[deliverable/linux.git] / drivers / oprofile / cpu_buffer.c

/**
 * @file cpu_buffer.c
 *
 * @remark Copyright 2002 OProfile authors
 * @remark Read the file COPYING
 *
 * @author John Levon <levon@movementarian.org>
 * @author Barry Kasindorf <barry.kasindorf@amd.com>
 *
 * Each CPU has a local buffer that stores PC value/event
 * pairs. We also log context switches when we notice them.
 * Eventually each CPU's buffer is processed into the global
 * event buffer by sync_buffer().
 *
 * We use a local buffer for two reasons: an NMI or similar
 * interrupt cannot synchronise, and high sampling rates
 * would lead to catastrophic global synchronisation if
 * a global buffer was used.
 */

#include <linux/sched.h>
#include <linux/oprofile.h>
#include <linux/vmalloc.h>
#include <linux/errno.h>

#include "event_buffer.h"
#include "cpu_buffer.h"
#include "buffer_sync.h"
#include "oprof.h"

DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);

static void wq_sync_buffer(struct work_struct *work);

#define DEFAULT_TIMER_EXPIRE (HZ / 10)
static int work_enabled;

void free_cpu_buffers(void)
{
	int i;

	for_each_possible_cpu(i) {
		vfree(per_cpu(cpu_buffer, i).buffer);
		per_cpu(cpu_buffer, i).buffer = NULL;
	}
}

unsigned long oprofile_get_cpu_buffer_size(void)
{
	return fs_cpu_buffer_size;
}

void oprofile_cpu_buffer_inc_smpl_lost(void)
{
	struct oprofile_cpu_buffer *cpu_buf
		= &__get_cpu_var(cpu_buffer);

	cpu_buf->sample_lost_overflow++;
}

int alloc_cpu_buffers(void)
{
	int i;

	unsigned long buffer_size = fs_cpu_buffer_size;

	for_each_possible_cpu(i) {
		struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);

		b->buffer = vmalloc_node(sizeof(struct op_sample) * buffer_size,
			cpu_to_node(i));
		if (!b->buffer)
			goto fail;

		b->last_task = NULL;
		b->last_is_kernel = -1;
		b->tracing = 0;
		b->buffer_size = buffer_size;
		b->tail_pos = 0;
		b->head_pos = 0;
		b->sample_received = 0;
		b->sample_lost_overflow = 0;
		b->backtrace_aborted = 0;
		b->sample_invalid_eip = 0;
		b->cpu = i;
		INIT_DELAYED_WORK(&b->work, wq_sync_buffer);
	}
	return 0;

fail:
	free_cpu_buffers();
	return -ENOMEM;
}

void start_cpu_work(void)
{
	int i;

	work_enabled = 1;

	for_each_online_cpu(i) {
		struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);

		/*
		 * Spread the work by 1 jiffy per cpu so they dont all
		 * fire at once.
		 */
		schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i);
	}
}

void end_cpu_work(void)
{
	int i;

	work_enabled = 0;

	for_each_online_cpu(i) {
		struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);

		cancel_delayed_work(&b->work);
	}

	flush_scheduled_work();
}

/* Resets the cpu buffer to a sane state. */
void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf)
{
	/* reset these to invalid values; the next sample
	 * collected will populate the buffer with proper
	 * values to initialize the buffer
	 */
	cpu_buf->last_is_kernel = -1;
	cpu_buf->last_task = NULL;
}

/* compute number of available slots in cpu_buffer queue */
static unsigned long nr_available_slots(struct oprofile_cpu_buffer const *b)
{
	unsigned long head = b->head_pos;
	unsigned long tail = b->tail_pos;

	if (tail > head)
		return (tail - head) - 1;

	return tail + (b->buffer_size - head) - 1;
}

static void increment_head(struct oprofile_cpu_buffer *b)
{
	unsigned long new_head = b->head_pos + 1;

	/* Ensure anything written to the slot before we
	 * increment is visible */
	wmb();

	if (new_head < b->buffer_size)
		b->head_pos = new_head;
	else
		b->head_pos = 0;
}

static inline void
add_sample(struct oprofile_cpu_buffer *cpu_buf,
	   unsigned long pc, unsigned long event)
{
	struct op_sample *entry = &cpu_buf->buffer[cpu_buf->head_pos];
	entry->eip = pc;
	entry->event = event;
	increment_head(cpu_buf);
}

static inline void
add_code(struct oprofile_cpu_buffer *buffer, unsigned long value)
{
	add_sample(buffer, ESCAPE_CODE, value);
}

/* This must be safe from any context. It's safe writing here
 * because of the head/tail separation of the writer and reader
 * of the CPU buffer.
 *
 * is_kernel is needed because on some architectures you cannot
 * tell if you are in kernel or user space simply by looking at
 * pc. We tag this in the buffer by generating kernel enter/exit
 * events whenever is_kernel changes
 */
static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
		      int is_kernel, unsigned long event)
{
	struct task_struct *task;

	cpu_buf->sample_received++;

	if (pc == ESCAPE_CODE) {
		cpu_buf->sample_invalid_eip++;
		return 0;
	}

	if (nr_available_slots(cpu_buf) < 3) {
		cpu_buf->sample_lost_overflow++;
		return 0;
	}

	is_kernel = !!is_kernel;

	task = current;

	/* notice a switch from user->kernel or vice versa */
	if (cpu_buf->last_is_kernel != is_kernel) {
		cpu_buf->last_is_kernel = is_kernel;
		add_code(cpu_buf, is_kernel);
	}

	/* notice a task switch */
	if (cpu_buf->last_task != task) {
		cpu_buf->last_task = task;
		add_code(cpu_buf, (unsigned long)task);
	}

	add_sample(cpu_buf, pc, event);
	return 1;
}

static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
{
	if (nr_available_slots(cpu_buf) < 4) {
		cpu_buf->sample_lost_overflow++;
		return 0;
	}

	add_code(cpu_buf, CPU_TRACE_BEGIN);
	cpu_buf->tracing = 1;
	return 1;
}

static void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf)
{
	cpu_buf->tracing = 0;
}

void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
				unsigned long event, int is_kernel)
{
	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);

	if (!backtrace_depth) {
		log_sample(cpu_buf, pc, is_kernel, event);
		return;
	}

	if (!oprofile_begin_trace(cpu_buf))
		return;

	/* if log_sample() fail we can't backtrace since we lost the source
	 * of this event */
	if (log_sample(cpu_buf, pc, is_kernel, event))
		oprofile_ops.backtrace(regs, backtrace_depth);
	oprofile_end_trace(cpu_buf);
}

void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
{
	int is_kernel = !user_mode(regs);
	unsigned long pc = profile_pc(regs);

	oprofile_add_ext_sample(pc, regs, event, is_kernel);
}

#ifdef CONFIG_OPROFILE_IBS

#define MAX_IBS_SAMPLE_SIZE 14

void oprofile_add_ibs_sample(struct pt_regs *const regs,
			     unsigned int *const ibs_sample, int ibs_code)
{
	int is_kernel = !user_mode(regs);
	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
	struct task_struct *task;

	cpu_buf->sample_received++;

	if (nr_available_slots(cpu_buf) < MAX_IBS_SAMPLE_SIZE) {
		/* we can't backtrace since we lost the source of this event */
		cpu_buf->sample_lost_overflow++;
		return;
	}

	/* notice a switch from user->kernel or vice versa */
	if (cpu_buf->last_is_kernel != is_kernel) {
		cpu_buf->last_is_kernel = is_kernel;
		add_code(cpu_buf, is_kernel);
	}

	/* notice a task switch */
	if (!is_kernel) {
		task = current;
		if (cpu_buf->last_task != task) {
			cpu_buf->last_task = task;
			add_code(cpu_buf, (unsigned long)task);
		}
	}

	add_code(cpu_buf, ibs_code);
	add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]);
	add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]);
	add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]);

	if (ibs_code == IBS_OP_BEGIN) {
		add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]);
		add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]);
		add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]);
	}

	if (backtrace_depth)
		oprofile_ops.backtrace(regs, backtrace_depth);
}

#endif

void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
{
	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
	log_sample(cpu_buf, pc, is_kernel, event);
}

void oprofile_add_trace(unsigned long pc)
{
	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);

	if (!cpu_buf->tracing)
		return;

	if (nr_available_slots(cpu_buf) < 1) {
		cpu_buf->tracing = 0;
		cpu_buf->sample_lost_overflow++;
		return;
	}

	/* broken frame can give an eip with the same value as an escape code,
	 * abort the trace if we get it */
	if (pc == ESCAPE_CODE) {
		cpu_buf->tracing = 0;
		cpu_buf->backtrace_aborted++;
		return;
	}

	add_sample(cpu_buf, pc, 0);
}

/*
 * This serves to avoid cpu buffer overflow, and makes sure
 * the task mortuary progresses
 *
 * By using schedule_delayed_work_on and then schedule_delayed_work
 * we guarantee this will stay on the correct cpu
 */
static void wq_sync_buffer(struct work_struct *work)
{
	struct oprofile_cpu_buffer *b =
		container_of(work, struct oprofile_cpu_buffer, work.work);
	if (b->cpu != smp_processor_id()) {
		printk(KERN_DEBUG "WQ on CPU%d, prefer CPU%d\n",
		       smp_processor_id(), b->cpu);

		if (!cpu_online(b->cpu)) {
			cancel_delayed_work(&b->work);
			return;
		}
	}
	sync_buffer(b->cpu);

	/* don't re-add the work if we're shutting down */
	if (work_enabled)
		schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE);
}
Commit	Line	Data
1da177e4 LT	1	/**
	2	* @file cpu_buffer.c
	3	*
	4	* @remark Copyright 2002 OProfile authors
	5	* @remark Read the file COPYING
	6	*
	7	* @author John Levon <levon@movementarian.org>
345c2573	8	* @author Barry Kasindorf <barry.kasindorf@amd.com>
1da177e4 LT	9	*
	10	* Each CPU has a local buffer that stores PC value/event
	11	* pairs. We also log context switches when we notice them.
	12	* Eventually each CPU's buffer is processed into the global
	13	* event buffer by sync_buffer().
	14	*
	15	* We use a local buffer for two reasons: an NMI or similar
	16	* interrupt cannot synchronise, and high sampling rates
	17	* would lead to catastrophic global synchronisation if
	18	* a global buffer was used.
	19	*/
	20
	21	#include <linux/sched.h>
	22	#include <linux/oprofile.h>
	23	#include <linux/vmalloc.h>
	24	#include <linux/errno.h>
6a18037d	25
1da177e4 LT	26	#include "event_buffer.h"
	27	#include "cpu_buffer.h"
	28	#include "buffer_sync.h"
	29	#include "oprof.h"
	30
8b8b4988	31	DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
1da177e4	32
c4028958	33	static void wq_sync_buffer(struct work_struct *work);
1da177e4 LT	34
	35	#define DEFAULT_TIMER_EXPIRE (HZ / 10)
	36	static int work_enabled;
	37
	38	void free_cpu_buffers(void)
	39	{
	40	int i;
a5598ca0	41
4bd9b9dc	42	for_each_possible_cpu(i) {
608dfddd	43	vfree(per_cpu(cpu_buffer, i).buffer);
f4156d1c CL	44	per_cpu(cpu_buffer, i).buffer = NULL;
f4156d1c CL	45	}
1da177e4	46	}
77933d72	47
a5598ca0 CL	48	unsigned long oprofile_get_cpu_buffer_size(void)
	49	{
	50	return fs_cpu_buffer_size;
	51	}
	52
	53	void oprofile_cpu_buffer_inc_smpl_lost(void)
	54	{
	55	struct oprofile_cpu_buffer *cpu_buf
	56	= &__get_cpu_var(cpu_buffer);
	57
	58	cpu_buf->sample_lost_overflow++;
	59	}
	60
1da177e4 LT	61	int alloc_cpu_buffers(void)
	62	{
	63	int i;
6a18037d	64
1da177e4	65	unsigned long buffer_size = fs_cpu_buffer_size;
6a18037d	66
4bd9b9dc	67	for_each_possible_cpu(i) {
608dfddd	68	struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
6a18037d	69
25ab7cd8 ED	70	b->buffer = vmalloc_node(sizeof(struct op_sample) * buffer_size,
25ab7cd8 ED	71	cpu_to_node(i));
1da177e4 LT	72	if (!b->buffer)
1da177e4 LT	73	goto fail;
6a18037d	74
1da177e4 LT	75	b->last_task = NULL;
	76	b->last_is_kernel = -1;
	77	b->tracing = 0;
	78	b->buffer_size = buffer_size;
	79	b->tail_pos = 0;
	80	b->head_pos = 0;
	81	b->sample_received = 0;
	82	b->sample_lost_overflow = 0;
df9d177a PE	83	b->backtrace_aborted = 0;
df9d177a PE	84	b->sample_invalid_eip = 0;
1da177e4	85	b->cpu = i;
c4028958	86	INIT_DELAYED_WORK(&b->work, wq_sync_buffer);
1da177e4 LT	87	}
	88	return 0;
	89
	90	fail:
	91	free_cpu_buffers();
	92	return -ENOMEM;
	93	}
1da177e4 LT	94
	95	void start_cpu_work(void)
	96	{
	97	int i;
	98
	99	work_enabled = 1;
	100
	101	for_each_online_cpu(i) {
608dfddd	102	struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
1da177e4 LT	103
	104	/*
	105	* Spread the work by 1 jiffy per cpu so they dont all
	106	* fire at once.
	107	*/
	108	schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i);
	109	}
	110	}
	111
1da177e4 LT	112	void end_cpu_work(void)
	113	{
	114	int i;
	115
	116	work_enabled = 0;
	117
	118	for_each_online_cpu(i) {
608dfddd	119	struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
1da177e4 LT	120
	121	cancel_delayed_work(&b->work);
	122	}
	123
	124	flush_scheduled_work();
	125	}
	126
1da177e4	127	/* Resets the cpu buffer to a sane state. */
25ad2913	128	void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf)
1da177e4 LT	129	{
	130	/* reset these to invalid values; the next sample
	131	* collected will populate the buffer with proper
	132	* values to initialize the buffer
	133	*/
	134	cpu_buf->last_is_kernel = -1;
	135	cpu_buf->last_task = NULL;
	136	}
	137
1da177e4	138	/* compute number of available slots in cpu_buffer queue */
25ad2913	139	static unsigned long nr_available_slots(struct oprofile_cpu_buffer const *b)
1da177e4 LT	140	{
	141	unsigned long head = b->head_pos;
	142	unsigned long tail = b->tail_pos;
	143
	144	if (tail > head)
	145	return (tail - head) - 1;
	146
	147	return tail + (b->buffer_size - head) - 1;
	148	}
	149
25ad2913	150	static void increment_head(struct oprofile_cpu_buffer *b)
1da177e4 LT	151	{
	152	unsigned long new_head = b->head_pos + 1;
	153
	154	/* Ensure anything written to the slot before we
	155	* increment is visible */
	156	wmb();
	157
	158	if (new_head < b->buffer_size)
	159	b->head_pos = new_head;
	160	else
	161	b->head_pos = 0;
	162	}
	163
77933d72	164	static inline void
25ad2913	165	add_sample(struct oprofile_cpu_buffer *cpu_buf,
6a18037d	166	unsigned long pc, unsigned long event)
1da177e4	167	{
25ad2913	168	struct op_sample *entry = &cpu_buf->buffer[cpu_buf->head_pos];
1da177e4 LT	169	entry->eip = pc;
	170	entry->event = event;
	171	increment_head(cpu_buf);
	172	}
	173
77933d72	174	static inline void
25ad2913	175	add_code(struct oprofile_cpu_buffer *buffer, unsigned long value)
1da177e4 LT	176	{
	177	add_sample(buffer, ESCAPE_CODE, value);
	178	}
	179
1da177e4 LT	180	/* This must be safe from any context. It's safe writing here
	181	* because of the head/tail separation of the writer and reader
	182	* of the CPU buffer.
	183	*
	184	* is_kernel is needed because on some architectures you cannot
	185	* tell if you are in kernel or user space simply by looking at
	186	* pc. We tag this in the buffer by generating kernel enter/exit
	187	* events whenever is_kernel changes
	188	*/
25ad2913	189	static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
1da177e4 LT	190	int is_kernel, unsigned long event)
1da177e4 LT	191	{
25ad2913	192	struct task_struct *task;
1da177e4 LT	193
	194	cpu_buf->sample_received++;
	195
df9d177a PE	196	if (pc == ESCAPE_CODE) {
	197	cpu_buf->sample_invalid_eip++;
	198	return 0;
	199	}
	200
1da177e4 LT	201	if (nr_available_slots(cpu_buf) < 3) {
	202	cpu_buf->sample_lost_overflow++;
	203	return 0;
	204	}
	205
	206	is_kernel = !!is_kernel;
	207
	208	task = current;
	209
	210	/* notice a switch from user->kernel or vice versa */
	211	if (cpu_buf->last_is_kernel != is_kernel) {
	212	cpu_buf->last_is_kernel = is_kernel;
	213	add_code(cpu_buf, is_kernel);
	214	}
	215
	216	/* notice a task switch */
	217	if (cpu_buf->last_task != task) {
	218	cpu_buf->last_task = task;
	219	add_code(cpu_buf, (unsigned long)task);
	220	}
6a18037d	221
1da177e4 LT	222	add_sample(cpu_buf, pc, event);
	223	return 1;
	224	}
	225
345c2573	226	static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
1da177e4 LT	227	{
	228	if (nr_available_slots(cpu_buf) < 4) {
	229	cpu_buf->sample_lost_overflow++;
	230	return 0;
	231	}
	232
	233	add_code(cpu_buf, CPU_TRACE_BEGIN);
	234	cpu_buf->tracing = 1;
	235	return 1;
	236	}
	237
25ad2913	238	static void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf)
1da177e4 LT	239	{
	240	cpu_buf->tracing = 0;
	241	}
	242
27357716 BR	243	void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
27357716 BR	244	unsigned long event, int is_kernel)
1da177e4	245	{
608dfddd	246	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
1da177e4 LT	247
	248	if (!backtrace_depth) {
	249	log_sample(cpu_buf, pc, is_kernel, event);
	250	return;
	251	}
	252
	253	if (!oprofile_begin_trace(cpu_buf))
	254	return;
	255
	256	/* if log_sample() fail we can't backtrace since we lost the source
	257	* of this event */
	258	if (log_sample(cpu_buf, pc, is_kernel, event))
	259	oprofile_ops.backtrace(regs, backtrace_depth);
	260	oprofile_end_trace(cpu_buf);
	261	}
	262
27357716 BR	263	void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
	264	{
	265	int is_kernel = !user_mode(regs);
	266	unsigned long pc = profile_pc(regs);
	267
	268	oprofile_add_ext_sample(pc, regs, event, is_kernel);
	269	}
	270
852402cc RR	271	#ifdef CONFIG_OPROFILE_IBS
852402cc RR	272
e2fee276 RR	273	#define MAX_IBS_SAMPLE_SIZE 14
	274
	275	void oprofile_add_ibs_sample(struct pt_regs *const regs,
25ad2913	276	unsigned int *const ibs_sample, int ibs_code)
345c2573	277	{
e2fee276 RR	278	int is_kernel = !user_mode(regs);
e2fee276 RR	279	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
345c2573 BK	280	struct task_struct *task;
	281
	282	cpu_buf->sample_received++;
	283
	284	if (nr_available_slots(cpu_buf) < MAX_IBS_SAMPLE_SIZE) {
e2fee276	285	/* we can't backtrace since we lost the source of this event */
345c2573	286	cpu_buf->sample_lost_overflow++;
e2fee276	287	return;
345c2573 BK	288	}
345c2573 BK	289
345c2573 BK	290	/* notice a switch from user->kernel or vice versa */
	291	if (cpu_buf->last_is_kernel != is_kernel) {
	292	cpu_buf->last_is_kernel = is_kernel;
	293	add_code(cpu_buf, is_kernel);
	294	}
	295
	296	/* notice a task switch */
	297	if (!is_kernel) {
	298	task = current;
345c2573 BK	299	if (cpu_buf->last_task != task) {
	300	cpu_buf->last_task = task;
	301	add_code(cpu_buf, (unsigned long)task);
	302	}
	303	}
	304
	305	add_code(cpu_buf, ibs_code);
e2fee276 RR	306	add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]);
	307	add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]);
	308	add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]);
345c2573 BK	309
345c2573 BK	310	if (ibs_code == IBS_OP_BEGIN) {
e2fee276 RR	311	add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]);
	312	add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]);
	313	add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]);
345c2573 BK	314	}
345c2573 BK	315
e2fee276	316	if (backtrace_depth)
345c2573 BK	317	oprofile_ops.backtrace(regs, backtrace_depth);
	318	}
	319
852402cc RR	320	#endif
852402cc RR	321
1da177e4 LT	322	void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
1da177e4 LT	323	{
608dfddd	324	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
1da177e4 LT	325	log_sample(cpu_buf, pc, is_kernel, event);
	326	}
	327
1da177e4 LT	328	void oprofile_add_trace(unsigned long pc)
1da177e4 LT	329	{
608dfddd	330	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
1da177e4 LT	331
	332	if (!cpu_buf->tracing)
	333	return;
	334
	335	if (nr_available_slots(cpu_buf) < 1) {
	336	cpu_buf->tracing = 0;
	337	cpu_buf->sample_lost_overflow++;
	338	return;
	339	}
	340
	341	/* broken frame can give an eip with the same value as an escape code,
	342	* abort the trace if we get it */
	343	if (pc == ESCAPE_CODE) {
	344	cpu_buf->tracing = 0;
	345	cpu_buf->backtrace_aborted++;
	346	return;
	347	}
	348
	349	add_sample(cpu_buf, pc, 0);
	350	}
	351
1da177e4 LT	352	/*
	353	* This serves to avoid cpu buffer overflow, and makes sure
	354	* the task mortuary progresses
	355	*
	356	* By using schedule_delayed_work_on and then schedule_delayed_work
	357	* we guarantee this will stay on the correct cpu
	358	*/
c4028958	359	static void wq_sync_buffer(struct work_struct *work)
1da177e4	360	{
25ad2913	361	struct oprofile_cpu_buffer *b =
c4028958	362	container_of(work, struct oprofile_cpu_buffer, work.work);
1da177e4	363	if (b->cpu != smp_processor_id()) {
bd17b625	364	printk(KERN_DEBUG "WQ on CPU%d, prefer CPU%d\n",
1da177e4	365	smp_processor_id(), b->cpu);
4bd9b9dc CA	366
	367	if (!cpu_online(b->cpu)) {
	368	cancel_delayed_work(&b->work);
	369	return;
	370	}
1da177e4 LT	371	}
	372	sync_buffer(b->cpu);
	373
	374	/* don't re-add the work if we're shutting down */
	375	if (work_enabled)
	376	schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE);
	377	}