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1 /*
2  *  linux/kernel/profile.c
3  *  Simple profiling. Manages a direct-mapped profile hit count buffer,
4  *  with configurable resolution, support for restricting the cpus on
5  *  which profiling is done, and switching between cpu time and
6  *  schedule() calls via kernel command line parameters passed at boot.
7  *
8  *  Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
9  *	Red Hat, July 2004
10  *  Consolidation of architecture support code for profiling,
11  *	Nadia Yvette Chambers, Oracle, July 2004
12  *  Amortized hit count accounting via per-cpu open-addressed hashtables
13  *	to resolve timer interrupt livelocks, Nadia Yvette Chambers,
14  *	Oracle, 2004
15  */
16 
17 #include <linux/export.h>
18 #include <linux/profile.h>
19 #include <linux/bootmem.h>
20 #include <linux/notifier.h>
21 #include <linux/mm.h>
22 #include <linux/cpumask.h>
23 #include <linux/cpu.h>
24 #include <linux/highmem.h>
25 #include <linux/mutex.h>
26 #include <linux/slab.h>
27 #include <linux/vmalloc.h>
28 #include <asm/sections.h>
29 #include <asm/irq_regs.h>
30 #include <asm/ptrace.h>
31 
32 struct profile_hit {
33 	u32 pc, hits;
34 };
35 #define PROFILE_GRPSHIFT	3
36 #define PROFILE_GRPSZ		(1 << PROFILE_GRPSHIFT)
37 #define NR_PROFILE_HIT		(PAGE_SIZE/sizeof(struct profile_hit))
38 #define NR_PROFILE_GRP		(NR_PROFILE_HIT/PROFILE_GRPSZ)
39 
40 static atomic_t *prof_buffer;
41 static unsigned long prof_len;
42 static unsigned short int prof_shift;
43 
44 int prof_on __read_mostly;
45 EXPORT_SYMBOL_GPL(prof_on);
46 
47 static cpumask_var_t prof_cpu_mask;
48 #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
49 static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
50 static DEFINE_PER_CPU(int, cpu_profile_flip);
51 static DEFINE_MUTEX(profile_flip_mutex);
52 #endif /* CONFIG_SMP */
53 
profile_setup(char * str)54 int profile_setup(char *str)
55 {
56 	static const char schedstr[] = "schedule";
57 	static const char sleepstr[] = "sleep";
58 	static const char kvmstr[] = "kvm";
59 	int par;
60 
61 	if (!strncmp(str, sleepstr, strlen(sleepstr))) {
62 #ifdef CONFIG_SCHEDSTATS
63 		prof_on = SLEEP_PROFILING;
64 		if (str[strlen(sleepstr)] == ',')
65 			str += strlen(sleepstr) + 1;
66 		if (get_option(&str, &par))
67 			prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
68 		pr_info("kernel sleep profiling enabled (shift: %u)\n",
69 			prof_shift);
70 #else
71 		pr_warn("kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
72 #endif /* CONFIG_SCHEDSTATS */
73 	} else if (!strncmp(str, schedstr, strlen(schedstr))) {
74 		prof_on = SCHED_PROFILING;
75 		if (str[strlen(schedstr)] == ',')
76 			str += strlen(schedstr) + 1;
77 		if (get_option(&str, &par))
78 			prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
79 		pr_info("kernel schedule profiling enabled (shift: %u)\n",
80 			prof_shift);
81 	} else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
82 		prof_on = KVM_PROFILING;
83 		if (str[strlen(kvmstr)] == ',')
84 			str += strlen(kvmstr) + 1;
85 		if (get_option(&str, &par))
86 			prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
87 		pr_info("kernel KVM profiling enabled (shift: %u)\n",
88 			prof_shift);
89 	} else if (get_option(&str, &par)) {
90 		prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
91 		prof_on = CPU_PROFILING;
92 		pr_info("kernel profiling enabled (shift: %u)\n",
93 			prof_shift);
94 	}
95 	return 1;
96 }
97 __setup("profile=", profile_setup);
98 
99 
profile_init(void)100 int __ref profile_init(void)
101 {
102 	int buffer_bytes;
103 	if (!prof_on)
104 		return 0;
105 
106 	/* only text is profiled */
107 	prof_len = (_etext - _stext) >> prof_shift;
108 	buffer_bytes = prof_len*sizeof(atomic_t);
109 
110 	if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
111 		return -ENOMEM;
112 
113 	cpumask_copy(prof_cpu_mask, cpu_possible_mask);
114 
115 	prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
116 	if (prof_buffer)
117 		return 0;
118 
119 	prof_buffer = alloc_pages_exact(buffer_bytes,
120 					GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
121 	if (prof_buffer)
122 		return 0;
123 
124 	prof_buffer = vzalloc(buffer_bytes);
125 	if (prof_buffer)
126 		return 0;
127 
128 	free_cpumask_var(prof_cpu_mask);
129 	return -ENOMEM;
130 }
131 
132 /* Profile event notifications */
133 
134 static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
135 static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
136 static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
137 
profile_task_exit(struct task_struct * task)138 void profile_task_exit(struct task_struct *task)
139 {
140 	blocking_notifier_call_chain(&task_exit_notifier, 0, task);
141 }
142 
profile_handoff_task(struct task_struct * task)143 int profile_handoff_task(struct task_struct *task)
144 {
145 	int ret;
146 	ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
147 	return (ret == NOTIFY_OK) ? 1 : 0;
148 }
149 
profile_munmap(unsigned long addr)150 void profile_munmap(unsigned long addr)
151 {
152 	blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
153 }
154 
task_handoff_register(struct notifier_block * n)155 int task_handoff_register(struct notifier_block *n)
156 {
157 	return atomic_notifier_chain_register(&task_free_notifier, n);
158 }
159 EXPORT_SYMBOL_GPL(task_handoff_register);
160 
task_handoff_unregister(struct notifier_block * n)161 int task_handoff_unregister(struct notifier_block *n)
162 {
163 	return atomic_notifier_chain_unregister(&task_free_notifier, n);
164 }
165 EXPORT_SYMBOL_GPL(task_handoff_unregister);
166 
profile_event_register(enum profile_type type,struct notifier_block * n)167 int profile_event_register(enum profile_type type, struct notifier_block *n)
168 {
169 	int err = -EINVAL;
170 
171 	switch (type) {
172 	case PROFILE_TASK_EXIT:
173 		err = blocking_notifier_chain_register(
174 				&task_exit_notifier, n);
175 		break;
176 	case PROFILE_MUNMAP:
177 		err = blocking_notifier_chain_register(
178 				&munmap_notifier, n);
179 		break;
180 	}
181 
182 	return err;
183 }
184 EXPORT_SYMBOL_GPL(profile_event_register);
185 
profile_event_unregister(enum profile_type type,struct notifier_block * n)186 int profile_event_unregister(enum profile_type type, struct notifier_block *n)
187 {
188 	int err = -EINVAL;
189 
190 	switch (type) {
191 	case PROFILE_TASK_EXIT:
192 		err = blocking_notifier_chain_unregister(
193 				&task_exit_notifier, n);
194 		break;
195 	case PROFILE_MUNMAP:
196 		err = blocking_notifier_chain_unregister(
197 				&munmap_notifier, n);
198 		break;
199 	}
200 
201 	return err;
202 }
203 EXPORT_SYMBOL_GPL(profile_event_unregister);
204 
205 #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
206 /*
207  * Each cpu has a pair of open-addressed hashtables for pending
208  * profile hits. read_profile() IPI's all cpus to request them
209  * to flip buffers and flushes their contents to prof_buffer itself.
210  * Flip requests are serialized by the profile_flip_mutex. The sole
211  * use of having a second hashtable is for avoiding cacheline
212  * contention that would otherwise happen during flushes of pending
213  * profile hits required for the accuracy of reported profile hits
214  * and so resurrect the interrupt livelock issue.
215  *
216  * The open-addressed hashtables are indexed by profile buffer slot
217  * and hold the number of pending hits to that profile buffer slot on
218  * a cpu in an entry. When the hashtable overflows, all pending hits
219  * are accounted to their corresponding profile buffer slots with
220  * atomic_add() and the hashtable emptied. As numerous pending hits
221  * may be accounted to a profile buffer slot in a hashtable entry,
222  * this amortizes a number of atomic profile buffer increments likely
223  * to be far larger than the number of entries in the hashtable,
224  * particularly given that the number of distinct profile buffer
225  * positions to which hits are accounted during short intervals (e.g.
226  * several seconds) is usually very small. Exclusion from buffer
227  * flipping is provided by interrupt disablement (note that for
228  * SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
229  * process context).
230  * The hash function is meant to be lightweight as opposed to strong,
231  * and was vaguely inspired by ppc64 firmware-supported inverted
232  * pagetable hash functions, but uses a full hashtable full of finite
233  * collision chains, not just pairs of them.
234  *
235  * -- nyc
236  */
__profile_flip_buffers(void * unused)237 static void __profile_flip_buffers(void *unused)
238 {
239 	int cpu = smp_processor_id();
240 
241 	per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
242 }
243 
profile_flip_buffers(void)244 static void profile_flip_buffers(void)
245 {
246 	int i, j, cpu;
247 
248 	mutex_lock(&profile_flip_mutex);
249 	j = per_cpu(cpu_profile_flip, get_cpu());
250 	put_cpu();
251 	on_each_cpu(__profile_flip_buffers, NULL, 1);
252 	for_each_online_cpu(cpu) {
253 		struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
254 		for (i = 0; i < NR_PROFILE_HIT; ++i) {
255 			if (!hits[i].hits) {
256 				if (hits[i].pc)
257 					hits[i].pc = 0;
258 				continue;
259 			}
260 			atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
261 			hits[i].hits = hits[i].pc = 0;
262 		}
263 	}
264 	mutex_unlock(&profile_flip_mutex);
265 }
266 
profile_discard_flip_buffers(void)267 static void profile_discard_flip_buffers(void)
268 {
269 	int i, cpu;
270 
271 	mutex_lock(&profile_flip_mutex);
272 	i = per_cpu(cpu_profile_flip, get_cpu());
273 	put_cpu();
274 	on_each_cpu(__profile_flip_buffers, NULL, 1);
275 	for_each_online_cpu(cpu) {
276 		struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
277 		memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
278 	}
279 	mutex_unlock(&profile_flip_mutex);
280 }
281 
do_profile_hits(int type,void * __pc,unsigned int nr_hits)282 static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
283 {
284 	unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
285 	int i, j, cpu;
286 	struct profile_hit *hits;
287 
288 	pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
289 	i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
290 	secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
291 	cpu = get_cpu();
292 	hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
293 	if (!hits) {
294 		put_cpu();
295 		return;
296 	}
297 	/*
298 	 * We buffer the global profiler buffer into a per-CPU
299 	 * queue and thus reduce the number of global (and possibly
300 	 * NUMA-alien) accesses. The write-queue is self-coalescing:
301 	 */
302 	local_irq_save(flags);
303 	do {
304 		for (j = 0; j < PROFILE_GRPSZ; ++j) {
305 			if (hits[i + j].pc == pc) {
306 				hits[i + j].hits += nr_hits;
307 				goto out;
308 			} else if (!hits[i + j].hits) {
309 				hits[i + j].pc = pc;
310 				hits[i + j].hits = nr_hits;
311 				goto out;
312 			}
313 		}
314 		i = (i + secondary) & (NR_PROFILE_HIT - 1);
315 	} while (i != primary);
316 
317 	/*
318 	 * Add the current hit(s) and flush the write-queue out
319 	 * to the global buffer:
320 	 */
321 	atomic_add(nr_hits, &prof_buffer[pc]);
322 	for (i = 0; i < NR_PROFILE_HIT; ++i) {
323 		atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
324 		hits[i].pc = hits[i].hits = 0;
325 	}
326 out:
327 	local_irq_restore(flags);
328 	put_cpu();
329 }
330 
profile_cpu_callback(struct notifier_block * info,unsigned long action,void * __cpu)331 static int profile_cpu_callback(struct notifier_block *info,
332 					unsigned long action, void *__cpu)
333 {
334 	int node, cpu = (unsigned long)__cpu;
335 	struct page *page;
336 
337 	switch (action) {
338 	case CPU_UP_PREPARE:
339 	case CPU_UP_PREPARE_FROZEN:
340 		node = cpu_to_mem(cpu);
341 		per_cpu(cpu_profile_flip, cpu) = 0;
342 		if (!per_cpu(cpu_profile_hits, cpu)[1]) {
343 			page = __alloc_pages_node(node,
344 					GFP_KERNEL | __GFP_ZERO,
345 					0);
346 			if (!page)
347 				return notifier_from_errno(-ENOMEM);
348 			per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
349 		}
350 		if (!per_cpu(cpu_profile_hits, cpu)[0]) {
351 			page = __alloc_pages_node(node,
352 					GFP_KERNEL | __GFP_ZERO,
353 					0);
354 			if (!page)
355 				goto out_free;
356 			per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
357 		}
358 		break;
359 out_free:
360 		page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
361 		per_cpu(cpu_profile_hits, cpu)[1] = NULL;
362 		__free_page(page);
363 		return notifier_from_errno(-ENOMEM);
364 	case CPU_ONLINE:
365 	case CPU_ONLINE_FROZEN:
366 		if (prof_cpu_mask != NULL)
367 			cpumask_set_cpu(cpu, prof_cpu_mask);
368 		break;
369 	case CPU_UP_CANCELED:
370 	case CPU_UP_CANCELED_FROZEN:
371 	case CPU_DEAD:
372 	case CPU_DEAD_FROZEN:
373 		if (prof_cpu_mask != NULL)
374 			cpumask_clear_cpu(cpu, prof_cpu_mask);
375 		if (per_cpu(cpu_profile_hits, cpu)[0]) {
376 			page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
377 			per_cpu(cpu_profile_hits, cpu)[0] = NULL;
378 			__free_page(page);
379 		}
380 		if (per_cpu(cpu_profile_hits, cpu)[1]) {
381 			page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
382 			per_cpu(cpu_profile_hits, cpu)[1] = NULL;
383 			__free_page(page);
384 		}
385 		break;
386 	}
387 	return NOTIFY_OK;
388 }
389 #else /* !CONFIG_SMP */
390 #define profile_flip_buffers()		do { } while (0)
391 #define profile_discard_flip_buffers()	do { } while (0)
392 #define profile_cpu_callback		NULL
393 
do_profile_hits(int type,void * __pc,unsigned int nr_hits)394 static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
395 {
396 	unsigned long pc;
397 	pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
398 	atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
399 }
400 #endif /* !CONFIG_SMP */
401 
profile_hits(int type,void * __pc,unsigned int nr_hits)402 void profile_hits(int type, void *__pc, unsigned int nr_hits)
403 {
404 	if (prof_on != type || !prof_buffer)
405 		return;
406 	do_profile_hits(type, __pc, nr_hits);
407 }
408 EXPORT_SYMBOL_GPL(profile_hits);
409 
profile_tick(int type)410 void profile_tick(int type)
411 {
412 	struct pt_regs *regs = get_irq_regs();
413 
414 	if (!user_mode(regs) && prof_cpu_mask != NULL &&
415 	    cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
416 		profile_hit(type, (void *)profile_pc(regs));
417 }
418 
419 #ifdef CONFIG_PROC_FS
420 #include <linux/proc_fs.h>
421 #include <linux/seq_file.h>
422 #include <asm/uaccess.h>
423 
prof_cpu_mask_proc_show(struct seq_file * m,void * v)424 static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)
425 {
426 	seq_printf(m, "%*pb\n", cpumask_pr_args(prof_cpu_mask));
427 	return 0;
428 }
429 
prof_cpu_mask_proc_open(struct inode * inode,struct file * file)430 static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
431 {
432 	return single_open(file, prof_cpu_mask_proc_show, NULL);
433 }
434 
prof_cpu_mask_proc_write(struct file * file,const char __user * buffer,size_t count,loff_t * pos)435 static ssize_t prof_cpu_mask_proc_write(struct file *file,
436 	const char __user *buffer, size_t count, loff_t *pos)
437 {
438 	cpumask_var_t new_value;
439 	int err;
440 
441 	if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
442 		return -ENOMEM;
443 
444 	err = cpumask_parse_user(buffer, count, new_value);
445 	if (!err) {
446 		cpumask_copy(prof_cpu_mask, new_value);
447 		err = count;
448 	}
449 	free_cpumask_var(new_value);
450 	return err;
451 }
452 
453 static const struct file_operations prof_cpu_mask_proc_fops = {
454 	.open		= prof_cpu_mask_proc_open,
455 	.read		= seq_read,
456 	.llseek		= seq_lseek,
457 	.release	= single_release,
458 	.write		= prof_cpu_mask_proc_write,
459 };
460 
create_prof_cpu_mask(void)461 void create_prof_cpu_mask(void)
462 {
463 	/* create /proc/irq/prof_cpu_mask */
464 	proc_create("irq/prof_cpu_mask", 0600, NULL, &prof_cpu_mask_proc_fops);
465 }
466 
467 /*
468  * This function accesses profiling information. The returned data is
469  * binary: the sampling step and the actual contents of the profile
470  * buffer. Use of the program readprofile is recommended in order to
471  * get meaningful info out of these data.
472  */
473 static ssize_t
read_profile(struct file * file,char __user * buf,size_t count,loff_t * ppos)474 read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
475 {
476 	unsigned long p = *ppos;
477 	ssize_t read;
478 	char *pnt;
479 	unsigned long sample_step = 1UL << prof_shift;
480 
481 	profile_flip_buffers();
482 	if (p >= (prof_len+1)*sizeof(unsigned int))
483 		return 0;
484 	if (count > (prof_len+1)*sizeof(unsigned int) - p)
485 		count = (prof_len+1)*sizeof(unsigned int) - p;
486 	read = 0;
487 
488 	while (p < sizeof(unsigned int) && count > 0) {
489 		if (put_user(*((char *)(&sample_step)+p), buf))
490 			return -EFAULT;
491 		buf++; p++; count--; read++;
492 	}
493 	pnt = (char *)prof_buffer + p - sizeof(atomic_t);
494 	if (copy_to_user(buf, (void *)pnt, count))
495 		return -EFAULT;
496 	read += count;
497 	*ppos += read;
498 	return read;
499 }
500 
501 /*
502  * Writing to /proc/profile resets the counters
503  *
504  * Writing a 'profiling multiplier' value into it also re-sets the profiling
505  * interrupt frequency, on architectures that support this.
506  */
write_profile(struct file * file,const char __user * buf,size_t count,loff_t * ppos)507 static ssize_t write_profile(struct file *file, const char __user *buf,
508 			     size_t count, loff_t *ppos)
509 {
510 #ifdef CONFIG_SMP
511 	extern int setup_profiling_timer(unsigned int multiplier);
512 
513 	if (count == sizeof(int)) {
514 		unsigned int multiplier;
515 
516 		if (copy_from_user(&multiplier, buf, sizeof(int)))
517 			return -EFAULT;
518 
519 		if (setup_profiling_timer(multiplier))
520 			return -EINVAL;
521 	}
522 #endif
523 	profile_discard_flip_buffers();
524 	memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
525 	return count;
526 }
527 
528 static const struct file_operations proc_profile_operations = {
529 	.read		= read_profile,
530 	.write		= write_profile,
531 	.llseek		= default_llseek,
532 };
533 
534 #ifdef CONFIG_SMP
profile_nop(void * unused)535 static void profile_nop(void *unused)
536 {
537 }
538 
create_hash_tables(void)539 static int create_hash_tables(void)
540 {
541 	int cpu;
542 
543 	for_each_online_cpu(cpu) {
544 		int node = cpu_to_mem(cpu);
545 		struct page *page;
546 
547 		page = __alloc_pages_node(node,
548 				GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
549 				0);
550 		if (!page)
551 			goto out_cleanup;
552 		per_cpu(cpu_profile_hits, cpu)[1]
553 				= (struct profile_hit *)page_address(page);
554 		page = __alloc_pages_node(node,
555 				GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
556 				0);
557 		if (!page)
558 			goto out_cleanup;
559 		per_cpu(cpu_profile_hits, cpu)[0]
560 				= (struct profile_hit *)page_address(page);
561 	}
562 	return 0;
563 out_cleanup:
564 	prof_on = 0;
565 	smp_mb();
566 	on_each_cpu(profile_nop, NULL, 1);
567 	for_each_online_cpu(cpu) {
568 		struct page *page;
569 
570 		if (per_cpu(cpu_profile_hits, cpu)[0]) {
571 			page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
572 			per_cpu(cpu_profile_hits, cpu)[0] = NULL;
573 			__free_page(page);
574 		}
575 		if (per_cpu(cpu_profile_hits, cpu)[1]) {
576 			page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
577 			per_cpu(cpu_profile_hits, cpu)[1] = NULL;
578 			__free_page(page);
579 		}
580 	}
581 	return -1;
582 }
583 #else
584 #define create_hash_tables()			({ 0; })
585 #endif
586 
create_proc_profile(void)587 int __ref create_proc_profile(void) /* false positive from hotcpu_notifier */
588 {
589 	struct proc_dir_entry *entry;
590 	int err = 0;
591 
592 	if (!prof_on)
593 		return 0;
594 
595 	cpu_notifier_register_begin();
596 
597 	if (create_hash_tables()) {
598 		err = -ENOMEM;
599 		goto out;
600 	}
601 
602 	entry = proc_create("profile", S_IWUSR | S_IRUGO,
603 			    NULL, &proc_profile_operations);
604 	if (!entry)
605 		goto out;
606 	proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
607 	__hotcpu_notifier(profile_cpu_callback, 0);
608 
609 out:
610 	cpu_notifier_register_done();
611 	return err;
612 }
613 subsys_initcall(create_proc_profile);
614 #endif /* CONFIG_PROC_FS */
615