi = new;
338 debug_print_probes(entry);
339 return old;
343 * Get marker if the marker is present in the marker hash table.
344 * Must be called with markers_mutex held.
345 * Returns NULL if not present.
347 static struct marker_entry *get_marker(const char *name)
349 struct hlist_head *head;
350 struct hlist_node *node;
351 struct marker_entry *e;
352 u32 hash = jhash(name, strlen(name), 0);
354 head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
355 hlist_for_each_entry(e, node, head, hlist) {
356 if (!strcmp(name, e->name))
357 return e;
359 return NULL;
363 * Add the marker to the marker hash table. Must be called with markers_mutex
364 * held.
366 static struct marker_entry *add_marker(const char *name, const char *format)
368 struct hlist_head *head;
369 struct hlist_node *node;
370 struct marker_entry *e;
371 size_t name_len = strlen(name) + 1;
372 size_t format_len = 0;
373 u32 hash = jhash(name, name_len-1, 0);
375 if (format)
376 format_len = strlen(format) + 1;
377 head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
378 hlist_for_each_entry(e, node, head, hlist) {
379 if (!strcmp(name, e->name)) {
380 printk(KERN_NOTICE
381 "Marker %s busy\n", name);
382 return ERR_PTR(-EBUSY); /* Already there */
386 * Using kmalloc here to allocate a variable length element. Could
387 * cause some memory fragmentation if overused.
389 e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
390 GFP_KERNEL);
391 if (!e)
392 return ERR_PTR(-ENOMEM);
393 memcpy(&e->name[0], name, name_len);
394 if (format) {
395 e->format = &e->name[name_len];
396 memcpy(e->format, format, format_len);
397 if (strcmp(e->format, MARK_NOARGS) == 0)
398 e->call = marker_probe_cb_noarg;
399 else
400 e->call = marker_probe_cb;
401 trace_mark(core_marker_format, "name %s format %s",
402 e->name, e->format);
403 } else {
404 e->format = NULL;
405 e->call = marker_probe_cb;
407 e->single.func = __mark_empty_function;
408 e->single.probe_private = NULL;
409 e->multi = NULL;
410 e->ptype = 0;
411 e->refcount = 0;
412 e->rcu_pending = 0;
413 hlist_add_head(&e->hlist, head);
414 return e;
418 * Remove the marker from the marker hash table. Must be called with mutex_lock
419 * held.
421 static int remove_marker(const char *name)
423 struct hlist_head *head;
424 struct hlist_node *node;
425 struct marker_entry *e;
426 int found = 0;
427 size_t len = strlen(name) + 1;
428 u32 hash = jhash(name, len-1, 0);
430 head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
431 hlist_for_each_entry(e, node, head, hlist) {
432 if (!strcmp(name, e->name)) {
433 found = 1;
434 break;
437 if (!found)
438 return -ENOENT;
439 if (e->single.func != __mark_empty_function)
440 return -EBUSY;
441 hlist_del(&e->hlist);
442 /* Make sure the call_rcu has been executed */
443 if (e->rcu_pending)
444 rcu_barrier_sched();
445 kfree(e);
446 return 0;
450 * Set the mark_entry format to the format found in the element.
452 static int marker_set_format(struct marker_entry **entry, const char *format)
454 struct marker_entry *e;
455 size_t name_len = strlen((*entry)->name) + 1;
456 size_t format_len = strlen(format) + 1;
459 e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
460 GFP_KERNEL);
461 if (!e)
462 return -ENOMEM;
463 memcpy(&e->name[0], (*entry)->name, name_len);
464 e->format = &e->name[name_len];
465 memcpy(e->format, format, format_len);
466 if (strcmp(e->format, MARK_NOARGS) == 0)
467 e->call = marker_probe_cb_noarg;
468 else
469 e->call = marker_probe_cb;
470 e->single = (*entry)->single;
471 e->multi = (*entry)->multi;
472 e->ptype = (*entry)->ptype;
473 e->refcount = (*entry)->refcount;
474 e->rcu_pending = 0;
475 hlist_add_before(&e->hlist, &(*entry)->hlist);
476 hlist_del(&(*entry)->hlist);
477 /* Make sure the call_rcu has been executed */
478 if ((*entry)->rcu_pending)
479 rcu_barrier_sched();
480 kfree(*entry);
481 *entry = e;
482 trace_mark(core_marker_format, "name %s format %s",
483 e->name, e->format);
484 return 0;
488 * Sets the probe callback corresponding to one marker.
490 static int set_marker(struct marker_entry **entry, struct marker *elem,
491 int active)
493 int ret;
494 WARN_ON(strcmp((*entry)->name, elem->name) != 0);
496 if ((*entry)->format) {
497 if (strcmp((*entry)->format, elem->format) != 0) {
498 printk(KERN_NOTICE
499 "Format mismatch for probe %s "
500 "(%s), marker (%s)\n",
501 (*entry)->name,
502 (*entry)->format,
503 elem->format);
504 return -EPERM;
506 } else {
507 ret = marker_set_format(entry, elem->format);
508 if (ret)
509 return ret;
513 * probe_cb setup (statically known) is done here. It is
514 * asynchronous with the rest of execution, therefore we only
515 * pass from a "safe" callback (with argument) to an "unsafe"
516 * callback (does not set arguments).
518 elem->call = (*entry)->call;
520 * Sanity check :
521 * We only update the single probe private data when the ptr is
522 * set to a _non_ single probe! (0 -> 1 and N -> 1, N != 1)
524 WARN_ON(elem->single.func != __mark_empty_function
525 && elem->single.probe_private
526 != (*entry)->single.probe_private &&
527 !elem->ptype);
528 elem->single.probe_private = (*entry)->single.probe_private;
530 * Make sure the private data is valid when we update the
531 * single probe ptr.
533 smp_wmb();
534 elem->single.func = (*entry)->single.func;
536 * We also make sure that the new probe callbacks array is consistent
537 * before setting a pointer to it.
539 rcu_assign_pointer(elem->multi, (*entry)->multi);
541 * Update the function or multi probe array pointer before setting the
542 * ptype.
544 smp_wmb();
545 elem->ptype = (*entry)->ptype;
546 elem->state = active;
548 return 0;
552 * Disable a marker and its probe callback.
553 * Note: only waiting an RCU period after setting elem->call to the empty
554 * function insures that the original callback is not used anymore. This insured
555 * by preempt_disable around the call site.
557 static void disable_marker(struct marker *elem)
559 /* leave "call" as is. It is known statically. */
560 elem->state = 0;
561 elem->single.func = __mark_empty_function;
562 /* Update the function before setting the ptype */
563 smp_wmb();
564 elem->ptype = 0; /* single probe */
566 * Leave the private data and id there, because removal is racy and
567 * should be done only after an RCU period. These are never used until
568 * the next initialization anyway.
573 * marker_update_probe_range - Update a probe range
574 * @begin: beginning of the range
575 * @end: end of the range
577 * Updates the probe callback corresponding to a range of markers.
579 void marker_update_probe_range(struct marker *begin,
580 struct marker *end)
582 struct marker *iter;
583 struct marker_entry *mark_entry;
585 mutex_lock(&markers_mutex);
586 for (iter = begin; iter < end; iter++) {
587 mark_entry = get_marker(iter->name);
588 if (mark_entry) {
589 set_marker(&mark_entry, iter,
590 !!mark_entry->refcount);
592 * ignore error, continue
594 } else {
595 disable_marker(iter);
598 mutex_unlock(&markers_mutex);
602 * Update probes, removing the faulty probes.
604 * Internal callback only changed before the first probe is connected to it.
605 * Single probe private data can only be changed on 0 -> 1 and 2 -> 1
606 * transitions. All other transitions will leave the old private data valid.
607 * This makes the non-atomicity of the callback/private data updates valid.
609 * "special case" updates :
610 * 0 -> 1 callback
611 * 1 -> 0 callback
612 * 1 -> 2 callbacks
613 * 2 -> 1 callbacks
614 * Other updates all behave the same, just like the 2 -> 3 or 3 -> 2 updates.
615 * Site effect : marker_set_format may delete the marker entry (creating a
616 * replacement).
618 static void marker_update_probes(void)
620 /* Core kernel markers */
621 marker_update_probe_range(__start___markers, __stop___markers);
622 /* Markers in modules. */
623 module_update_markers();
627 * marker_probe_register - Connect a probe to a marker
628 * @name: marker name
629 * @format: format string
630 * @probe: probe handler
631 * @probe_private: probe private data
633 * private data must be a valid allocated memory address, or NULL.
634 * Returns 0 if ok, error value on error.
635 * The probe address must at least be aligned on the architecture pointer size.
637 int marker_probe_register(const char *name, const char *format,
638 marker_probe_func *probe, void *probe_private)
640 struct marker_entry *entry;
641 int ret = 0;
642 struct marker_probe_closure *old;
644 mutex_lock(&markers_mutex);
645 entry = get_marker(name);
646 if (!entry) {
647 entry = add_marker(name, format);
648 if (IS_ERR(entry)) {
649 ret = PTR_ERR(entry);
650 goto end;
654 * If we detect that a call_rcu is pending for this marker,
655 * make sure it's executed now.
657 if (entry->rcu_pending)
658 rcu_barrier_sched();
659 old = marker_entry_add_probe(entry, probe, probe_private);
660 if (IS_ERR(old)) {
661 ret = PTR_ERR(old);
662 goto end;
664 mutex_unlock(&markers_mutex);
665 marker_update_probes(); /* may update entry */
666 mutex_lock(&markers_mutex);
667 entry = get_marker(name);
668 WARN_ON(!entry);
669 entry->oldptr = old;
670 entry->rcu_pending = 1;
671 /* write rcu_pending before calling the RCU callback */
672 smp_wmb();
673 call_rcu_sched(&entry->rcu, free_old_closure);
674 end:
675 mutex_unlock(&markers_mutex);
676 return ret;
678 EXPORT_SYMBOL_GPL(marker_probe_register);
681 * marker_probe_unregister - Disconnect a probe from a marker
682 * @name: marker name
683 * @probe: probe function pointer
684 * @probe_private: probe private data
686 * Returns the private data given to marker_probe_register, or an ERR_PTR().
687 * We do not need to call a synchronize_sched to make sure the probes have
688 * finished running before doing a module unload, because the module unload
689 * itself uses stop_machine(), which insures that every preempt disabled section
690 * have finished.
692 int marker_probe_unregister(const char *name,
693 marker_probe_func *probe, void *probe_private)
695 struct marker_entry *entry;
696 struct marker_probe_closure *old;
697 int ret = -ENOENT;
699 mutex_lock(&markers_mutex);
700 entry = get_marker(name);
701 if (!entry)
702 goto end;
703 if (entry->rcu_pending)
704 rcu_barrier_sched();
705 old = marker_entry_remove_probe(entry, probe, probe_private);
706 mutex_unlock(&markers_mutex);
707 marker_update_probes(); /* may update entry */
708 mutex_lock(&markers_mutex);
709 entry = get_marker(name);
710 if (!entry)
711 goto end;
712 entry->oldptr = old;
713 entry->rcu_pending = 1;
714 /* write rcu_pending before calling the RCU callback */
715 smp_wmb();
716 call_rcu_sched(&entry->rcu, free_old_closure);
717 remove_marker(name); /* Ignore busy error message */
718 ret = 0;
719 end:
720 mutex_unlock(&markers_mutex);
721 return ret;
723 EXPORT_SYMBOL_GPL(marker_probe_unregister);
725 static struct marker_entry *
726 get_marker_from_private_data(marker_probe_func *probe, void *probe_private)
728 struct marker_entry *entry;
729 unsigned int i;
730 struct hlist_head *head;
731 struct hlist_node *node;
733 for (i = 0; i < MARKER_TABLE_SIZE; i++) {
734 head = &marker_table[i];
735 hlist_for_each_entry(entry, node, head, hlist) {
736 if (!entry->ptype) {
737 if (entry->single.func == probe
738 && entry->single.probe_private
739 == probe_private)
740 return entry;
741 } else {
742 struct marker_probe_closure *closure;
743 closure = entry->multi;
744 for (i = 0; closure[i].func; i++) {
745 if (closure[i].func == probe &&
746 closure[i].probe_private
747 == probe_private)
748 return entry;
753 return NULL;
757 * marker_probe_unregister_private_data - Disconnect a probe from a marker
758 * @probe: probe function
759 * @probe_private: probe private data
761 * Unregister a probe by providing the registered private data.
762 * Only removes the first marker found in hash table.
763 * Return 0 on success or error value.
764 * We do not need to call a synchronize_sched to make sure the probes have
765 * finished running before doing a module unload, because the module unload
766 * itself uses stop_machine(), which insures that every preempt disabled section
767 * have finished.
769 int marker_probe_unregister_private_data(marker_probe_func *probe,
770 void *probe_private)
772 struct marker_entry *entry;
773 int ret = 0;
774 struct marker_probe_closure *old;
776 mutex_lock(&markers_mutex);
777 entry = get_marker_from_private_data(probe, probe_private);
778 if (!entry) {
779 ret = -ENOENT;
780 goto end;
782 if (entry->rcu_pending)
783 rcu_barrier_sched();
784 old = marker_entry_remove_probe(entry, NULL, probe_private);
785 mutex_unlock(&markers_mutex);
786 marker_update_probes(); /* may update entry */
787 mutex_lock(&markers_mutex);
788 entry = get_marker_from_private_data(probe, probe_private);
789 WARN_ON(!entry);
790 entry->oldptr = old;
791 entry->rcu_pending = 1;
792 /* write rcu_pending before calling the RCU callback */
793 smp_wmb();
794 call_rcu_sched(&entry->rcu, free_old_closure);
795 remove_marker(entry->name); /* Ignore busy error message */
796 end:
797 mutex_unlock(&markers_mutex);
798 return ret;
800 EXPORT_SYMBOL_GPL(marker_probe_unregister_private_data);
803 * marker_get_private_data - Get a marker's probe private data
804 * @name: marker name
805 * @probe: probe to match
806 * @num: get the nth matching probe's private data
808 * Returns the nth private data pointer (starting from 0) matching, or an
809 * ERR_PTR.
810 * Returns the private data pointer, or an ERR_PTR.
811 * The private data pointer should _only_ be dereferenced if the caller is the
812 * owner of the data, or its content could vanish. This is mostly used to
813 * confirm that a caller is the owner of a registered probe.
815 void *marker_get_private_data(const char *name, marker_probe_func *probe,
816 int num)
818 struct hlist_head *head;
819 struct hlist_node *node;
820 struct marker_entry *e;
821 size_t name_len = strlen(name) + 1;
822 u32 hash = jhash(name, name_len-1, 0);
823 int i;
825 head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
826 hlist_for_each_entry(e, node, head, hlist) {
827 if (!strcmp(name, e->name)) {
828 if (!e->ptype) {
829 if (num == 0 && e->single.func == probe)
830 return e->single.probe_private;
831 else
832 break;
833 } else {
834 struct marker_probe_closure *closure;
835 int match = 0;
836 closure = e->multi;
837 for (i = 0; closure[i].func; i++) {
838 if (closure[i].func != probe)
839 continue;
840 if (match++ == num)
841 return closure[i].probe_private;
846 return ERR_PTR(-ENOENT);
848 EXPORT_SYMBOL_GPL(marker_get_private_data);