[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / events / ring_buffer.c

/*
 * Performance events ring-buffer code:
 *
 *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
 *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
 *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
 *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
 *
 * For licensing details see kernel-base/COPYING
 */

#include <linux/perf_event.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>

#include "internal.h"

static bool perf_output_space(struct ring_buffer *rb, unsigned long tail,
			      unsigned long offset, unsigned long head)
{
	unsigned long sz = perf_data_size(rb);
	unsigned long mask = sz - 1;

	/*
	 * check if user-writable
	 * overwrite : over-write its own tail
	 * !overwrite: buffer possibly drops events.
	 */
	if (rb->overwrite)
		return true;

	/*
	 * verify that payload is not bigger than buffer
	 * otherwise masking logic may fail to detect
	 * the "not enough space" condition
	 */
	if ((head - offset) > sz)
		return false;

	offset = (offset - tail) & mask;
	head   = (head   - tail) & mask;

	if ((int)(head - offset) < 0)
		return false;

	return true;
}

static void perf_output_wakeup(struct perf_output_handle *handle)
{
	atomic_set(&handle->rb->poll, POLL_IN);

	handle->event->pending_wakeup = 1;
	irq_work_queue(&handle->event->pending);
}

/*
 * We need to ensure a later event_id doesn't publish a head when a former
 * event isn't done writing. However since we need to deal with NMIs we
 * cannot fully serialize things.
 *
 * We only publish the head (and generate a wakeup) when the outer-most
 * event completes.
 */
static void perf_output_get_handle(struct perf_output_handle *handle)
{
	struct ring_buffer *rb = handle->rb;

	preempt_disable();
	local_inc(&rb->nest);
	handle->wakeup = local_read(&rb->wakeup);
}

static void perf_output_put_handle(struct perf_output_handle *handle)
{
	struct ring_buffer *rb = handle->rb;
	unsigned long head;

again:
	head = local_read(&rb->head);

	/*
	 * IRQ/NMI can happen here, which means we can miss a head update.
	 */

	if (!local_dec_and_test(&rb->nest))
		goto out;

	/*
	 * Since the mmap() consumer (userspace) can run on a different CPU:
	 *
	 *   kernel				user
	 *
	 *   READ ->data_tail			READ ->data_head
	 *   smp_mb()	(A)			smp_rmb()	(C)
	 *   WRITE $data			READ $data
	 *   smp_wmb()	(B)			smp_mb()	(D)
	 *   STORE ->data_head			WRITE ->data_tail
	 *
	 * Where A pairs with D, and B pairs with C.
	 *
	 * I don't think A needs to be a full barrier because we won't in fact
	 * write data until we see the store from userspace. So we simply don't
	 * issue the data WRITE until we observe it. Be conservative for now.
	 *
	 * OTOH, D needs to be a full barrier since it separates the data READ
	 * from the tail WRITE.
	 *
	 * For B a WMB is sufficient since it separates two WRITEs, and for C
	 * an RMB is sufficient since it separates two READs.
	 *
	 * See perf_output_begin().
	 */
	smp_wmb();
	rb->user_page->data_head = head;

	/*
	 * Now check if we missed an update, rely on the (compiler)
	 * barrier in atomic_dec_and_test() to re-read rb->head.
	 */
	if (unlikely(head != local_read(&rb->head))) {
		local_inc(&rb->nest);
		goto again;
	}

	if (handle->wakeup != local_read(&rb->wakeup))
		perf_output_wakeup(handle);

out:
	preempt_enable();
}

int perf_output_begin(struct perf_output_handle *handle,
		      struct perf_event *event, unsigned int size)
{
	struct ring_buffer *rb;
	unsigned long tail, offset, head;
	int have_lost;
	struct perf_sample_data sample_data;
	struct {
		struct perf_event_header header;
		u64			 id;
		u64			 lost;
	} lost_event;

	rcu_read_lock();
	/*
	 * For inherited events we send all the output towards the parent.
	 */
	if (event->parent)
		event = event->parent;

	rb = rcu_dereference(event->rb);
	if (!rb)
		goto out;

	handle->rb	= rb;
	handle->event	= event;

	if (!rb->nr_pages)
		goto out;

	have_lost = local_read(&rb->lost);
	if (have_lost) {
		lost_event.header.size = sizeof(lost_event);
		perf_event_header__init_id(&lost_event.header, &sample_data,
					   event);
		size += lost_event.header.size;
	}

	perf_output_get_handle(handle);

	do {
		/*
		 * Userspace could choose to issue a mb() before updating the
		 * tail pointer. So that all reads will be completed before the
		 * write is issued.
		 *
		 * See perf_output_put_handle().
		 */
		tail = ACCESS_ONCE(rb->user_page->data_tail);
		smp_mb();
		offset = head = local_read(&rb->head);
		head += size;
		if (unlikely(!perf_output_space(rb, tail, offset, head)))
			goto fail;
	} while (local_cmpxchg(&rb->head, offset, head) != offset);

	if (head - local_read(&rb->wakeup) > rb->watermark)
		local_add(rb->watermark, &rb->wakeup);

	handle->page = offset >> (PAGE_SHIFT + page_order(rb));
	handle->page &= rb->nr_pages - 1;
	handle->size = offset & ((PAGE_SIZE << page_order(rb)) - 1);
	handle->addr = rb->data_pages[handle->page];
	handle->addr += handle->size;
	handle->size = (PAGE_SIZE << page_order(rb)) - handle->size;

	if (have_lost) {
		lost_event.header.type = PERF_RECORD_LOST;
		lost_event.header.misc = 0;
		lost_event.id          = event->id;
		lost_event.lost        = local_xchg(&rb->lost, 0);

		perf_output_put(handle, lost_event);
		perf_event__output_id_sample(event, handle, &sample_data);
	}

	return 0;

fail:
	local_inc(&rb->lost);
	perf_output_put_handle(handle);
out:
	rcu_read_unlock();

	return -ENOSPC;
}

unsigned int perf_output_copy(struct perf_output_handle *handle,
		      const void *buf, unsigned int len)
{
	return __output_copy(handle, buf, len);
}

unsigned int perf_output_skip(struct perf_output_handle *handle,
			      unsigned int len)
{
	return __output_skip(handle, NULL, len);
}

void perf_output_end(struct perf_output_handle *handle)
{
	perf_output_put_handle(handle);
	rcu_read_unlock();
}

static void
ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
{
	long max_size = perf_data_size(rb);

	if (watermark)
		rb->watermark = min(max_size, watermark);

	if (!rb->watermark)
		rb->watermark = max_size / 2;

	if (flags & RING_BUFFER_WRITABLE)
		rb->overwrite = 0;
	else
		rb->overwrite = 1;

	atomic_set(&rb->refcount, 1);

	INIT_LIST_HEAD(&rb->event_list);
	spin_lock_init(&rb->event_lock);
}

#ifndef CONFIG_PERF_USE_VMALLOC

/*
 * Back perf_mmap() with regular GFP_KERNEL-0 pages.
 */

struct page *
perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
{
	if (pgoff > rb->nr_pages)
		return NULL;

	if (pgoff == 0)
		return virt_to_page(rb->user_page);

	return virt_to_page(rb->data_pages[pgoff - 1]);
}

static void *perf_mmap_alloc_page(int cpu)
{
	struct page *page;
	int node;

	node = (cpu == -1) ? cpu : cpu_to_node(cpu);
	page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
	if (!page)
		return NULL;

	return page_address(page);
}

struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
{
	struct ring_buffer *rb;
	unsigned long size;
	int i;

	size = sizeof(struct ring_buffer);
	size += nr_pages * sizeof(void *);

	rb = kzalloc(size, GFP_KERNEL);
	if (!rb)
		goto fail;

	rb->user_page = perf_mmap_alloc_page(cpu);
	if (!rb->user_page)
		goto fail_user_page;

	for (i = 0; i < nr_pages; i++) {
		rb->data_pages[i] = perf_mmap_alloc_page(cpu);
		if (!rb->data_pages[i])
			goto fail_data_pages;
	}

	rb->nr_pages = nr_pages;

	ring_buffer_init(rb, watermark, flags);

	return rb;

fail_data_pages:
	for (i--; i >= 0; i--)
		free_page((unsigned long)rb->data_pages[i]);

	free_page((unsigned long)rb->user_page);

fail_user_page:
	kfree(rb);

fail:
	return NULL;
}

static void perf_mmap_free_page(unsigned long addr)
{
	struct page *page = virt_to_page((void *)addr);

	page->mapping = NULL;
	__free_page(page);
}

void rb_free(struct ring_buffer *rb)
{
	int i;

	perf_mmap_free_page((unsigned long)rb->user_page);
	for (i = 0; i < rb->nr_pages; i++)
		perf_mmap_free_page((unsigned long)rb->data_pages[i]);
	kfree(rb);
}

#else
static int data_page_nr(struct ring_buffer *rb)
{
	return rb->nr_pages << page_order(rb);
}

struct page *
perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
{
	/* The '>' counts in the user page. */
	if (pgoff > data_page_nr(rb))
		return NULL;

	return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE);
}

static void perf_mmap_unmark_page(void *addr)
{
	struct page *page = vmalloc_to_page(addr);

	page->mapping = NULL;
}

static void rb_free_work(struct work_struct *work)
{
	struct ring_buffer *rb;
	void *base;
	int i, nr;

	rb = container_of(work, struct ring_buffer, work);
	nr = data_page_nr(rb);

	base = rb->user_page;
	/* The '<=' counts in the user page. */
	for (i = 0; i <= nr; i++)
		perf_mmap_unmark_page(base + (i * PAGE_SIZE));

	vfree(base);
	kfree(rb);
}

void rb_free(struct ring_buffer *rb)
{
	schedule_work(&rb->work);
}

struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
{
	struct ring_buffer *rb;
	unsigned long size;
	void *all_buf;

	size = sizeof(struct ring_buffer);
	size += sizeof(void *);

	rb = kzalloc(size, GFP_KERNEL);
	if (!rb)
		goto fail;

	INIT_WORK(&rb->work, rb_free_work);

	all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
	if (!all_buf)
		goto fail_all_buf;

	rb->user_page = all_buf;
	rb->data_pages[0] = all_buf + PAGE_SIZE;
	rb->page_order = ilog2(nr_pages);
	rb->nr_pages = !!nr_pages;

	ring_buffer_init(rb, watermark, flags);

	return rb;

fail_all_buf:
	kfree(rb);

fail:
	return NULL;
}

#endif
Commit	Line	Data
76369139 FW	1	/*
	2	* Performance events ring-buffer code:
	3	*
	4	* Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
	5	* Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
	6	* Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
d36b6910	7	* Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
76369139 FW	8	*
	9	* For licensing details see kernel-base/COPYING
	10	*/
	11
	12	#include <linux/perf_event.h>
	13	#include <linux/vmalloc.h>
	14	#include <linux/slab.h>
	15
	16	#include "internal.h"
	17
	18	static bool perf_output_space(struct ring_buffer *rb, unsigned long tail,
	19	unsigned long offset, unsigned long head)
	20	{
dd9c086d SE	21	unsigned long sz = perf_data_size(rb);
dd9c086d SE	22	unsigned long mask = sz - 1;
76369139	23
dd9c086d SE	24	/*
	25	* check if user-writable
	26	* overwrite : over-write its own tail
	27	* !overwrite: buffer possibly drops events.
	28	*/
	29	if (rb->overwrite)
76369139 FW	30	return true;
76369139 FW	31
dd9c086d SE	32	/*
	33	* verify that payload is not bigger than buffer
	34	* otherwise masking logic may fail to detect
	35	* the "not enough space" condition
	36	*/
	37	if ((head - offset) > sz)
	38	return false;
76369139 FW	39
	40	offset = (offset - tail) & mask;
	41	head = (head - tail) & mask;
	42
	43	if ((int)(head - offset) < 0)
	44	return false;
	45
	46	return true;
	47	}
	48
	49	static void perf_output_wakeup(struct perf_output_handle *handle)
	50	{
	51	atomic_set(&handle->rb->poll, POLL_IN);
	52
a8b0ca17 PZ	53	handle->event->pending_wakeup = 1;
a8b0ca17 PZ	54	irq_work_queue(&handle->event->pending);
76369139 FW	55	}
	56
	57	/*
	58	* We need to ensure a later event_id doesn't publish a head when a former
	59	* event isn't done writing. However since we need to deal with NMIs we
	60	* cannot fully serialize things.
	61	*
	62	* We only publish the head (and generate a wakeup) when the outer-most
	63	* event completes.
	64	*/
	65	static void perf_output_get_handle(struct perf_output_handle *handle)
	66	{
	67	struct ring_buffer *rb = handle->rb;
	68
	69	preempt_disable();
	70	local_inc(&rb->nest);
	71	handle->wakeup = local_read(&rb->wakeup);
	72	}
	73
	74	static void perf_output_put_handle(struct perf_output_handle *handle)
	75	{
	76	struct ring_buffer *rb = handle->rb;
	77	unsigned long head;
	78
	79	again:
	80	head = local_read(&rb->head);
	81
	82	/*
	83	* IRQ/NMI can happen here, which means we can miss a head update.
	84	*/
	85
	86	if (!local_dec_and_test(&rb->nest))
	87	goto out;
	88
	89	/*
0fb024c4 PZ	90	* Since the mmap() consumer (userspace) can run on a different CPU:
	91	*
	92	* kernel user
	93	*
	94	* READ ->data_tail READ ->data_head
	95	* smp_mb() (A) smp_rmb() (C)
	96	* WRITE $data READ $data
	97	* smp_wmb() (B) smp_mb() (D)
	98	* STORE ->data_head WRITE ->data_tail
	99	*
	100	* Where A pairs with D, and B pairs with C.
	101	*
	102	* I don't think A needs to be a full barrier because we won't in fact
	103	* write data until we see the store from userspace. So we simply don't
	104	* issue the data WRITE until we observe it. Be conservative for now.
	105	*
	106	* OTOH, D needs to be a full barrier since it separates the data READ
	107	* from the tail WRITE.
	108	*
	109	* For B a WMB is sufficient since it separates two WRITEs, and for C
	110	* an RMB is sufficient since it separates two READs.
	111	*
	112	* See perf_output_begin().
76369139	113	*/
0fb024c4	114	smp_wmb();
76369139 FW	115	rb->user_page->data_head = head;
	116
	117	/*
	118	* Now check if we missed an update, rely on the (compiler)
	119	* barrier in atomic_dec_and_test() to re-read rb->head.
	120	*/
	121	if (unlikely(head != local_read(&rb->head))) {
	122	local_inc(&rb->nest);
	123	goto again;
	124	}
	125
	126	if (handle->wakeup != local_read(&rb->wakeup))
	127	perf_output_wakeup(handle);
	128
	129	out:
	130	preempt_enable();
	131	}
	132
	133	int perf_output_begin(struct perf_output_handle *handle,
a7ac67ea	134	struct perf_event *event, unsigned int size)
76369139 FW	135	{
	136	struct ring_buffer *rb;
	137	unsigned long tail, offset, head;
	138	int have_lost;
	139	struct perf_sample_data sample_data;
	140	struct {
	141	struct perf_event_header header;
	142	u64 id;
	143	u64 lost;
	144	} lost_event;
	145
	146	rcu_read_lock();
	147	/*
	148	* For inherited events we send all the output towards the parent.
	149	*/
	150	if (event->parent)
	151	event = event->parent;
	152
	153	rb = rcu_dereference(event->rb);
	154	if (!rb)
	155	goto out;
	156
	157	handle->rb = rb;
	158	handle->event = event;
76369139 FW	159
	160	if (!rb->nr_pages)
	161	goto out;
	162
	163	have_lost = local_read(&rb->lost);
	164	if (have_lost) {
	165	lost_event.header.size = sizeof(lost_event);
	166	perf_event_header__init_id(&lost_event.header, &sample_data,
	167	event);
	168	size += lost_event.header.size;
	169	}
	170
	171	perf_output_get_handle(handle);
	172
	173	do {
	174	/*
	175	* Userspace could choose to issue a mb() before updating the
	176	* tail pointer. So that all reads will be completed before the
	177	* write is issued.
0fb024c4 PZ	178	*
0fb024c4 PZ	179	* See perf_output_put_handle().
76369139 FW	180	*/
76369139 FW	181	tail = ACCESS_ONCE(rb->user_page->data_tail);
0fb024c4	182	smp_mb();
76369139 FW	183	offset = head = local_read(&rb->head);
	184	head += size;
	185	if (unlikely(!perf_output_space(rb, tail, offset, head)))
	186	goto fail;
	187	} while (local_cmpxchg(&rb->head, offset, head) != offset);
	188
	189	if (head - local_read(&rb->wakeup) > rb->watermark)
	190	local_add(rb->watermark, &rb->wakeup);
	191
	192	handle->page = offset >> (PAGE_SHIFT + page_order(rb));
	193	handle->page &= rb->nr_pages - 1;
	194	handle->size = offset & ((PAGE_SIZE << page_order(rb)) - 1);
	195	handle->addr = rb->data_pages[handle->page];
	196	handle->addr += handle->size;
	197	handle->size = (PAGE_SIZE << page_order(rb)) - handle->size;
	198
	199	if (have_lost) {
	200	lost_event.header.type = PERF_RECORD_LOST;
	201	lost_event.header.misc = 0;
	202	lost_event.id = event->id;
	203	lost_event.lost = local_xchg(&rb->lost, 0);
	204
	205	perf_output_put(handle, lost_event);
	206	perf_event__output_id_sample(event, handle, &sample_data);
	207	}
	208
	209	return 0;
	210
	211	fail:
	212	local_inc(&rb->lost);
	213	perf_output_put_handle(handle);
	214	out:
	215	rcu_read_unlock();
	216
	217	return -ENOSPC;
	218	}
	219
91d7753a	220	unsigned int perf_output_copy(struct perf_output_handle *handle,
76369139 FW	221	const void *buf, unsigned int len)
76369139 FW	222	{
91d7753a	223	return __output_copy(handle, buf, len);
76369139 FW	224	}
76369139 FW	225
5685e0ff JO	226	unsigned int perf_output_skip(struct perf_output_handle *handle,
	227	unsigned int len)
	228	{
	229	return __output_skip(handle, NULL, len);
	230	}
	231
76369139 FW	232	void perf_output_end(struct perf_output_handle *handle)
76369139 FW	233	{
76369139 FW	234	perf_output_put_handle(handle);
	235	rcu_read_unlock();
	236	}
	237
	238	static void
	239	ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
	240	{
	241	long max_size = perf_data_size(rb);
	242
	243	if (watermark)
	244	rb->watermark = min(max_size, watermark);
	245
	246	if (!rb->watermark)
	247	rb->watermark = max_size / 2;
	248
	249	if (flags & RING_BUFFER_WRITABLE)
dd9c086d SE	250	rb->overwrite = 0;
	251	else
	252	rb->overwrite = 1;
76369139 FW	253
76369139 FW	254	atomic_set(&rb->refcount, 1);
10c6db11 PZ	255
	256	INIT_LIST_HEAD(&rb->event_list);
	257	spin_lock_init(&rb->event_lock);
76369139 FW	258	}
	259
	260	#ifndef CONFIG_PERF_USE_VMALLOC
	261
	262	/*
	263	* Back perf_mmap() with regular GFP_KERNEL-0 pages.
	264	*/
	265
	266	struct page *
	267	perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
	268	{
	269	if (pgoff > rb->nr_pages)
	270	return NULL;
	271
	272	if (pgoff == 0)
	273	return virt_to_page(rb->user_page);
	274
	275	return virt_to_page(rb->data_pages[pgoff - 1]);
	276	}
	277
	278	static void *perf_mmap_alloc_page(int cpu)
	279	{
	280	struct page *page;
	281	int node;
	282
	283	node = (cpu == -1) ? cpu : cpu_to_node(cpu);
	284	page = alloc_pages_node(node, GFP_KERNEL \| __GFP_ZERO, 0);
	285	if (!page)
	286	return NULL;
	287
	288	return page_address(page);
	289	}
	290
	291	struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
	292	{
	293	struct ring_buffer *rb;
	294	unsigned long size;
	295	int i;
	296
	297	size = sizeof(struct ring_buffer);
	298	size += nr_pages * sizeof(void *);
	299
	300	rb = kzalloc(size, GFP_KERNEL);
	301	if (!rb)
	302	goto fail;
	303
	304	rb->user_page = perf_mmap_alloc_page(cpu);
	305	if (!rb->user_page)
	306	goto fail_user_page;
	307
	308	for (i = 0; i < nr_pages; i++) {
	309	rb->data_pages[i] = perf_mmap_alloc_page(cpu);
	310	if (!rb->data_pages[i])
	311	goto fail_data_pages;
	312	}
	313
	314	rb->nr_pages = nr_pages;
	315
	316	ring_buffer_init(rb, watermark, flags);
	317
	318	return rb;
	319
	320	fail_data_pages:
	321	for (i--; i >= 0; i--)
322	free_page((unsigned long)rb->data_pages[i]);
323
324	free_page((unsigned long)rb->user_page);
325
326	fail_user_page:
327	kfree(rb);
328
329	fail:
330	return NULL;
331	}
332
333	static void perf_mmap_free_page(unsigned long addr)
334	{
335	struct page page = virt_to_page((void )addr);
336
337	page->mapping = NULL;
338	__free_page(page);
339	}
340
341	void rb_free(struct ring_buffer *rb)
342	{
343	int i;
344
345	perf_mmap_free_page((unsigned long)rb->user_page);
346	for (i = 0; i < rb->nr_pages; i++)
347	perf_mmap_free_page((unsigned long)rb->data_pages[i]);
348	kfree(rb);
349	}
350
351	#else
5919b309 JO	352	static int data_page_nr(struct ring_buffer *rb)
	353	{
	354	return rb->nr_pages << page_order(rb);
	355	}
76369139 FW	356
	357	struct page *
	358	perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
	359	{
5919b309 JO	360	/* The '>' counts in the user page. */
5919b309 JO	361	if (pgoff > data_page_nr(rb))
76369139 FW	362	return NULL;
	363
	364	return vmalloc_to_page((void )rb->user_page + pgoff PAGE_SIZE);
	365	}
	366
	367	static void perf_mmap_unmark_page(void *addr)
	368	{
	369	struct page *page = vmalloc_to_page(addr);
	370
	371	page->mapping = NULL;
	372	}
	373
	374	static void rb_free_work(struct work_struct *work)
	375	{
	376	struct ring_buffer *rb;
	377	void *base;
	378	int i, nr;
	379
	380	rb = container_of(work, struct ring_buffer, work);
5919b309	381	nr = data_page_nr(rb);
76369139 FW	382
76369139 FW	383	base = rb->user_page;
5919b309 JO	384	/* The '<=' counts in the user page. */
5919b309 JO	385	for (i = 0; i <= nr; i++)
76369139 FW	386	perf_mmap_unmark_page(base + (i * PAGE_SIZE));
	387
	388	vfree(base);
	389	kfree(rb);
	390	}
	391
	392	void rb_free(struct ring_buffer *rb)
	393	{
	394	schedule_work(&rb->work);
	395	}
	396
	397	struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
	398	{
	399	struct ring_buffer *rb;
	400	unsigned long size;
	401	void *all_buf;
	402
	403	size = sizeof(struct ring_buffer);
	404	size += sizeof(void *);
	405
	406	rb = kzalloc(size, GFP_KERNEL);
	407	if (!rb)
	408	goto fail;
	409
	410	INIT_WORK(&rb->work, rb_free_work);
	411
	412	all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
	413	if (!all_buf)
	414	goto fail_all_buf;
	415
	416	rb->user_page = all_buf;
	417	rb->data_pages[0] = all_buf + PAGE_SIZE;
	418	rb->page_order = ilog2(nr_pages);
5919b309	419	rb->nr_pages = !!nr_pages;
76369139 FW	420
	421	ring_buffer_init(rb, watermark, flags);
	422
	423	return rb;
	424
	425	fail_all_buf:
	426	kfree(rb);
	427
	428	fail:
	429	return NULL;
	430	}
	431
	432	#endif