kernel/kfifo.c - LeafOS-Devices/android_kernel_samsung_universal7904 - Gitiles

 /*
  * A generic kernel FIFO implementation
  *
  * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  *
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/log2.h>
 #include <linux/uaccess.h>
 #include <linux/kfifo.h>

 /*
  * internal helper to calculate the unused elements in a fifo
  */
 static inline unsigned int kfifo_unused(struct __kfifo *fifo)
 {
 	return (fifo->mask + 1) - (fifo->in - fifo->out);
 }

 int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
 		size_t esize, gfp_t gfp_mask)
 {
 	/*
 	 * round down to the next power of 2, since our 'let the indices
 	 * wrap' technique works only in this case.
 	 */
 	if (!is_power_of_2(size))
 		size = rounddown_pow_of_two(size);

 	fifo->in = 0;
 	fifo->out = 0;
 	fifo->esize = esize;

 	if (size < 2) {
 		fifo->data = NULL;
 		fifo->mask = 0;
 		return -EINVAL;
 	}

 	fifo->data = kmalloc(size * esize, gfp_mask);

 	if (!fifo->data) {
 		fifo->mask = 0;
 		return -ENOMEM;
 	}
 	fifo->mask = size - 1;

 	return 0;
 }
 EXPORT_SYMBOL(__kfifo_alloc);

 void __kfifo_free(struct __kfifo *fifo)
 {
 	kfree(fifo->data);
 	fifo->in = 0;
 	fifo->out = 0;
 	fifo->esize = 0;
 	fifo->data = NULL;
 	fifo->mask = 0;
 }
 EXPORT_SYMBOL(__kfifo_free);

 int __kfifo_init(struct __kfifo *fifo, void *buffer,
 		unsigned int size, size_t esize)
 {
 	size /= esize;

 	if (!is_power_of_2(size))
 		size = rounddown_pow_of_two(size);

 	fifo->in = 0;
 	fifo->out = 0;
 	fifo->esize = esize;
 	fifo->data = buffer;

 	if (size < 2) {
 		fifo->mask = 0;
 		return -EINVAL;
 	}
 	fifo->mask = size - 1;

 	return 0;
 }
 EXPORT_SYMBOL(__kfifo_init);

 static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
 		unsigned int len, unsigned int off)
 {
 	unsigned int size = fifo->mask + 1;
 	unsigned int esize = fifo->esize;
 	unsigned int l;

 	off &= fifo->mask;
 	if (esize != 1) {
 		off *= esize;
 		size *= esize;
 		len *= esize;
 	}
 	l = min(len, size - off);

 	memcpy(fifo->data + off, src, l);
 	memcpy(fifo->data, src + l, len - l);
 	/*
 	 * make sure that the data in the fifo is up to date before
 	 * incrementing the fifo->in index counter
 	 */
 	smp_wmb();
 }

 unsigned int __kfifo_in(struct __kfifo *fifo,
 		const void *buf, unsigned int len)
 {
 	unsigned int l;

 	l = kfifo_unused(fifo);
 	if (len > l)
 		len = l;

 	kfifo_copy_in(fifo, buf, len, fifo->in);
 	fifo->in += len;
 	return len;
 }
 EXPORT_SYMBOL(__kfifo_in);

 static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
 		unsigned int len, unsigned int off)
 {
 	unsigned int size = fifo->mask + 1;
 	unsigned int esize = fifo->esize;
 	unsigned int l;

 	off &= fifo->mask;
 	if (esize != 1) {
 		off *= esize;
 		size *= esize;
 		len *= esize;
 	}
 	l = min(len, size - off);

 	memcpy(dst, fifo->data + off, l);
 	memcpy(dst + l, fifo->data, len - l);
 	/*
 	 * make sure that the data is copied before
 	 * incrementing the fifo->out index counter
 	 */
 	smp_wmb();
 }

 unsigned int __kfifo_out_peek(struct __kfifo *fifo,
 		void *buf, unsigned int len)
 {
 	unsigned int l;

 	l = fifo->in - fifo->out;
 	if (len > l)
 		len = l;

 	kfifo_copy_out(fifo, buf, len, fifo->out);
 	return len;
 }
 EXPORT_SYMBOL(__kfifo_out_peek);

 unsigned int __kfifo_out(struct __kfifo *fifo,
 		void *buf, unsigned int len)
 {
 	len = __kfifo_out_peek(fifo, buf, len);
 	fifo->out += len;
 	return len;
 }
 EXPORT_SYMBOL(__kfifo_out);

 static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
 	const void __user *from, unsigned int len, unsigned int off,
 	unsigned int *copied)
 {
 	unsigned int size = fifo->mask + 1;
 	unsigned int esize = fifo->esize;
 	unsigned int l;
 	unsigned long ret;

 	off &= fifo->mask;
 	if (esize != 1) {
 		off *= esize;
 		size *= esize;
 		len *= esize;
 	}
 	l = min(len, size - off);

 	ret = copy_from_user(fifo->data + off, from, l);
 	if (unlikely(ret))
 		ret = DIV_ROUND_UP(ret + len - l, esize);
 	else {
 		ret = copy_from_user(fifo->data, from + l, len - l);
 		if (unlikely(ret))
 			ret = DIV_ROUND_UP(ret, esize);
 	}
 	/*
 	 * make sure that the data in the fifo is up to date before
 	 * incrementing the fifo->in index counter
 	 */
 	smp_wmb();
 	*copied = len - ret;
 	/* return the number of elements which are not copied */
 	return ret;
 }

 int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
 		unsigned long len, unsigned int *copied)
 {
 	unsigned int l;
 	unsigned long ret;
 	unsigned int esize = fifo->esize;
 	int err;

 	if (esize != 1)
 		len /= esize;

 	l = kfifo_unused(fifo);
 	if (len > l)
 		len = l;

 	ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
 	if (unlikely(ret)) {
 		len -= ret;
 		err = -EFAULT;
 	} else
 		err = 0;
 	fifo->in += len;
 	return err;
 }
 EXPORT_SYMBOL(__kfifo_from_user);

 static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
 		unsigned int len, unsigned int off, unsigned int *copied)
 {
 	unsigned int l;
 	unsigned long ret;
 	unsigned int size = fifo->mask + 1;
 	unsigned int esize = fifo->esize;

 	off &= fifo->mask;
 	if (esize != 1) {
 		off *= esize;
 		size *= esize;
 		len *= esize;
 	}
 	l = min(len, size - off);

 	ret = copy_to_user(to, fifo->data + off, l);
 	if (unlikely(ret))
 		ret = DIV_ROUND_UP(ret + len - l, esize);
 	else {
 		ret = copy_to_user(to + l, fifo->data, len - l);
 		if (unlikely(ret))
 			ret = DIV_ROUND_UP(ret, esize);
 	}
 	/*
 	 * make sure that the data is copied before
 	 * incrementing the fifo->out index counter
 	 */
 	smp_wmb();
 	*copied = len - ret;
 	/* return the number of elements which are not copied */
 	return ret;
 }

 int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
 		unsigned long len, unsigned int *copied)
 {
 	unsigned int l;
 	unsigned long ret;
 	unsigned int esize = fifo->esize;
 	int err;

 	if (esize != 1)
 		len /= esize;

 	l = fifo->in - fifo->out;
 	if (len > l)
 		len = l;
 	ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
 	if (unlikely(ret)) {
 		len -= ret;
 		err = -EFAULT;
 	} else
 		err = 0;
 	fifo->out += len;
 	return err;
 }
 EXPORT_SYMBOL(__kfifo_to_user);

 static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
 		int nents, unsigned int len)
 {
 	int n;
 	unsigned int l;
 	unsigned int off;
 	struct page *page;

 	if (!nents)
 		return 0;

 	if (!len)
 		return 0;

 	n = 0;
 	page = virt_to_page(buf);
 	off = offset_in_page(buf);
 	l = 0;

 	while (len >= l + PAGE_SIZE - off) {
 		struct page *npage;

 		l += PAGE_SIZE;
 		buf += PAGE_SIZE;
 		npage = virt_to_page(buf);
 		if (page_to_phys(page) != page_to_phys(npage) - l) {
 			sg_set_page(sgl, page, l - off, off);
 			sgl = sg_next(sgl);
 			if (++n == nents || sgl == NULL)
 				return n;
 			page = npage;
 			len -= l - off;
 			l = off = 0;
 		}
 	}
 	sg_set_page(sgl, page, len, off);
 	return n + 1;
 }

 static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
 		int nents, unsigned int len, unsigned int off)
 {
 	unsigned int size = fifo->mask + 1;
 	unsigned int esize = fifo->esize;
 	unsigned int l;
 	unsigned int n;

 	off &= fifo->mask;
 	if (esize != 1) {
 		off *= esize;
 		size *= esize;
 		len *= esize;
 	}
 	l = min(len, size - off);

 	n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
 	n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);

 	if (n)
 		sg_mark_end(sgl + n - 1);
 	return n;
 }

 unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
 		struct scatterlist *sgl, int nents, unsigned int len)
 {
 	unsigned int l;

 	l = kfifo_unused(fifo);
 	if (len > l)
 		len = l;

 	return setup_sgl(fifo, sgl, nents, len, fifo->in);
 }
 EXPORT_SYMBOL(__kfifo_dma_in_prepare);

 unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
 		struct scatterlist *sgl, int nents, unsigned int len)
 {
 	unsigned int l;

 	l = fifo->in - fifo->out;
 	if (len > l)
 		len = l;

 	return setup_sgl(fifo, sgl, nents, len, fifo->out);
 }
 EXPORT_SYMBOL(__kfifo_dma_out_prepare);

 unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
 {
 	unsigned int max = (1 << (recsize << 3)) - 1;

 	if (len > max)
 		return max;
 	return len;
 }

 #define	__KFIFO_PEEK(data, out, mask) \
 	((data)[(out) & (mask)])
 /*
  * __kfifo_peek_n internal helper function for determinate the length of
  * the next record in the fifo
  */
 static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
 {
 	unsigned int l;
 	unsigned int mask = fifo->mask;
 	unsigned char *data = fifo->data;

 	l = __KFIFO_PEEK(data, fifo->out, mask);

 	if (--recsize)
 		l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;

 	return l;
 }

 #define	__KFIFO_POKE(data, in, mask, val) \
 	( \
 	(data)[(in) & (mask)] = (unsigned char)(val) \
 	)

 /*
  * __kfifo_poke_n internal helper function for storeing the length of
  * the record into the fifo
  */
 static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
 {
 	unsigned int mask = fifo->mask;
 	unsigned char *data = fifo->data;

 	__KFIFO_POKE(data, fifo->in, mask, n);

 	if (recsize > 1)
 		__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
 }

 unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
 {
 	return __kfifo_peek_n(fifo, recsize);
 }
 EXPORT_SYMBOL(__kfifo_len_r);

 unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
 		unsigned int len, size_t recsize)
 {
 	if (len + recsize > kfifo_unused(fifo))
 		return 0;

 	__kfifo_poke_n(fifo, len, recsize);

 	kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
 	fifo->in += len + recsize;
 	return len;
 }
 EXPORT_SYMBOL(__kfifo_in_r);

 static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
 	void *buf, unsigned int len, size_t recsize, unsigned int *n)
 {
 	*n = __kfifo_peek_n(fifo, recsize);

 	if (len > *n)
 		len = *n;

 	kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
 	return len;
 }

 unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
 		unsigned int len, size_t recsize)
 {
 	unsigned int n;

 	if (fifo->in == fifo->out)
 		return 0;

 	return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
 }
 EXPORT_SYMBOL(__kfifo_out_peek_r);

 unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
 		unsigned int len, size_t recsize)
 {
 	unsigned int n;

 	if (fifo->in == fifo->out)
 		return 0;

 	len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
 	fifo->out += n + recsize;
 	return len;
 }
 EXPORT_SYMBOL(__kfifo_out_r);

 int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
 	unsigned long len, unsigned int *copied, size_t recsize)
 {
 	unsigned long ret;

 	len = __kfifo_max_r(len, recsize);

 	if (len + recsize > kfifo_unused(fifo)) {
 		*copied = 0;
 		return 0;
 	}

 	__kfifo_poke_n(fifo, len, recsize);

 	ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
 	if (unlikely(ret)) {
 		*copied = 0;
 		return -EFAULT;
 	}
 	fifo->in += len + recsize;
 	return 0;
 }
 EXPORT_SYMBOL(__kfifo_from_user_r);

 int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
 	unsigned long len, unsigned int *copied, size_t recsize)
 {
 	unsigned long ret;
 	unsigned int n;

 	if (fifo->in == fifo->out) {
 		*copied = 0;
 		return 0;
 	}

 	n = __kfifo_peek_n(fifo, recsize);
 	if (len > n)
 		len = n;

 	ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
 	if (unlikely(ret)) {
 		*copied = 0;
 		return -EFAULT;
 	}
 	fifo->out += n + recsize;
 	return 0;
 }
 EXPORT_SYMBOL(__kfifo_to_user_r);

 unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
 	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
 {
 	if (!nents)
 		BUG();

 	len = __kfifo_max_r(len, recsize);

 	if (len + recsize > kfifo_unused(fifo))
 		return 0;

 	return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
 }
 EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);

 void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
 	unsigned int len, size_t recsize)
 {
 	len = __kfifo_max_r(len, recsize);
 	__kfifo_poke_n(fifo, len, recsize);
 	fifo->in += len + recsize;
 }
 EXPORT_SYMBOL(__kfifo_dma_in_finish_r);

 unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
 	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
 {
 	if (!nents)
 		BUG();

 	len = __kfifo_max_r(len, recsize);

 	if (len + recsize > fifo->in - fifo->out)
 		return 0;

 	return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
 }
 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);

 void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
 {
 	unsigned int len;

 	len = __kfifo_peek_n(fifo, recsize);
 	fifo->out += len + recsize;
 }
 EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
	/*
	* A generic kernel FIFO implementation
	*
	* Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/err.h>
	#include <linux/log2.h>
	#include <linux/uaccess.h>
	#include <linux/kfifo.h>

	/*
	* internal helper to calculate the unused elements in a fifo
	*/
	static inline unsigned int kfifo_unused(struct __kfifo *fifo)
	{
	return (fifo->mask + 1) - (fifo->in - fifo->out);
	}

	int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
	size_t esize, gfp_t gfp_mask)
	{
	/*
	* round down to the next power of 2, since our 'let the indices
	* wrap' technique works only in this case.
	*/
	if (!is_power_of_2(size))
	size = rounddown_pow_of_two(size);

	fifo->in = 0;
	fifo->out = 0;
	fifo->esize = esize;

	if (size < 2) {
	fifo->data = NULL;
	fifo->mask = 0;
	return -EINVAL;
	}

	fifo->data = kmalloc(size * esize, gfp_mask);

	if (!fifo->data) {
	fifo->mask = 0;
	return -ENOMEM;
	}
	fifo->mask = size - 1;

	return 0;
	}
	EXPORT_SYMBOL(__kfifo_alloc);

	void __kfifo_free(struct __kfifo *fifo)
	{
	kfree(fifo->data);
	fifo->in = 0;
	fifo->out = 0;
	fifo->esize = 0;
	fifo->data = NULL;
	fifo->mask = 0;
	}
	EXPORT_SYMBOL(__kfifo_free);

	int __kfifo_init(struct __kfifo fifo, void buffer,
	unsigned int size, size_t esize)
	{
	size /= esize;

	if (!is_power_of_2(size))
	size = rounddown_pow_of_two(size);

	fifo->in = 0;
	fifo->out = 0;
	fifo->esize = esize;
	fifo->data = buffer;

	if (size < 2) {
	fifo->mask = 0;
	return -EINVAL;
	}
	fifo->mask = size - 1;

	return 0;
	}
	EXPORT_SYMBOL(__kfifo_init);

	static void kfifo_copy_in(struct __kfifo fifo, const void src,
	unsigned int len, unsigned int off)
	{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;

	off &= fifo->mask;
	if (esize != 1) {
	off *= esize;
	size *= esize;
	len *= esize;
	}
	l = min(len, size - off);

	memcpy(fifo->data + off, src, l);
	memcpy(fifo->data, src + l, len - l);
	/*
	* make sure that the data in the fifo is up to date before
	* incrementing the fifo->in index counter
	*/
	smp_wmb();
	}

	unsigned int __kfifo_in(struct __kfifo *fifo,
	const void *buf, unsigned int len)
	{
	unsigned int l;

	l = kfifo_unused(fifo);
	if (len > l)
	len = l;

	kfifo_copy_in(fifo, buf, len, fifo->in);
	fifo->in += len;
	return len;
	}
	EXPORT_SYMBOL(__kfifo_in);

	static void kfifo_copy_out(struct __kfifo fifo, void dst,
	unsigned int len, unsigned int off)
	{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;

	off &= fifo->mask;
	if (esize != 1) {
	off *= esize;
	size *= esize;
	len *= esize;
	}
	l = min(len, size - off);

	memcpy(dst, fifo->data + off, l);
	memcpy(dst + l, fifo->data, len - l);
	/*
	* make sure that the data is copied before
	* incrementing the fifo->out index counter
	*/
	smp_wmb();
	}

	unsigned int __kfifo_out_peek(struct __kfifo *fifo,
	void *buf, unsigned int len)
	{
	unsigned int l;

	l = fifo->in - fifo->out;
	if (len > l)
	len = l;

	kfifo_copy_out(fifo, buf, len, fifo->out);
	return len;
	}
	EXPORT_SYMBOL(__kfifo_out_peek);

	unsigned int __kfifo_out(struct __kfifo *fifo,
	void *buf, unsigned int len)
	{
	len = __kfifo_out_peek(fifo, buf, len);
	fifo->out += len;
	return len;
	}
	EXPORT_SYMBOL(__kfifo_out);

	static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
	const void __user *from, unsigned int len, unsigned int off,
	unsigned int *copied)
	{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;
	unsigned long ret;

	off &= fifo->mask;
	if (esize != 1) {
	off *= esize;
	size *= esize;
	len *= esize;
	}
	l = min(len, size - off);

	ret = copy_from_user(fifo->data + off, from, l);
	if (unlikely(ret))
	ret = DIV_ROUND_UP(ret + len - l, esize);
	else {
	ret = copy_from_user(fifo->data, from + l, len - l);
	if (unlikely(ret))
	ret = DIV_ROUND_UP(ret, esize);
	}
	/*
	* make sure that the data in the fifo is up to date before
	* incrementing the fifo->in index counter
	*/
	smp_wmb();
	*copied = len - ret;
	/* return the number of elements which are not copied */
	return ret;
	}

	int __kfifo_from_user(struct __kfifo fifo, const void __user from,
	unsigned long len, unsigned int *copied)
	{
	unsigned int l;
	unsigned long ret;
	unsigned int esize = fifo->esize;
	int err;

	if (esize != 1)
	len /= esize;

	l = kfifo_unused(fifo);
	if (len > l)
	len = l;

	ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
	if (unlikely(ret)) {
	len -= ret;
	err = -EFAULT;
	} else
	err = 0;
	fifo->in += len;
	return err;
	}
	EXPORT_SYMBOL(__kfifo_from_user);

	static unsigned long kfifo_copy_to_user(struct __kfifo fifo, void __user to,
	unsigned int len, unsigned int off, unsigned int *copied)
	{
	unsigned int l;
	unsigned long ret;
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;

	off &= fifo->mask;
	if (esize != 1) {
	off *= esize;
	size *= esize;
	len *= esize;
	}
	l = min(len, size - off);

	ret = copy_to_user(to, fifo->data + off, l);
	if (unlikely(ret))
	ret = DIV_ROUND_UP(ret + len - l, esize);
	else {
	ret = copy_to_user(to + l, fifo->data, len - l);
	if (unlikely(ret))
	ret = DIV_ROUND_UP(ret, esize);
	}
	/*
	* make sure that the data is copied before
	* incrementing the fifo->out index counter
	*/
	smp_wmb();
	*copied = len - ret;
	/* return the number of elements which are not copied */
	return ret;
	}

	int __kfifo_to_user(struct __kfifo fifo, void __user to,
	unsigned long len, unsigned int *copied)
	{
	unsigned int l;
	unsigned long ret;
	unsigned int esize = fifo->esize;
	int err;

	if (esize != 1)
	len /= esize;

	l = fifo->in - fifo->out;
	if (len > l)
	len = l;
	ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
	if (unlikely(ret)) {
	len -= ret;
	err = -EFAULT;
	} else
	err = 0;
	fifo->out += len;
	return err;
	}
	EXPORT_SYMBOL(__kfifo_to_user);

	static int setup_sgl_buf(struct scatterlist sgl, void buf,
	int nents, unsigned int len)
	{
	int n;
	unsigned int l;
	unsigned int off;
	struct page *page;

	if (!nents)
	return 0;

	if (!len)
	return 0;

	n = 0;
	page = virt_to_page(buf);
	off = offset_in_page(buf);
	l = 0;

	while (len >= l + PAGE_SIZE - off) {
	struct page *npage;

	l += PAGE_SIZE;
	buf += PAGE_SIZE;
	npage = virt_to_page(buf);
	if (page_to_phys(page) != page_to_phys(npage) - l) {
	sg_set_page(sgl, page, l - off, off);
	sgl = sg_next(sgl);
	if (++n == nents \|\| sgl == NULL)
	return n;
	page = npage;
	len -= l - off;
	l = off = 0;
	}
	}
	sg_set_page(sgl, page, len, off);
	return n + 1;
	}

	static unsigned int setup_sgl(struct __kfifo fifo, struct scatterlist sgl,
	int nents, unsigned int len, unsigned int off)
	{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;
	unsigned int n;

	off &= fifo->mask;
	if (esize != 1) {
	off *= esize;
	size *= esize;
	len *= esize;
	}
	l = min(len, size - off);

	n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
	n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);

	if (n)
	sg_mark_end(sgl + n - 1);
	return n;
	}

	unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
	struct scatterlist *sgl, int nents, unsigned int len)
	{
	unsigned int l;

	l = kfifo_unused(fifo);
	if (len > l)
	len = l;

	return setup_sgl(fifo, sgl, nents, len, fifo->in);
	}
	EXPORT_SYMBOL(__kfifo_dma_in_prepare);

	unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
	struct scatterlist *sgl, int nents, unsigned int len)
	{
	unsigned int l;

	l = fifo->in - fifo->out;
	if (len > l)
	len = l;

	return setup_sgl(fifo, sgl, nents, len, fifo->out);
	}
	EXPORT_SYMBOL(__kfifo_dma_out_prepare);

	unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
	{
	unsigned int max = (1 << (recsize << 3)) - 1;

	if (len > max)
	return max;
	return len;
	}

	#define __KFIFO_PEEK(data, out, mask) \
	((data)[(out) & (mask)])
	/*
	* __kfifo_peek_n internal helper function for determinate the length of
	* the next record in the fifo
	*/
	static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
	{
	unsigned int l;
	unsigned int mask = fifo->mask;
	unsigned char *data = fifo->data;

	l = __KFIFO_PEEK(data, fifo->out, mask);

	if (--recsize)
	l \|= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;

	return l;
	}

	#define __KFIFO_POKE(data, in, mask, val) \
	( \
	(data)[(in) & (mask)] = (unsigned char)(val) \
	)

	/*
	* __kfifo_poke_n internal helper function for storeing the length of
	* the record into the fifo
	*/
	static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
	{
	unsigned int mask = fifo->mask;
	unsigned char *data = fifo->data;

	__KFIFO_POKE(data, fifo->in, mask, n);

	if (recsize > 1)
	__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
	}

	unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
	{
	return __kfifo_peek_n(fifo, recsize);
	}
	EXPORT_SYMBOL(__kfifo_len_r);

	unsigned int __kfifo_in_r(struct __kfifo fifo, const void buf,
	unsigned int len, size_t recsize)
	{
	if (len + recsize > kfifo_unused(fifo))
	return 0;

	__kfifo_poke_n(fifo, len, recsize);

	kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
	fifo->in += len + recsize;
	return len;
	}
	EXPORT_SYMBOL(__kfifo_in_r);

	static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
	void buf, unsigned int len, size_t recsize, unsigned int n)
	{
	*n = __kfifo_peek_n(fifo, recsize);

	if (len > *n)
	len = *n;

	kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
	return len;
	}

	unsigned int __kfifo_out_peek_r(struct __kfifo fifo, void buf,
	unsigned int len, size_t recsize)
	{
	unsigned int n;

	if (fifo->in == fifo->out)
	return 0;

	return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
	}
	EXPORT_SYMBOL(__kfifo_out_peek_r);

	unsigned int __kfifo_out_r(struct __kfifo fifo, void buf,
	unsigned int len, size_t recsize)
	{
	unsigned int n;

	if (fifo->in == fifo->out)
	return 0;

	len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
	fifo->out += n + recsize;
	return len;
	}
	EXPORT_SYMBOL(__kfifo_out_r);

	int __kfifo_from_user_r(struct __kfifo fifo, const void __user from,
	unsigned long len, unsigned int *copied, size_t recsize)
	{
	unsigned long ret;

	len = __kfifo_max_r(len, recsize);

	if (len + recsize > kfifo_unused(fifo)) {
	*copied = 0;
	return 0;
	}

	__kfifo_poke_n(fifo, len, recsize);

	ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
	if (unlikely(ret)) {
	*copied = 0;
	return -EFAULT;
	}
	fifo->in += len + recsize;
	return 0;
	}
	EXPORT_SYMBOL(__kfifo_from_user_r);

	int __kfifo_to_user_r(struct __kfifo fifo, void __user to,
	unsigned long len, unsigned int *copied, size_t recsize)
	{
	unsigned long ret;
	unsigned int n;

	if (fifo->in == fifo->out) {
	*copied = 0;
	return 0;
	}

	n = __kfifo_peek_n(fifo, recsize);
	if (len > n)
	len = n;

	ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
	if (unlikely(ret)) {
	*copied = 0;
	return -EFAULT;
	}
	fifo->out += n + recsize;
	return 0;
	}
	EXPORT_SYMBOL(__kfifo_to_user_r);

	unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
	{
	if (!nents)
	BUG();

	len = __kfifo_max_r(len, recsize);

	if (len + recsize > kfifo_unused(fifo))
	return 0;

	return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
	}
	EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);

	void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
	unsigned int len, size_t recsize)
	{
	len = __kfifo_max_r(len, recsize);
	__kfifo_poke_n(fifo, len, recsize);
	fifo->in += len + recsize;
	}
	EXPORT_SYMBOL(__kfifo_dma_in_finish_r);

	unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
	{
	if (!nents)
	BUG();

	len = __kfifo_max_r(len, recsize);

	if (len + recsize > fifo->in - fifo->out)
	return 0;

	return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
	}
	EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);

	void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
	{
	unsigned int len;

	len = __kfifo_peek_n(fifo, recsize);
	fifo->out += len + recsize;
	}
	EXPORT_SYMBOL(__kfifo_dma_out_finish_r);