1 From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
   2 
   3 RCU style multiple probes support for the Linux Kernel Markers.  Common case
   4 (one probe) is still fast and does not require dynamic allocation or a
   5 supplementary pointer dereference on the fast path.
   6 
   7 - Move preempt disable from the marker site to the callback.
   8 
   9 Since we now have an internal callback, move the preempt disable/enable to the
  10 callback instead of the marker site.
  11 
  12 Since the callback change is done asynchronously (passing from a handler that
  13 supports arguments to a handler that does not setup the arguments is no
  14 arguments are passed), we can safely update it even if it is outside the
  15 preempt disable section.
  16 
  17 - Move probe arm to probe connection. Now, a connected probe is automatically
  18   armed.
  19 
  20 Remove MARK_MAX_FORMAT_LEN, unused.
  21 
  22 This patch modifies the Linux Kernel Markers API : it removes the probe
  23 "arm/disarm" and changes the probe function prototype : it now expects a
  24 va_list * instead of a "...".
  25 
  26 If we want to have more than one probe connected to a marker at a given
  27 time (LTTng, or blktrace, ssytemtap) then we need this patch. Without it,
  28 connecting a second probe handler to a marker will fail.
  29 
  30 It allow us, for instance, to do interesting combinations :
  31 
  32 Do standard tracing with LTTng and, eventually, to compute statistics
  33 with SystemTAP, or to have a special trigger on an event that would call
  34 a systemtap script which would stop flight recorder tracing.
  35 
  36 Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  37 Cc: Christoph Hellwig <hch@infradead.org>
  38 Cc: Mike Mason <mmlnx@us.ibm.com>
  39 Cc: Dipankar Sarma <dipankar@in.ibm.com>
  40 Cc: David Smith <dsmith@redhat.com>
  41 Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
  42 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  43 ---
  44 
  45  include/linux/marker.h          |   59 +-
  46  include/linux/module.h          |    2 
  47  kernel/marker.c                 |  671 ++++++++++++++++++++++--------
  48  kernel/module.c                 |    7 
  49  samples/markers/probe-example.c |   25 -
  50  5 files changed, 548 insertions(+), 216 deletions(-)
  51 
  52 diff -puN include/linux/marker.h~linux-kernel-markers-support-multiple-probes include/linux/marker.h
  53 --- a/include/linux/marker.h~linux-kernel-markers-support-multiple-probes
  54 +++ a/include/linux/marker.h
  55 @@ -19,16 +19,23 @@ struct marker;
  56  
  57  /**
  58   * marker_probe_func - Type of a marker probe function
  59 - * @mdata: pointer of type struct marker
  60 - * @private_data: caller site private data
  61 + * @probe_private: probe private data
  62 + * @call_private: call site private data
  63   * @fmt: format string
  64 - * @...: variable argument list
  65 + * @args: variable argument list pointer. Use a pointer to overcome C's
  66 + *        inability to pass this around as a pointer in a portable manner in
  67 + *        the callee otherwise.
  68   *
  69   * Type of marker probe functions. They receive the mdata and need to parse the
  70   * format string to recover the variable argument list.
  71   */
  72 -typedef void marker_probe_func(const struct marker *mdata,
  73 -	void *private_data, const char *fmt, ...);
  74 +typedef void marker_probe_func(void *probe_private, void *call_private,
  75 +		const char *fmt, va_list *args);
  76 +
  77 +struct marker_probe_closure {
  78 +	marker_probe_func *func;	/* Callback */
  79 +	void *probe_private;		/* Private probe data */
  80 +};
  81  
  82  struct marker {
  83  	const char *name;	/* Marker name */
  84 @@ -36,8 +43,11 @@ struct marker {
  85  				 * variable argument list.
  86  				 */
  87  	char state;		/* Marker state. */
  88 -	marker_probe_func *call;/* Probe handler function pointer */
  89 -	void *private;		/* Private probe data */
  90 +	char ptype;		/* probe type : 0 : single, 1 : multi */
  91 +	void (*call)(const struct marker *mdata,	/* Probe wrapper */
  92 +		void *call_private, const char *fmt, ...);
  93 +	struct marker_probe_closure single;
  94 +	struct marker_probe_closure *multi;
  95  } __attribute__((aligned(8)));
  96  
  97  #ifdef CONFIG_MARKERS
  98 @@ -49,7 +59,7 @@ struct marker {
  99   * not add unwanted padding between the beginning of the section and the
 100   * structure. Force alignment to the same alignment as the section start.
 101   */
 102 -#define __trace_mark(name, call_data, format, args...)			\
 103 +#define __trace_mark(name, call_private, format, args...)		\
 104  	do {								\
 105  		static const char __mstrtab_name_##name[]		\
 106  		__attribute__((section("__markers_strings")))		\
 107 @@ -60,24 +70,23 @@ struct marker {
 108  		static struct marker __mark_##name			\
 109  		__attribute__((section("__markers"), aligned(8))) =	\
 110  		{ __mstrtab_name_##name, __mstrtab_format_##name,	\
 111 -		0, __mark_empty_function, NULL };			\
 112 +		0, 0, marker_probe_cb,					\
 113 +		{ __mark_empty_function, NULL}, NULL };			\
 114  		__mark_check_format(format, ## args);			\
 115  		if (unlikely(__mark_##name.state)) {			\
 116 -			preempt_disable();				\
 117  			(*__mark_##name.call)				\
 118 -				(&__mark_##name, call_data,		\
 119 +				(&__mark_##name, call_private,		\
 120  				format, ## args);			\
 121 -			preempt_enable();				\
 122  		}							\
 123  	} while (0)
 124  
 125  extern void marker_update_probe_range(struct marker *begin,
 126 -	struct marker *end, struct module *probe_module, int *refcount);
 127 +	struct marker *end);
 128  #else /* !CONFIG_MARKERS */
 129 -#define __trace_mark(name, call_data, format, args...) \
 130 +#define __trace_mark(name, call_private, format, args...) \
 131  		__mark_check_format(format, ## args)
 132  static inline void marker_update_probe_range(struct marker *begin,
 133 -	struct marker *end, struct module *probe_module, int *refcount)
 134 +	struct marker *end)
 135  { }
 136  #endif /* CONFIG_MARKERS */
 137  
 138 @@ -92,8 +101,6 @@ static inline void marker_update_probe_r
 139  #define trace_mark(name, format, args...) \
 140  	__trace_mark(name, NULL, format, ## args)
 141  
 142 -#define MARK_MAX_FORMAT_LEN	1024
 143 -
 144  /**
 145   * MARK_NOARGS - Format string for a marker with no argument.
 146   */
 147 @@ -106,24 +113,30 @@ static inline void __printf(1, 2) __mark
 148  
 149  extern marker_probe_func __mark_empty_function;
 150  
 151 +extern void marker_probe_cb(const struct marker *mdata,
 152 +	void *call_private, const char *fmt, ...);
 153 +extern void marker_probe_cb_noarg(const struct marker *mdata,
 154 +	void *call_private, const char *fmt, ...);
 155 +
 156  /*
 157   * Connect a probe to a marker.
 158   * private data pointer must be a valid allocated memory address, or NULL.
 159   */
 160  extern int marker_probe_register(const char *name, const char *format,
 161 -				marker_probe_func *probe, void *private);
 162 +				marker_probe_func *probe, void *probe_private);
 163  
 164  /*
 165   * Returns the private data given to marker_probe_register.
 166   */
 167 -extern void *marker_probe_unregister(const char *name);
 168 +extern int marker_probe_unregister(const char *name,
 169 +	marker_probe_func *probe, void *probe_private);
 170  /*
 171   * Unregister a marker by providing the registered private data.
 172   */
 173 -extern void *marker_probe_unregister_private_data(void *private);
 174 +extern int marker_probe_unregister_private_data(marker_probe_func *probe,
 175 +	void *probe_private);
 176  
 177 -extern int marker_arm(const char *name);
 178 -extern int marker_disarm(const char *name);
 179 -extern void *marker_get_private_data(const char *name);
 180 +extern void *marker_get_private_data(const char *name, marker_probe_func *probe,
 181 +	int num);
 182  
 183  #endif
 184 diff -puN include/linux/module.h~linux-kernel-markers-support-multiple-probes include/linux/module.h
 185 --- a/include/linux/module.h~linux-kernel-markers-support-multiple-probes
 186 +++ a/include/linux/module.h
 187 @@ -462,7 +462,7 @@ int unregister_module_notifier(struct no
 188  
 189  extern void print_modules(void);
 190  
 191 -extern void module_update_markers(struct module *probe_module, int *refcount);
 192 +extern void module_update_markers(void);
 193  
 194  #else /* !CONFIG_MODULES... */
 195  #define EXPORT_SYMBOL(sym)
 196 diff -puN kernel/marker.c~linux-kernel-markers-support-multiple-probes kernel/marker.c
 197 --- a/kernel/marker.c~linux-kernel-markers-support-multiple-probes
 198 +++ a/kernel/marker.c
 199 @@ -27,35 +27,41 @@
 200  extern struct marker __start___markers[];
 201  extern struct marker __stop___markers[];
 202  
 203 +/* Set to 1 to enable marker debug output */
 204 +const int marker_debug;
 205 +
 206  /*
 207   * markers_mutex nests inside module_mutex. Markers mutex protects the builtin
 208 - * and module markers, the hash table and deferred_sync.
 209 + * and module markers and the hash table.
 210   */
 211  static DEFINE_MUTEX(markers_mutex);
 212  
 213  /*
 214 - * Marker deferred synchronization.
 215 - * Upon marker probe_unregister, we delay call to synchronize_sched() to
 216 - * accelerate mass unregistration (only when there is no more reference to a
 217 - * given module do we call synchronize_sched()). However, we need to make sure
 218 - * every critical region has ended before we re-arm a marker that has been
 219 - * unregistered and then registered back with a different probe data.
 220 - */
 221 -static int deferred_sync;
 222 -
 223 -/*
 224   * Marker hash table, containing the active markers.
 225   * Protected by module_mutex.
 226   */
 227  #define MARKER_HASH_BITS 6
 228  #define MARKER_TABLE_SIZE (1 << MARKER_HASH_BITS)
 229  
 230 +/*
 231 + * Note about RCU :
 232 + * It is used to make sure every handler has finished using its private data
 233 + * between two consecutive operation (add or remove) on a given marker.  It is
 234 + * also used to delay the free of multiple probes array until a quiescent state
 235 + * is reached.
 236 + */
 237  struct marker_entry {
 238  	struct hlist_node hlist;
 239  	char *format;
 240 -	marker_probe_func *probe;
 241 -	void *private;
 242 +	void (*call)(const struct marker *mdata,	/* Probe wrapper */
 243 +		void *call_private, const char *fmt, ...);
 244 +	struct marker_probe_closure single;
 245 +	struct marker_probe_closure *multi;
 246  	int refcount;	/* Number of times armed. 0 if disarmed. */
 247 +	struct rcu_head rcu;
 248 +	void *oldptr;
 249 +	char rcu_pending:1;
 250 +	char ptype:1;
 251  	char name[0];	/* Contains name'\0'format'\0' */
 252  };
 253  
 254 @@ -63,7 +69,8 @@ static struct hlist_head marker_table[MA
 255  
 256  /**
 257   * __mark_empty_function - Empty probe callback
 258 - * @mdata: pointer of type const struct marker
 259 + * @probe_private: probe private data
 260 + * @call_private: call site private data
 261   * @fmt: format string
 262   * @...: variable argument list
 263   *
 264 @@ -72,13 +79,262 @@ static struct hlist_head marker_table[MA
 265   * though the function pointer change and the marker enabling are two distinct
 266   * operations that modifies the execution flow of preemptible code.
 267   */
 268 -void __mark_empty_function(const struct marker *mdata, void *private,
 269 -	const char *fmt, ...)
 270 +void __mark_empty_function(void *probe_private, void *call_private,
 271 +	const char *fmt, va_list *args)
 272  {
 273  }
 274  EXPORT_SYMBOL_GPL(__mark_empty_function);
 275  
 276  /*
 277 + * marker_probe_cb Callback that prepares the variable argument list for probes.
 278 + * @mdata: pointer of type struct marker
 279 + * @call_private: caller site private data
 280 + * @fmt: format string
 281 + * @...:  Variable argument list.
 282 + *
 283 + * Since we do not use "typical" pointer based RCU in the 1 argument case, we
 284 + * need to put a full smp_rmb() in this branch. This is why we do not use
 285 + * rcu_dereference() for the pointer read.
 286 + */
 287 +void marker_probe_cb(const struct marker *mdata, void *call_private,
 288 +	const char *fmt, ...)
 289 +{
 290 +	va_list args;
 291 +	char ptype;
 292 +
 293 +	preempt_disable();
 294 +	ptype = ACCESS_ONCE(mdata->ptype);
 295 +	if (likely(!ptype)) {
 296 +		marker_probe_func *func;
 297 +		/* Must read the ptype before ptr. They are not data dependant,
 298 +		 * so we put an explicit smp_rmb() here. */
 299 +		smp_rmb();
 300 +		func = ACCESS_ONCE(mdata->single.func);
 301 +		/* Must read the ptr before private data. They are not data
 302 +		 * dependant, so we put an explicit smp_rmb() here. */
 303 +		smp_rmb();
 304 +		va_start(args, fmt);
 305 +		func(mdata->single.probe_private, call_private, fmt, &args);
 306 +		va_end(args);
 307 +	} else {
 308 +		struct marker_probe_closure *multi;
 309 +		int i;
 310 +		/*
 311 +		 * multi points to an array, therefore accessing the array
 312 +		 * depends on reading multi. However, even in this case,
 313 +		 * we must insure that the pointer is read _before_ the array
 314 +		 * data. Same as rcu_dereference, but we need a full smp_rmb()
 315 +		 * in the fast path, so put the explicit barrier here.
 316 +		 */
 317 +		smp_read_barrier_depends();
 318 +		multi = ACCESS_ONCE(mdata->multi);
 319 +		for (i = 0; multi[i].func; i++) {
 320 +			va_start(args, fmt);
 321 +			multi[i].func(multi[i].probe_private, call_private, fmt,
 322 +				&args);
 323 +			va_end(args);
 324 +		}
 325 +	}
 326 +	preempt_enable();
 327 +}
 328 +EXPORT_SYMBOL_GPL(marker_probe_cb);
 329 +
 330 +/*
 331 + * marker_probe_cb Callback that does not prepare the variable argument list.
 332 + * @mdata: pointer of type struct marker
 333 + * @call_private: caller site private data
 334 + * @fmt: format string
 335 + * @...:  Variable argument list.
 336 + *
 337 + * Should be connected to markers "MARK_NOARGS".
 338 + */
 339 +void marker_probe_cb_noarg(const struct marker *mdata,
 340 +	void *call_private, const char *fmt, ...)
 341 +{
 342 +	va_list args;	/* not initialized */
 343 +	char ptype;
 344 +
 345 +	preempt_disable();
 346 +	ptype = ACCESS_ONCE(mdata->ptype);
 347 +	if (likely(!ptype)) {
 348 +		marker_probe_func *func;
 349 +		/* Must read the ptype before ptr. They are not data dependant,
 350 +		 * so we put an explicit smp_rmb() here. */
 351 +		smp_rmb();
 352 +		func = ACCESS_ONCE(mdata->single.func);
 353 +		/* Must read the ptr before private data. They are not data
 354 +		 * dependant, so we put an explicit smp_rmb() here. */
 355 +		smp_rmb();
 356 +		func(mdata->single.probe_private, call_private, fmt, &args);
 357 +	} else {
 358 +		struct marker_probe_closure *multi;
 359 +		int i;
 360 +		/*
 361 +		 * multi points to an array, therefore accessing the array
 362 +		 * depends on reading multi. However, even in this case,
 363 +		 * we must insure that the pointer is read _before_ the array
 364 +		 * data. Same as rcu_dereference, but we need a full smp_rmb()
 365 +		 * in the fast path, so put the explicit barrier here.
 366 +		 */
 367 +		smp_read_barrier_depends();
 368 +		multi = ACCESS_ONCE(mdata->multi);
 369 +		for (i = 0; multi[i].func; i++)
 370 +			multi[i].func(multi[i].probe_private, call_private, fmt,
 371 +				&args);
 372 +	}
 373 +	preempt_enable();
 374 +}
 375 +EXPORT_SYMBOL_GPL(marker_probe_cb_noarg);
 376 +
 377 +static void free_old_closure(struct rcu_head *head)
 378 +{
 379 +	struct marker_entry *entry = container_of(head,
 380 +		struct marker_entry, rcu);
 381 +	kfree(entry->oldptr);
 382 +	/* Make sure we free the data before setting the pending flag to 0 */
 383 +	smp_wmb();
 384 +	entry->rcu_pending = 0;
 385 +}
 386 +
 387 +static inline void debug_print_probes(struct marker_entry *entry)
 388 +{
 389 +	int i;
 390 +
 391 +	if (!marker_debug)
 392 +		return;
 393 +
 394 +	if (!entry->ptype) {
 395 +		printk(KERN_DEBUG "Single probe : %p %p\n",
 396 +			entry->single.func,
 397 +			entry->single.probe_private);
 398 +	} else {
 399 +		for (i = 0; entry->multi[i].func; i++)
 400 +			printk(KERN_DEBUG "Multi probe %d : %p %p\n", i,
 401 +				entry->multi[i].func,
 402 +				entry->multi[i].probe_private);
 403 +	}
 404 +}
 405 +
 406 +static struct marker_probe_closure *
 407 +marker_entry_add_probe(struct marker_entry *entry,
 408 +		marker_probe_func *probe, void *probe_private)
 409 +{
 410 +	int nr_probes = 0;
 411 +	struct marker_probe_closure *old, *new;
 412 +
 413 +	WARN_ON(!probe);
 414 +
 415 +	debug_print_probes(entry);
 416 +	old = entry->multi;
 417 +	if (!entry->ptype) {
 418 +		if (entry->single.func == probe &&
 419 +				entry->single.probe_private == probe_private)
 420 +			return ERR_PTR(-EBUSY);
 421 +		if (entry->single.func == __mark_empty_function) {
 422 +			/* 0 -> 1 probes */
 423 +			entry->single.func = probe;
 424 +			entry->single.probe_private = probe_private;
 425 +			entry->refcount = 1;
 426 +			entry->ptype = 0;
 427 +			debug_print_probes(entry);
 428 +			return NULL;
 429 +		} else {
 430 +			/* 1 -> 2 probes */
 431 +			nr_probes = 1;
 432 +			old = NULL;
 433 +		}
 434 +	} else {
 435 +		/* (N -> N+1), (N != 0, 1) probes */
 436 +		for (nr_probes = 0; old[nr_probes].func; nr_probes++)
 437 +			if (old[nr_probes].func == probe
 438 +					&& old[nr_probes].probe_private
 439 +						== probe_private)
 440 +				return ERR_PTR(-EBUSY);
 441 +	}
 442 +	/* + 2 : one for new probe, one for NULL func */
 443 +	new = kzalloc((nr_probes + 2) * sizeof(struct marker_probe_closure),
 444 +			GFP_KERNEL);
 445 +	if (new == NULL)
 446 +		return ERR_PTR(-ENOMEM);
 447 +	if (!old)
 448 +		new[0] = entry->single;
 449 +	else
 450 +		memcpy(new, old,
 451 +			nr_probes * sizeof(struct marker_probe_closure));
 452 +	new[nr_probes].func = probe;
 453 +	new[nr_probes].probe_private = probe_private;
 454 +	entry->refcount = nr_probes + 1;
 455 +	entry->multi = new;
 456 +	entry->ptype = 1;
 457 +	debug_print_probes(entry);
 458 +	return old;
 459 +}
 460 +
 461 +static struct marker_probe_closure *
 462 +marker_entry_remove_probe(struct marker_entry *entry,
 463 +		marker_probe_func *probe, void *probe_private)
 464 +{
 465 +	int nr_probes = 0, nr_del = 0, i;
 466 +	struct marker_probe_closure *old, *new;
 467 +
 468 +	old = entry->multi;
 469 +
 470 +	debug_print_probes(entry);
 471 +	if (!entry->ptype) {
 472 +		/* 0 -> N is an error */
 473 +		WARN_ON(entry->single.func == __mark_empty_function);
 474 +		/* 1 -> 0 probes */
 475 +		WARN_ON(probe && entry->single.func != probe);
 476 +		WARN_ON(entry->single.probe_private != probe_private);
 477 +		entry->single.func = __mark_empty_function;
 478 +		entry->refcount = 0;
 479 +		entry->ptype = 0;
 480 +		debug_print_probes(entry);
 481 +		return NULL;
 482 +	} else {
 483 +		/* (N -> M), (N > 1, M >= 0) probes */
 484 +		for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
 485 +			if ((!probe || old[nr_probes].func == probe)
 486 +					&& old[nr_probes].probe_private
 487 +						== probe_private)
 488 +				nr_del++;
 489 +		}
 490 +	}
 491 +
 492 +	if (nr_probes - nr_del == 0) {
 493 +		/* N -> 0, (N > 1) */
 494 +		entry->single.func = __mark_empty_function;
 495 +		entry->refcount = 0;
 496 +		entry->ptype = 0;
 497 +	} else if (nr_probes - nr_del == 1) {
 498 +		/* N -> 1, (N > 1) */
 499 +		for (i = 0; old[i].func; i++)
 500 +			if ((probe && old[i].func != probe) ||
 501 +					old[i].probe_private != probe_private)
 502 +				entry->single = old[i];
 503 +		entry->refcount = 1;
 504 +		entry->ptype = 0;
 505 +	} else {
 506 +		int j = 0;
 507 +		/* N -> M, (N > 1, M > 1) */
 508 +		/* + 1 for NULL */
 509 +		new = kzalloc((nr_probes - nr_del + 1)
 510 +			* sizeof(struct marker_probe_closure), GFP_KERNEL);
 511 +		if (new == NULL)
 512 +			return ERR_PTR(-ENOMEM);
 513 +		for (i = 0; old[i].func; i++)
 514 +			if ((probe && old[i].func != probe) ||
 515 +					old[i].probe_private != probe_private)
 516 +				new[j++] = old[i];
 517 +		entry->refcount = nr_probes - nr_del;
 518 +		entry->ptype = 1;
 519 +		entry->multi = new;
 520 +	}
 521 +	debug_print_probes(entry);
 522 +	return old;
 523 +}
 524 +
 525 +/*
 526   * Get marker if the marker is present in the marker hash table.
 527   * Must be called with markers_mutex held.
 528   * Returns NULL if not present.
 529 @@ -102,8 +358,7 @@ static struct marker_entry *get_marker(c
 530   * Add the marker to the marker hash table. Must be called with markers_mutex
 531   * held.
 532   */
 533 -static int add_marker(const char *name, const char *format,
 534 -	marker_probe_func *probe, void *private)
 535 +static struct marker_entry *add_marker(const char *name, const char *format)
 536  {
 537  	struct hlist_head *head;
 538  	struct hlist_node *node;
 539 @@ -118,9 +373,8 @@ static int add_marker(const char *name, 
 540  	hlist_for_each_entry(e, node, head, hlist) {
 541  		if (!strcmp(name, e->name)) {
 542  			printk(KERN_NOTICE
 543 -				"Marker %s busy, probe %p already installed\n",
 544 -				name, e->probe);
 545 -			return -EBUSY;	/* Already there */
 546 +				"Marker %s busy\n", name);
 547 +			return ERR_PTR(-EBUSY);	/* Already there */
 548  		}
 549  	}
 550  	/*
 551 @@ -130,34 +384,42 @@ static int add_marker(const char *name, 
 552  	e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
 553  			GFP_KERNEL);
 554  	if (!e)
 555 -		return -ENOMEM;
 556 +		return ERR_PTR(-ENOMEM);
 557  	memcpy(&e->name[0], name, name_len);
 558  	if (format) {
 559  		e->format = &e->name[name_len];
 560  		memcpy(e->format, format, format_len);
 561 +		if (strcmp(e->format, MARK_NOARGS) == 0)
 562 +			e->call = marker_probe_cb_noarg;
 563 +		else
 564 +			e->call = marker_probe_cb;
 565  		trace_mark(core_marker_format, "name %s format %s",
 566  				e->name, e->format);
 567 -	} else
 568 +	} else {
 569  		e->format = NULL;
 570 -	e->probe = probe;
 571 -	e->private = private;
 572 +		e->call = marker_probe_cb;
 573 +	}
 574 +	e->single.func = __mark_empty_function;
 575 +	e->single.probe_private = NULL;
 576 +	e->multi = NULL;
 577 +	e->ptype = 0;
 578  	e->refcount = 0;
 579 +	e->rcu_pending = 0;
 580  	hlist_add_head(&e->hlist, head);
 581 -	return 0;
 582 +	return e;
 583  }
 584  
 585  /*
 586   * Remove the marker from the marker hash table. Must be called with mutex_lock
 587   * held.
 588   */
 589 -static void *remove_marker(const char *name)
 590 +static int remove_marker(const char *name)
 591  {
 592  	struct hlist_head *head;
 593  	struct hlist_node *node;
 594  	struct marker_entry *e;
 595  	int found = 0;
 596  	size_t len = strlen(name) + 1;
 597 -	void *private = NULL;
 598  	u32 hash = jhash(name, len-1, 0);
 599  
 600  	head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
 601 @@ -167,12 +429,16 @@ static void *remove_marker(const char *n
 602  			break;
 603  		}
 604  	}
 605 -	if (found) {
 606 -		private = e->private;
 607 -		hlist_del(&e->hlist);
 608 -		kfree(e);
 609 -	}
 610 -	return private;
 611 +	if (!found)
 612 +		return -ENOENT;
 613 +	if (e->single.func != __mark_empty_function)
 614 +		return -EBUSY;
 615 +	hlist_del(&e->hlist);
 616 +	/* Make sure the call_rcu has been executed */
 617 +	if (e->rcu_pending)
 618 +		rcu_barrier();
 619 +	kfree(e);
 620 +	return 0;
 621  }
 622  
 623  /*
 624 @@ -184,6 +450,7 @@ static int marker_set_format(struct mark
 625  	size_t name_len = strlen((*entry)->name) + 1;
 626  	size_t format_len = strlen(format) + 1;
 627  
 628 +
 629  	e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
 630  			GFP_KERNEL);
 631  	if (!e)
 632 @@ -191,11 +458,20 @@ static int marker_set_format(struct mark
 633  	memcpy(&e->name[0], (*entry)->name, name_len);
 634  	e->format = &e->name[name_len];
 635  	memcpy(e->format, format, format_len);
 636 -	e->probe = (*entry)->probe;
 637 -	e->private = (*entry)->private;
 638 +	if (strcmp(e->format, MARK_NOARGS) == 0)
 639 +		e->call = marker_probe_cb_noarg;
 640 +	else
 641 +		e->call = marker_probe_cb;
 642 +	e->single = (*entry)->single;
 643 +	e->multi = (*entry)->multi;
 644 +	e->ptype = (*entry)->ptype;
 645  	e->refcount = (*entry)->refcount;
 646 +	e->rcu_pending = 0;
 647  	hlist_add_before(&e->hlist, &(*entry)->hlist);
 648  	hlist_del(&(*entry)->hlist);
 649 +	/* Make sure the call_rcu has been executed */
 650 +	if ((*entry)->rcu_pending)
 651 +		rcu_barrier();
 652  	kfree(*entry);
 653  	*entry = e;
 654  	trace_mark(core_marker_format, "name %s format %s",
 655 @@ -206,7 +482,8 @@ static int marker_set_format(struct mark
 656  /*
 657   * Sets the probe callback corresponding to one marker.
 658   */
 659 -static int set_marker(struct marker_entry **entry, struct marker *elem)
 660 +static int set_marker(struct marker_entry **entry, struct marker *elem,
 661 +		int active)
 662  {
 663  	int ret;
 664  	WARN_ON(strcmp((*entry)->name, elem->name) != 0);
 665 @@ -226,9 +503,43 @@ static int set_marker(struct marker_entr
 666  		if (ret)
 667  			return ret;
 668  	}
 669 -	elem->call = (*entry)->probe;
 670 -	elem->private = (*entry)->private;
 671 -	elem->state = 1;
 672 +
 673 +	/*
 674 +	 * probe_cb setup (statically known) is done here. It is
 675 +	 * asynchronous with the rest of execution, therefore we only
 676 +	 * pass from a "safe" callback (with argument) to an "unsafe"
 677 +	 * callback (does not set arguments).
 678 +	 */
 679 +	elem->call = (*entry)->call;
 680 +	/*
 681 +	 * Sanity check :
 682 +	 * We only update the single probe private data when the ptr is
 683 +	 * set to a _non_ single probe! (0 -> 1 and N -> 1, N != 1)
 684 +	 */
 685 +	WARN_ON(elem->single.func != __mark_empty_function
 686 +		&& elem->single.probe_private
 687 +		!= (*entry)->single.probe_private &&
 688 +		!elem->ptype);
 689 +	elem->single.probe_private = (*entry)->single.probe_private;
 690 +	/*
 691 +	 * Make sure the private data is valid when we update the
 692 +	 * single probe ptr.
 693 +	 */
 694 +	smp_wmb();
 695 +	elem->single.func = (*entry)->single.func;
 696 +	/*
 697 +	 * We also make sure that the new probe callbacks array is consistent
 698 +	 * before setting a pointer to it.
 699 +	 */
 700 +	rcu_assign_pointer(elem->multi, (*entry)->multi);
 701 +	/*
 702 +	 * Update the function or multi probe array pointer before setting the
 703 +	 * ptype.
 704 +	 */
 705 +	smp_wmb();
 706 +	elem->ptype = (*entry)->ptype;
 707 +	elem->state = active;
 708 +
 709  	return 0;
 710  }
 711  
 712 @@ -240,8 +551,12 @@ static int set_marker(struct marker_entr
 713   */
 714  static void disable_marker(struct marker *elem)
 715  {
 716 +	/* leave "call" as is. It is known statically. */
 717  	elem->state = 0;
 718 -	elem->call = __mark_empty_function;
 719 +	elem->single.func = __mark_empty_function;
 720 +	/* Update the function before setting the ptype */
 721 +	smp_wmb();
 722 +	elem->ptype = 0;	/* single probe */
 723  	/*
 724  	 * Leave the private data and id there, because removal is racy and
 725  	 * should be done only after a synchronize_sched(). These are never used
 726 @@ -253,14 +568,11 @@ static void disable_marker(struct marker
 727   * marker_update_probe_range - Update a probe range
 728   * @begin: beginning of the range
 729   * @end: end of the range
 730 - * @probe_module: module address of the probe being updated
 731 - * @refcount: number of references left to the given probe_module (out)
 732   *
 733   * Updates the probe callback corresponding to a range of markers.
 734   */
 735  void marker_update_probe_range(struct marker *begin,
 736 -	struct marker *end, struct module *probe_module,
 737 -	int *refcount)
 738 +	struct marker *end)
 739  {
 740  	struct marker *iter;
 741  	struct marker_entry *mark_entry;
 742 @@ -268,15 +580,12 @@ void marker_update_probe_range(struct ma
 743  	mutex_lock(&markers_mutex);
 744  	for (iter = begin; iter < end; iter++) {
 745  		mark_entry = get_marker(iter->name);
 746 -		if (mark_entry && mark_entry->refcount) {
 747 -			set_marker(&mark_entry, iter);
 748 +		if (mark_entry) {
 749 +			set_marker(&mark_entry, iter,
 750 +					!!mark_entry->refcount);
 751  			/*
 752  			 * ignore error, continue
 753  			 */
 754 -			if (probe_module)
 755 -				if (probe_module ==
 756 -			__module_text_address((unsigned long)mark_entry->probe))
 757 -					(*refcount)++;
 758  		} else {
 759  			disable_marker(iter);
 760  		}
 761 @@ -289,20 +598,27 @@ void marker_update_probe_range(struct ma
 762   * Issues a synchronize_sched() when no reference to the module passed
 763   * as parameter is found in the probes so the probe module can be
 764   * safely unloaded from now on.
 765 + *
 766 + * Internal callback only changed before the first probe is connected to it.
 767 + * Single probe private data can only be changed on 0 -> 1 and 2 -> 1
 768 + * transitions.  All other transitions will leave the old private data valid.
 769 + * This makes the non-atomicity of the callback/private data updates valid.
 770 + *
 771 + * "special case" updates :
 772 + * 0 -> 1 callback
 773 + * 1 -> 0 callback
 774 + * 1 -> 2 callbacks
 775 + * 2 -> 1 callbacks
 776 + * Other updates all behave the same, just like the 2 -> 3 or 3 -> 2 updates.
 777 + * Site effect : marker_set_format may delete the marker entry (creating a
 778 + * replacement).
 779   */
 780 -static void marker_update_probes(struct module *probe_module)
 781 +static void marker_update_probes(void)
 782  {
 783 -	int refcount = 0;
 784 -
 785  	/* Core kernel markers */
 786 -	marker_update_probe_range(__start___markers,
 787 -			__stop___markers, probe_module, &refcount);
 788 +	marker_update_probe_range(__start___markers, __stop___markers);
 789  	/* Markers in modules. */
 790 -	module_update_markers(probe_module, &refcount);
 791 -	if (probe_module && refcount == 0) {
 792 -		synchronize_sched();
 793 -		deferred_sync = 0;
 794 -	}
 795 +	module_update_markers();
 796  }
 797  
 798  /**
 799 @@ -310,33 +626,49 @@ static void marker_update_probes(struct 
 800   * @name: marker name
 801   * @format: format string
 802   * @probe: probe handler
 803 - * @private: probe private data
 804 + * @probe_private: probe private data
 805   *
 806   * private data must be a valid allocated memory address, or NULL.
 807   * Returns 0 if ok, error value on error.
 808 + * The probe address must at least be aligned on the architecture pointer size.
 809   */
 810  int marker_probe_register(const char *name, const char *format,
 811 -			marker_probe_func *probe, void *private)
 812 +			marker_probe_func *probe, void *probe_private)
 813  {
 814  	struct marker_entry *entry;
 815  	int ret = 0;
 816 +	struct marker_probe_closure *old;
 817  
 818  	mutex_lock(&markers_mutex);
 819  	entry = get_marker(name);
 820 -	if (entry && entry->refcount) {
 821 -		ret = -EBUSY;
 822 -		goto end;
 823 -	}
 824 -	if (deferred_sync) {
 825 -		synchronize_sched();
 826 -		deferred_sync = 0;
 827 +	if (!entry) {
 828 +		entry = add_marker(name, format);
 829 +		if (IS_ERR(entry)) {
 830 +			ret = PTR_ERR(entry);
 831 +			goto end;
 832 +		}
 833  	}
 834 -	ret = add_marker(name, format, probe, private);
 835 -	if (ret)
 836 +	/*
 837 +	 * If we detect that a call_rcu is pending for this marker,
 838 +	 * make sure it's executed now.
 839 +	 */
 840 +	if (entry->rcu_pending)
 841 +		rcu_barrier();
 842 +	old = marker_entry_add_probe(entry, probe, probe_private);
 843 +	if (IS_ERR(old)) {
 844 +		ret = PTR_ERR(old);
 845  		goto end;
 846 +	}
 847  	mutex_unlock(&markers_mutex);
 848 -	marker_update_probes(NULL);
 849 -	return ret;
 850 +	marker_update_probes();		/* may update entry */
 851 +	mutex_lock(&markers_mutex);
 852 +	entry = get_marker(name);
 853 +	WARN_ON(!entry);
 854 +	entry->oldptr = old;
 855 +	entry->rcu_pending = 1;
 856 +	/* write rcu_pending before calling the RCU callback */
 857 +	smp_wmb();
 858 +	call_rcu(&entry->rcu, free_old_closure);
 859  end:
 860  	mutex_unlock(&markers_mutex);
 861  	return ret;
 862 @@ -346,171 +678,166 @@ EXPORT_SYMBOL_GPL(marker_probe_register)
 863  /**
 864   * marker_probe_unregister -  Disconnect a probe from a marker
 865   * @name: marker name
 866 + * @probe: probe function pointer
 867 + * @probe_private: probe private data
 868   *
 869   * Returns the private data given to marker_probe_register, or an ERR_PTR().
 870 + * We do not need to call a synchronize_sched to make sure the probes have
 871 + * finished running before doing a module unload, because the module unload
 872 + * itself uses stop_machine(), which insures that every preempt disabled section
 873 + * have finished.
 874   */
 875 -void *marker_probe_unregister(const char *name)
 876 +int marker_probe_unregister(const char *name,
 877 +	marker_probe_func *probe, void *probe_private)
 878  {
 879 -	struct module *probe_module;
 880  	struct marker_entry *entry;
 881 -	void *private;
 882 +	struct marker_probe_closure *old;
 883 +	int ret = 0;
 884  
 885  	mutex_lock(&markers_mutex);
 886  	entry = get_marker(name);
 887  	if (!entry) {
 888 -		private = ERR_PTR(-ENOENT);
 889 +		ret = -ENOENT;
 890  		goto end;
 891  	}
 892 -	entry->refcount = 0;
 893 -	/* In what module is the probe handler ? */
 894 -	probe_module = __module_text_address((unsigned long)entry->probe);
 895 -	private = remove_marker(name);
 896 -	deferred_sync = 1;
 897 +	if (entry->rcu_pending)
 898 +		rcu_barrier();
 899 +	old = marker_entry_remove_probe(entry, probe, probe_private);
 900  	mutex_unlock(&markers_mutex);
 901 -	marker_update_probes(probe_module);
 902 -	return private;
 903 +	marker_update_probes();		/* may update entry */
 904 +	mutex_lock(&markers_mutex);
 905 +	entry = get_marker(name);
 906 +	entry->oldptr = old;
 907 +	entry->rcu_pending = 1;
 908 +	/* write rcu_pending before calling the RCU callback */
 909 +	smp_wmb();
 910 +	call_rcu(&entry->rcu, free_old_closure);
 911 +	remove_marker(name);	/* Ignore busy error message */
 912  end:
 913  	mutex_unlock(&markers_mutex);
 914 -	return private;
 915 +	return ret;
 916  }
 917  EXPORT_SYMBOL_GPL(marker_probe_unregister);
 918  
 919 -/**
 920 - * marker_probe_unregister_private_data -  Disconnect a probe from a marker
 921 - * @private: probe private data
 922 - *
 923 - * Unregister a marker by providing the registered private data.
 924 - * Returns the private data given to marker_probe_register, or an ERR_PTR().
 925 - */
 926 -void *marker_probe_unregister_private_data(void *private)
 927 +static struct marker_entry *
 928 +get_marker_from_private_data(marker_probe_func *probe, void *probe_private)
 929  {
 930 -	struct module *probe_module;
 931 -	struct hlist_head *head;
 932 -	struct hlist_node *node;
 933  	struct marker_entry *entry;
 934 -	int found = 0;
 935  	unsigned int i;
 936 +	struct hlist_head *head;
 937 +	struct hlist_node *node;
 938  
 939 -	mutex_lock(&markers_mutex);
 940  	for (i = 0; i < MARKER_TABLE_SIZE; i++) {
 941  		head = &marker_table[i];
 942  		hlist_for_each_entry(entry, node, head, hlist) {
 943 -			if (entry->private == private) {
 944 -				found = 1;
 945 -				goto iter_end;
 946 +			if (!entry->ptype) {
 947 +				if (entry->single.func == probe
 948 +						&& entry->single.probe_private
 949 +						== probe_private)
 950 +					return entry;
 951 +			} else {
 952 +				struct marker_probe_closure *closure;
 953 +				closure = entry->multi;
 954 +				for (i = 0; closure[i].func; i++) {
 955 +					if (closure[i].func == probe &&
 956 +							closure[i].probe_private
 957 +							== probe_private)
 958 +						return entry;
 959 +				}
 960  			}
 961  		}
 962  	}
 963 -iter_end:
 964 -	if (!found) {
 965 -		private = ERR_PTR(-ENOENT);
 966 -		goto end;
 967 -	}
 968 -	entry->refcount = 0;
 969 -	/* In what module is the probe handler ? */
 970 -	probe_module = __module_text_address((unsigned long)entry->probe);
 971 -	private = remove_marker(entry->name);
 972 -	deferred_sync = 1;
 973 -	mutex_unlock(&markers_mutex);
 974 -	marker_update_probes(probe_module);
 975 -	return private;
 976 -end:
 977 -	mutex_unlock(&markers_mutex);
 978 -	return private;
 979 +	return NULL;
 980  }
 981 -EXPORT_SYMBOL_GPL(marker_probe_unregister_private_data);
 982  
 983  /**
 984 - * marker_arm - Arm a marker
 985 - * @name: marker name
 986 + * marker_probe_unregister_private_data -  Disconnect a probe from a marker
 987 + * @probe: probe function
 988 + * @probe_private: probe private data
 989   *
 990 - * Activate a marker. It keeps a reference count of the number of
 991 - * arming/disarming done.
 992 - * Returns 0 if ok, error value on error.
 993 + * Unregister a probe by providing the registered private data.
 994 + * Only removes the first marker found in hash table.
 995 + * Return 0 on success or error value.
 996 + * We do not need to call a synchronize_sched to make sure the probes have
 997 + * finished running before doing a module unload, because the module unload
 998 + * itself uses stop_machine(), which insures that every preempt disabled section
 999 + * have finished.
1000   */
1001 -int marker_arm(const char *name)
1002 +int marker_probe_unregister_private_data(marker_probe_func *probe,
1003 +		void *probe_private)
1004  {
1005  	struct marker_entry *entry;
1006  	int ret = 0;
1007 +	struct marker_probe_closure *old;
1008  
1009  	mutex_lock(&markers_mutex);
1010 -	entry = get_marker(name);
1011 +	entry = get_marker_from_private_data(probe, probe_private);
1012  	if (!entry) {
1013  		ret = -ENOENT;
1014  		goto end;
1015  	}
1016 -	/*
1017 -	 * Only need to update probes when refcount passes from 0 to 1.
1018 -	 */
1019 -	if (entry->refcount++)
1020 -		goto end;
1021 -end:
1022 +	if (entry->rcu_pending)
1023 +		rcu_barrier();
1024 +	old = marker_entry_remove_probe(entry, NULL, probe_private);
1025  	mutex_unlock(&markers_mutex);
1026 -	marker_update_probes(NULL);
1027 -	return ret;
1028 -}
1029 -EXPORT_SYMBOL_GPL(marker_arm);
1030 -
1031 -/**
1032 - * marker_disarm - Disarm a marker
1033 - * @name: marker name
1034 - *
1035 - * Disarm a marker. It keeps a reference count of the number of arming/disarming
1036 - * done.
1037 - * Returns 0 if ok, error value on error.
1038 - */
1039 -int marker_disarm(const char *name)
1040 -{
1041 -	struct marker_entry *entry;
1042 -	int ret = 0;
1043 -
1044 +	marker_update_probes();		/* may update entry */
1045  	mutex_lock(&markers_mutex);
1046 -	entry = get_marker(name);
1047 -	if (!entry) {
1048 -		ret = -ENOENT;
1049 -		goto end;
1050 -	}
1051 -	/*
1052 -	 * Only permit decrement refcount if higher than 0.
1053 -	 * Do probe update only on 1 -> 0 transition.
1054 -	 */
1055 -	if (entry->refcount) {
1056 -		if (--entry->refcount)
1057 -			goto end;
1058 -	} else {
1059 -		ret = -EPERM;
1060 -		goto end;
1061 -	}
1062 +	entry = get_marker_from_private_data(probe, probe_private);
1063 +	WARN_ON(!entry);
1064 +	entry->oldptr = old;
1065 +	entry->rcu_pending = 1;
1066 +	/* write rcu_pending before calling the RCU callback */
1067 +	smp_wmb();
1068 +	call_rcu(&entry->rcu, free_old_closure);
1069 +	remove_marker(entry->name);	/* Ignore busy error message */
1070  end:
1071  	mutex_unlock(&markers_mutex);
1072 -	marker_update_probes(NULL);
1073  	return ret;
1074  }
1075 -EXPORT_SYMBOL_GPL(marker_disarm);
1076 +EXPORT_SYMBOL_GPL(marker_probe_unregister_private_data);
1077  
1078  /**
1079   * marker_get_private_data - Get a marker's probe private data
1080   * @name: marker name
1081 + * @probe: probe to match
1082 + * @num: get the nth matching probe's private data
1083   *
1084 + * Returns the nth private data pointer (starting from 0) matching, or an
1085 + * ERR_PTR.
1086   * Returns the private data pointer, or an ERR_PTR.
1087   * The private data pointer should _only_ be dereferenced if the caller is the
1088   * owner of the data, or its content could vanish. This is mostly used to
1089   * confirm that a caller is the owner of a registered probe.
1090   */
1091 -void *marker_get_private_data(const char *name)
1092 +void *marker_get_private_data(const char *name, marker_probe_func *probe,
1093 +		int num)
1094  {
1095  	struct hlist_head *head;
1096  	struct hlist_node *node;
1097  	struct marker_entry *e;
1098  	size_t name_len = strlen(name) + 1;
1099  	u32 hash = jhash(name, name_len-1, 0);
1100 -	int found = 0;
1101 +	int i;
1102  
1103  	head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
1104  	hlist_for_each_entry(e, node, head, hlist) {
1105  		if (!strcmp(name, e->name)) {
1106 -			found = 1;
1107 -			return e->private;
1108 +			if (!e->ptype) {
1109 +				if (num == 0 && e->single.func == probe)
1110 +					return e->single.probe_private;
1111 +				else
1112 +					break;
1113 +			} else {
1114 +				struct marker_probe_closure *closure;
1115 +				int match = 0;
1116 +				closure = e->multi;
1117 +				for (i = 0; closure[i].func; i++) {
1118 +					if (closure[i].func != probe)
1119 +						continue;
1120 +					if (match++ == num)
1121 +						return closure[i].probe_private;
1122 +				}
1123 +			}
1124  		}
1125  	}
1126  	return ERR_PTR(-ENOENT);
1127 diff -puN kernel/module.c~linux-kernel-markers-support-multiple-probes kernel/module.c
1128 --- a/kernel/module.c~linux-kernel-markers-support-multiple-probes
1129 +++ a/kernel/module.c
1130 @@ -1995,7 +1995,7 @@ static struct module *load_module(void _
1131  #ifdef CONFIG_MARKERS
1132  	if (!mod->taints)
1133  		marker_update_probe_range(mod->markers,
1134 -			mod->markers + mod->num_markers, NULL, NULL);
1135 +			mod->markers + mod->num_markers);
1136  #endif
1137  	err = module_finalize(hdr, sechdrs, mod);
1138  	if (err < 0)
1139 @@ -2506,7 +2506,7 @@ EXPORT_SYMBOL(struct_module);
1140  #endif
1141  
1142  #ifdef CONFIG_MARKERS
1143 -void module_update_markers(struct module *probe_module, int *refcount)
1144 +void module_update_markers(void)
1145  {
1146  	struct module *mod;
1147  
1148 @@ -2514,8 +2514,7 @@ void module_update_markers(struct module
1149  	list_for_each_entry(mod, &modules, list)
1150  		if (!mod->taints)
1151  			marker_update_probe_range(mod->markers,
1152 -				mod->markers + mod->num_markers,
1153 -				probe_module, refcount);
1154 +				mod->markers + mod->num_markers);
1155  	mutex_unlock(&module_mutex);
1156  }
1157  #endif
1158 diff -puN samples/markers/probe-example.c~linux-kernel-markers-support-multiple-probes samples/markers/probe-example.c
1159 --- a/samples/markers/probe-example.c~linux-kernel-markers-support-multiple-probes
1160 +++ a/samples/markers/probe-example.c
1161 @@ -20,31 +20,27 @@ struct probe_data {
1162  	marker_probe_func *probe_func;
1163  };
1164  
1165 -void probe_subsystem_event(const struct marker *mdata, void *private,
1166 -	const char *format, ...)
1167 +void probe_subsystem_event(void *probe_data, void *call_data,
1168 +	const char *format, va_list *args)
1169  {
1170 -	va_list ap;
1171  	/* Declare args */
1172  	unsigned int value;
1173  	const char *mystr;
1174  
1175  	/* Assign args */
1176 -	va_start(ap, format);
1177 -	value = va_arg(ap, typeof(value));
1178 -	mystr = va_arg(ap, typeof(mystr));
1179 +	value = va_arg(*args, typeof(value));
1180 +	mystr = va_arg(*args, typeof(mystr));
1181  
1182  	/* Call printk */
1183 -	printk(KERN_DEBUG "Value %u, string %s\n", value, mystr);
1184 +	printk(KERN_INFO "Value %u, string %s\n", value, mystr);
1185  
1186  	/* or count, check rights, serialize data in a buffer */
1187 -
1188 -	va_end(ap);
1189  }
1190  
1191  atomic_t eventb_count = ATOMIC_INIT(0);
1192  
1193 -void probe_subsystem_eventb(const struct marker *mdata, void *private,
1194 -	const char *format, ...)
1195 +void probe_subsystem_eventb(void *probe_data, void *call_data,
1196 +	const char *format, va_list *args)
1197  {
1198  	/* Increment counter */
1199  	atomic_inc(&eventb_count);
1200 @@ -72,10 +68,6 @@ static int __init probe_init(void)
1201  		if (result)
1202  			printk(KERN_INFO "Unable to register probe %s\n",
1203  				probe_array[i].name);
1204 -		result = marker_arm(probe_array[i].name);
1205 -		if (result)
1206 -			printk(KERN_INFO "Unable to arm probe %s\n",
1207 -				probe_array[i].name);
1208  	}
1209  	return 0;
1210  }
1211 @@ -85,7 +77,8 @@ static void __exit probe_fini(void)
1212  	int i;
1213  
1214  	for (i = 0; i < ARRAY_SIZE(probe_array); i++)
1215 -		marker_probe_unregister(probe_array[i].name);
1216 +		marker_probe_unregister(probe_array[i].name,
1217 +			probe_array[i].probe_func, &probe_array[i]);
1218  	printk(KERN_INFO "Number of event b : %u\n",
1219  			atomic_read(&eventb_count));
1220  }
1221 _