Message-Id: <1281422440-23455-3-git-send-email-stefani@seibold.net>
Date:	Tue, 10 Aug 2010 08:40:38 +0200
From:	stefani@...bold.net
To:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	andi@...stfloor.org, gregkh@...e.de, alan@...rguk.ukuu.org.uk,
	tytso@....edu, iws@...o.caltech.edu
Cc:	stefani@...bold.net
Subject: [PATCH 2/4] add the new generic kfifo API

From: Stefani Seibold <stefani@...bold.net>

add the new version of the kfifo API files kfifo.c and kfifo.h.

Signed-off-by: Stefani Seibold <stefani@...bold.net>
---
 include/linux/kfifo.h | 1459 ++++++++++++++++++++++++++++---------------------
 kernel/kfifo.c        | 1046 ++++++++++++++++++++---------------
 2 files changed, 1445 insertions(+), 1060 deletions(-)
 rewrite include/linux/kfifo.h (87%)
 rewrite kernel/kfifo.c (87%)

diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
dissimilarity index 87%
index 9fad052..311f875 100644
--- a/include/linux/kfifo.h
+++ b/include/linux/kfifo.h
@@ -1,615 +1,844 @@
-/*
- * A generic kernel FIFO implementation.
- *
- * Copyright (C) 2009 Stefani Seibold <stefani@...bold.net>
- * Copyright (C) 2004 Stelian Pop <stelian@...ies.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.
- *
- */
-
-/*
- * Howto porting drivers to the new generic fifo API:
- *
- * - Modify the declaration of the "struct kfifo *" object into a
- *   in-place "struct kfifo" object
- * - Init the in-place object with kfifo_alloc() or kfifo_init()
- *   Note: The address of the in-place "struct kfifo" object must be
- *   passed as the first argument to this functions
- * - Replace the use of __kfifo_put into kfifo_in and __kfifo_get
- *   into kfifo_out
- * - Replace the use of kfifo_put into kfifo_in_locked and kfifo_get
- *   into kfifo_out_locked
- *   Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc
- *   must be passed now to the kfifo_in_locked and kfifo_out_locked
- *   as the last parameter.
- * - All formerly name __kfifo_* functions has been renamed into kfifo_*
- */
-
-#ifndef _LINUX_KFIFO_H
-#define _LINUX_KFIFO_H
-
-#include <linux/kernel.h>
-#include <linux/spinlock.h>
-
-struct kfifo {
-	unsigned char *buffer;	/* the buffer holding the data */
-	unsigned int size;	/* the size of the allocated buffer */
-	unsigned int in;	/* data is added at offset (in % size) */
-	unsigned int out;	/* data is extracted from off. (out % size) */
-};
-
-/*
- * Macros for declaration and initialization of the kfifo datatype
- */
-
-/* helper macro */
-#define __kfifo_initializer(s, b) \
-	(struct kfifo) { \
-		.size	= s, \
-		.in	= 0, \
-		.out	= 0, \
-		.buffer = b \
-	}
-
-/**
- * DECLARE_KFIFO - macro to declare a kfifo and the associated buffer
- * @name: name of the declared kfifo datatype
- * @size: size of the fifo buffer. Must be a power of two.
- *
- * Note1: the macro can be used inside struct or union declaration
- * Note2: the macro creates two objects:
- *  A kfifo object with the given name and a buffer for the kfifo
- *  object named name##kfifo_buffer
- */
-#define DECLARE_KFIFO(name, size) \
-union { \
-	struct kfifo name; \
-	unsigned char name##kfifo_buffer[size + sizeof(struct kfifo)]; \
-}
-
-/**
- * INIT_KFIFO - Initialize a kfifo declared by DECLARE_KFIFO
- * @name: name of the declared kfifo datatype
- */
-#define INIT_KFIFO(name) \
-	name = __kfifo_initializer(sizeof(name##kfifo_buffer) - \
-				sizeof(struct kfifo), \
-				name##kfifo_buffer + sizeof(struct kfifo))
-
-/**
- * DEFINE_KFIFO - macro to define and initialize a kfifo
- * @name: name of the declared kfifo datatype
- * @size: size of the fifo buffer. Must be a power of two.
- *
- * Note1: the macro can be used for global and local kfifo data type variables
- * Note2: the macro creates two objects:
- *  A kfifo object with the given name and a buffer for the kfifo
- *  object named name##kfifo_buffer
- */
-#define DEFINE_KFIFO(name, size) \
-	unsigned char name##kfifo_buffer[size]; \
-	struct kfifo name = __kfifo_initializer(size, name##kfifo_buffer)
-
-extern void kfifo_init(struct kfifo *fifo, void *buffer,
-			unsigned int size);
-extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size,
-			gfp_t gfp_mask);
-extern void kfifo_free(struct kfifo *fifo);
-extern unsigned int kfifo_in(struct kfifo *fifo,
-				const void *from, unsigned int len);
-extern __must_check unsigned int kfifo_out(struct kfifo *fifo,
-				void *to, unsigned int len);
-extern __must_check unsigned int kfifo_out_peek(struct kfifo *fifo,
-				void *to, unsigned int len, unsigned offset);
-
-/**
- * kfifo_initialized - Check if kfifo is initialized.
- * @fifo: fifo to check
- * Return %true if FIFO is initialized, otherwise %false.
- * Assumes the fifo was 0 before.
- */
-static inline bool kfifo_initialized(struct kfifo *fifo)
-{
-	return fifo->buffer != NULL;
-}
-
-/**
- * kfifo_reset - removes the entire FIFO contents
- * @fifo: the fifo to be emptied.
- */
-static inline void kfifo_reset(struct kfifo *fifo)
-{
-	fifo->in = fifo->out = 0;
-}
-
-/**
- * kfifo_reset_out - skip FIFO contents
- * @fifo: the fifo to be emptied.
- */
-static inline void kfifo_reset_out(struct kfifo *fifo)
-{
-	smp_mb();
-	fifo->out = fifo->in;
-}
-
-/**
- * kfifo_size - returns the size of the fifo in bytes
- * @fifo: the fifo to be used.
- */
-static inline __must_check unsigned int kfifo_size(struct kfifo *fifo)
-{
-	return fifo->size;
-}
-
-/**
- * kfifo_len - returns the number of used bytes in the FIFO
- * @fifo: the fifo to be used.
- */
-static inline unsigned int kfifo_len(struct kfifo *fifo)
-{
-	register unsigned int	out;
-
-	out = fifo->out;
-	smp_rmb();
-	return fifo->in - out;
-}
-
-/**
- * kfifo_is_empty - returns true if the fifo is empty
- * @fifo: the fifo to be used.
- */
-static inline __must_check int kfifo_is_empty(struct kfifo *fifo)
-{
-	return fifo->in == fifo->out;
-}
-
-/**
- * kfifo_is_full - returns true if the fifo is full
- * @fifo: the fifo to be used.
- */
-static inline __must_check int kfifo_is_full(struct kfifo *fifo)
-{
-	return kfifo_len(fifo) == kfifo_size(fifo);
-}
-
-/**
- * kfifo_avail - returns the number of bytes available in the FIFO
- * @fifo: the fifo to be used.
- */
-static inline __must_check unsigned int kfifo_avail(struct kfifo *fifo)
-{
-	return kfifo_size(fifo) - kfifo_len(fifo);
-}
-
-/**
- * kfifo_in_locked - puts some data into the FIFO using a spinlock for locking
- * @fifo: the fifo to be used.
- * @from: the data to be added.
- * @n: the length of the data to be added.
- * @lock: pointer to the spinlock to use for locking.
- *
- * This function copies at most @n bytes from the @from buffer into
- * the FIFO depending on the free space, and returns the number of
- * bytes copied.
- */
-static inline unsigned int kfifo_in_locked(struct kfifo *fifo,
-		const void *from, unsigned int n, spinlock_t *lock)
-{
-	unsigned long flags;
-	unsigned int ret;
-
-	spin_lock_irqsave(lock, flags);
-
-	ret = kfifo_in(fifo, from, n);
-
-	spin_unlock_irqrestore(lock, flags);
-
-	return ret;
-}
-
-/**
- * kfifo_out_locked - gets some data from the FIFO using a spinlock for locking
- * @fifo: the fifo to be used.
- * @to: where the data must be copied.
- * @n: the size of the destination buffer.
- * @lock: pointer to the spinlock to use for locking.
- *
- * This function copies at most @n bytes from the FIFO into the
- * @to buffer and returns the number of copied bytes.
- */
-static inline __must_check unsigned int kfifo_out_locked(struct kfifo *fifo,
-	void *to, unsigned int n, spinlock_t *lock)
-{
-	unsigned long flags;
-	unsigned int ret;
-
-	spin_lock_irqsave(lock, flags);
-
-	ret = kfifo_out(fifo, to, n);
-
-	spin_unlock_irqrestore(lock, flags);
-
-	return ret;
-}
-
-extern void kfifo_skip(struct kfifo *fifo, unsigned int len);
-
-extern __must_check int kfifo_from_user(struct kfifo *fifo,
-	const void __user *from, unsigned int n, unsigned *lenout);
-
-extern __must_check int kfifo_to_user(struct kfifo *fifo,
-	void __user *to, unsigned int n, unsigned *lenout);
-
-/*
- * __kfifo_add_out internal helper function for updating the out offset
- */
-static inline void __kfifo_add_out(struct kfifo *fifo,
-				unsigned int off)
-{
-	smp_mb();
-	fifo->out += off;
-}
-
-/*
- * __kfifo_add_in internal helper function for updating the in offset
- */
-static inline void __kfifo_add_in(struct kfifo *fifo,
-				unsigned int off)
-{
-	smp_wmb();
-	fifo->in += off;
-}
-
-/*
- * __kfifo_off internal helper function for calculating the index of a
- * given offeset
- */
-static inline unsigned int __kfifo_off(struct kfifo *fifo, unsigned int off)
-{
-	return off & (fifo->size - 1);
-}
-
-/*
- * __kfifo_peek_n internal helper function for determinate the length of
- * the next record in the fifo
- */
-static inline unsigned int __kfifo_peek_n(struct kfifo *fifo,
-				unsigned int recsize)
-{
-#define __KFIFO_GET(fifo, off, shift) \
-	((fifo)->buffer[__kfifo_off((fifo), (fifo)->out+(off))] << (shift))
-
-	unsigned int l;
-
-	l = __KFIFO_GET(fifo, 0, 0);
-
-	if (--recsize)
-		l |= __KFIFO_GET(fifo, 1, 8);
-
-	return l;
-#undef	__KFIFO_GET
-}
-
-/*
- * __kfifo_poke_n internal helper function for storing the length of
- * the next record into the fifo
- */
-static inline void __kfifo_poke_n(struct kfifo *fifo,
-			unsigned int recsize, unsigned int n)
-{
-#define __KFIFO_PUT(fifo, off, val, shift) \
-		( \
-		(fifo)->buffer[__kfifo_off((fifo), (fifo)->in+(off))] = \
-		(unsigned char)((val) >> (shift)) \
-		)
-
-	__KFIFO_PUT(fifo, 0, n, 0);
-
-	if (--recsize)
-		__KFIFO_PUT(fifo, 1, n, 8);
-#undef	__KFIFO_PUT
-}
-
-/*
- * __kfifo_in_... internal functions for put date into the fifo
- * do not call it directly, use kfifo_in_rec() instead
- */
-extern unsigned int __kfifo_in_n(struct kfifo *fifo,
-	const void *from, unsigned int n, unsigned int recsize);
-
-extern unsigned int __kfifo_in_generic(struct kfifo *fifo,
-	const void *from, unsigned int n, unsigned int recsize);
-
-static inline unsigned int __kfifo_in_rec(struct kfifo *fifo,
-	const void *from, unsigned int n, unsigned int recsize)
-{
-	unsigned int ret;
-
-	ret = __kfifo_in_n(fifo, from, n, recsize);
-
-	if (likely(ret == 0)) {
-		if (recsize)
-			__kfifo_poke_n(fifo, recsize, n);
-		__kfifo_add_in(fifo, n + recsize);
-	}
-	return ret;
-}
-
-/**
- * kfifo_in_rec - puts some record data into the FIFO
- * @fifo: the fifo to be used.
- * @from: the data to be added.
- * @n: the length of the data to be added.
- * @recsize: size of record field
- *
- * This function copies @n bytes from the @from into the FIFO and returns
- * the number of bytes which cannot be copied.
- * A returned value greater than the @n value means that the record doesn't
- * fit into the buffer.
- *
- * Note that with only one concurrent reader and one concurrent
- * writer, you don't need extra locking to use these functions.
- */
-static inline __must_check unsigned int kfifo_in_rec(struct kfifo *fifo,
-	void *from, unsigned int n, unsigned int recsize)
-{
-	if (!__builtin_constant_p(recsize))
-		return __kfifo_in_generic(fifo, from, n, recsize);
-	return __kfifo_in_rec(fifo, from, n, recsize);
-}
-
-/*
- * __kfifo_out_... internal functions for get date from the fifo
- * do not call it directly, use kfifo_out_rec() instead
- */
-extern unsigned int __kfifo_out_n(struct kfifo *fifo,
-	void *to, unsigned int reclen, unsigned int recsize);
-
-extern unsigned int __kfifo_out_generic(struct kfifo *fifo,
-	void *to, unsigned int n,
-	unsigned int recsize, unsigned int *total);
-
-static inline unsigned int __kfifo_out_rec(struct kfifo *fifo,
-	void *to, unsigned int n, unsigned int recsize,
-	unsigned int *total)
-{
-	unsigned int l;
-
-	if (!recsize) {
-		l = n;
-		if (total)
-			*total = l;
-	} else {
-		l = __kfifo_peek_n(fifo, recsize);
-		if (total)
-			*total = l;
-		if (n < l)
-			return l;
-	}
-
-	return __kfifo_out_n(fifo, to, l, recsize);
-}
-
-/**
- * kfifo_out_rec - gets some record data from the FIFO
- * @fifo: the fifo to be used.
- * @to: where the data must be copied.
- * @n: the size of the destination buffer.
- * @recsize: size of record field
- * @total: pointer where the total number of to copied bytes should stored
- *
- * This function copies at most @n bytes from the FIFO to @to and returns the
- * number of bytes which cannot be copied.
- * A returned value greater than the @n value means that the record doesn't
- * fit into the @to buffer.
- *
- * Note that with only one concurrent reader and one concurrent
- * writer, you don't need extra locking to use these functions.
- */
-static inline __must_check unsigned int kfifo_out_rec(struct kfifo *fifo,
-	void *to, unsigned int n, unsigned int recsize,
-	unsigned int *total)
-
-{
-	if (!__builtin_constant_p(recsize))
-		return __kfifo_out_generic(fifo, to, n, recsize, total);
-	return __kfifo_out_rec(fifo, to, n, recsize, total);
-}
-
-/*
- * __kfifo_from_user_... internal functions for transfer from user space into
- * the fifo. do not call it directly, use kfifo_from_user_rec() instead
- */
-extern unsigned int __kfifo_from_user_n(struct kfifo *fifo,
-	const void __user *from, unsigned int n, unsigned int recsize);
-
-extern unsigned int __kfifo_from_user_generic(struct kfifo *fifo,
-	const void __user *from, unsigned int n, unsigned int recsize);
-
-static inline unsigned int __kfifo_from_user_rec(struct kfifo *fifo,
-	const void __user *from, unsigned int n, unsigned int recsize)
-{
-	unsigned int ret;
-
-	ret = __kfifo_from_user_n(fifo, from, n, recsize);
-
-	if (likely(ret == 0)) {
-		if (recsize)
-			__kfifo_poke_n(fifo, recsize, n);
-		__kfifo_add_in(fifo, n + recsize);
-	}
-	return ret;
-}
-
-/**
- * kfifo_from_user_rec - puts some data from user space into the FIFO
- * @fifo: the fifo to be used.
- * @from: pointer to the data to be added.
- * @n: the length of the data to be added.
- * @recsize: size of record field
- *
- * This function copies @n bytes from the @from into the
- * FIFO and returns the number of bytes which cannot be copied.
- *
- * If the returned value is equal or less the @n value, the copy_from_user()
- * functions has failed. Otherwise the record doesn't fit into the buffer.
- *
- * Note that with only one concurrent reader and one concurrent
- * writer, you don't need extra locking to use these functions.
- */
-static inline __must_check unsigned int kfifo_from_user_rec(struct kfifo *fifo,
-	const void __user *from, unsigned int n, unsigned int recsize)
-{
-	if (!__builtin_constant_p(recsize))
-		return __kfifo_from_user_generic(fifo, from, n, recsize);
-	return __kfifo_from_user_rec(fifo, from, n, recsize);
-}
-
-/*
- * __kfifo_to_user_... internal functions for transfer fifo data into user space
- * do not call it directly, use kfifo_to_user_rec() instead
- */
-extern unsigned int __kfifo_to_user_n(struct kfifo *fifo,
-	void __user *to, unsigned int n, unsigned int reclen,
-	unsigned int recsize);
-
-extern unsigned int __kfifo_to_user_generic(struct kfifo *fifo,
-	void __user *to, unsigned int n, unsigned int recsize,
-	unsigned int *total);
-
-static inline unsigned int __kfifo_to_user_rec(struct kfifo *fifo,
-	void __user *to, unsigned int n,
-	unsigned int recsize, unsigned int *total)
-{
-	unsigned int l;
-
-	if (!recsize) {
-		l = n;
-		if (total)
-			*total = l;
-	} else {
-		l = __kfifo_peek_n(fifo, recsize);
-		if (total)
-			*total = l;
-		if (n < l)
-			return l;
-	}
-
-	return __kfifo_to_user_n(fifo, to, n, l, recsize);
-}
-
-/**
- * kfifo_to_user_rec - gets data from the FIFO and write it to user space
- * @fifo: the fifo to be used.
- * @to: where the data must be copied.
- * @n: the size of the destination buffer.
- * @recsize: size of record field
- * @total: pointer where the total number of to copied bytes should stored
- *
- * This function copies at most @n bytes from the FIFO to the @to.
- * In case of an error, the function returns the number of bytes which cannot
- * be copied.
- * If the returned value is equal or less the @n value, the copy_to_user()
- * functions has failed. Otherwise the record doesn't fit into the @to buffer.
- *
- * Note that with only one concurrent reader and one concurrent
- * writer, you don't need extra locking to use these functions.
- */
-static inline __must_check unsigned int kfifo_to_user_rec(struct kfifo *fifo,
-		void __user *to, unsigned int n, unsigned int recsize,
-		unsigned int *total)
-{
-	if (!__builtin_constant_p(recsize))
-		return __kfifo_to_user_generic(fifo, to, n, recsize, total);
-	return __kfifo_to_user_rec(fifo, to, n, recsize, total);
-}
-
-/*
- * __kfifo_peek_... internal functions for peek into the next fifo record
- * do not call it directly, use kfifo_peek_rec() instead
- */
-extern unsigned int __kfifo_peek_generic(struct kfifo *fifo,
-				unsigned int recsize);
-
-/**
- * kfifo_peek_rec - gets the size of the next FIFO record data
- * @fifo: the fifo to be used.
- * @recsize: size of record field
- *
- * This function returns the size of the next FIFO record in number of bytes
- */
-static inline __must_check unsigned int kfifo_peek_rec(struct kfifo *fifo,
-	unsigned int recsize)
-{
-	if (!__builtin_constant_p(recsize))
-		return __kfifo_peek_generic(fifo, recsize);
-	if (!recsize)
-		return kfifo_len(fifo);
-	return __kfifo_peek_n(fifo, recsize);
-}
-
-/*
- * __kfifo_skip_... internal functions for skip the next fifo record
- * do not call it directly, use kfifo_skip_rec() instead
- */
-extern void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize);
-
-static inline void __kfifo_skip_rec(struct kfifo *fifo,
-	unsigned int recsize)
-{
-	unsigned int l;
-
-	if (recsize) {
-		l = __kfifo_peek_n(fifo, recsize);
-
-		if (l + recsize <= kfifo_len(fifo)) {
-			__kfifo_add_out(fifo, l + recsize);
-			return;
-		}
-	}
-	kfifo_reset_out(fifo);
-}
-
-/**
- * kfifo_skip_rec - skip the next fifo out record
- * @fifo: the fifo to be used.
- * @recsize: size of record field
- *
- * This function skips the next FIFO record
- */
-static inline void kfifo_skip_rec(struct kfifo *fifo,
-	unsigned int recsize)
-{
-	if (!__builtin_constant_p(recsize))
-		__kfifo_skip_generic(fifo, recsize);
-	else
-		__kfifo_skip_rec(fifo, recsize);
-}
-
-/**
- * kfifo_avail_rec - returns the number of bytes available in a record FIFO
- * @fifo: the fifo to be used.
- * @recsize: size of record field
- */
-static inline __must_check unsigned int kfifo_avail_rec(struct kfifo *fifo,
-	unsigned int recsize)
-{
-	unsigned int l = kfifo_size(fifo) - kfifo_len(fifo);
-
-	return (l > recsize) ? l - recsize : 0;
-}
-
-#endif
+/*
+ * A generic kernel FIFO implementation
+ *
+ * Copyright (C) 2009/2010 Stefani Seibold <stefani@...bold.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.
+ *
+ */
+
+#ifndef _LINUX_KFIFO_H
+#define _LINUX_KFIFO_H
+
+/*
+ * How to porting drivers to the new generic FIFO API:
+ *
+ * - Modify the declaration of the "struct kfifo *" object into a
+ *   in-place "struct kfifo" object
+ * - Init the in-place object with kfifo_alloc() or kfifo_init()
+ *   Note: The address of the in-place "struct kfifo" object must be
+ *   passed as the first argument to this functions
+ * - Replace the use of __kfifo_put into kfifo_in and __kfifo_get
+ *   into kfifo_out
+ * - Replace the use of kfifo_put into kfifo_in_spinlocked and kfifo_get
+ *   into kfifo_out_spinlocked
+ *   Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc
+ *   must be passed now to the kfifo_in_spinlocked and kfifo_out_spinlocked
+ *   as the last parameter
+ * - The formerly __kfifo_* functions are renamed into kfifo_*
+ */
+
+/*
+ * Note about locking : There is no locking required until only * one reader
+ * and one writer is using the fifo and no kfifo_reset() will be * called
+ *  kfifo_reset_out() can be safely used, until it will be only called
+ * in the reader thread.
+ *  For multiple writer and one reader there is only a need to lock the writer.
+ * And vice versa for only one writer and multiple reader there is only a need
+ * to lock the reader.
+ */
+
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/stddef.h>
+#include <linux/scatterlist.h>
+
+struct __kfifo {
+	unsigned int	in;
+	unsigned int	out;
+	unsigned int	mask;
+	unsigned int	esize;
+	void		*data;
+};
+
+#define __STRUCT_KFIFO_COMMON(datatype, recsize, ptrtype) \
+	union { \
+		struct __kfifo	kfifo; \
+		datatype	*type; \
+		char		(*rectype)[recsize]; \
+		ptrtype		*ptr; \
+		const ptrtype	*ptr_const; \
+	}
+
+#define __STRUCT_KFIFO(type, size, recsize, ptrtype) \
+{ \
+	__STRUCT_KFIFO_COMMON(type, recsize, ptrtype); \
+	type		buf[((size < 2) || (size & (size - 1))) ? -1 : size]; \
+}
+
+#define STRUCT_KFIFO(type, size) \
+	struct __STRUCT_KFIFO(type, size, 0, type)
+
+#define __STRUCT_KFIFO_PTR(type, recsize, ptrtype) \
+{ \
+	__STRUCT_KFIFO_COMMON(type, recsize, ptrtype); \
+	type		buf[0]; \
+}
+
+#define STRUCT_KFIFO_PTR(type) \
+	struct __STRUCT_KFIFO_PTR(type, 0, type)
+
+/*
+ * define compatibility "struct kfifo" for dynamic allocated fifos
+ */
+struct kfifo __STRUCT_KFIFO_PTR(unsigned char, 0, void);
+
+#define STRUCT_KFIFO_REC_1(size) \
+	struct __STRUCT_KFIFO(unsigned char, size, 1, void)
+
+#define STRUCT_KFIFO_REC_2(size) \
+	struct __STRUCT_KFIFO(unsigned char, size, 2, void)
+
+/*
+ * define kfifo_rec types
+ */
+struct kfifo_rec_ptr_1 __STRUCT_KFIFO_PTR(unsigned char, 1, void);
+struct kfifo_rec_ptr_2 __STRUCT_KFIFO_PTR(unsigned char, 2, void);
+
+/*
+ * helper macro to distinguish between real in place fifo where the fifo
+ * array is a part of the structure and the fifo type where the array is
+ * outside of the fifo structure.
+ */
+#define	__is_kfifo_ptr(fifo)	(sizeof(*fifo) == sizeof(struct __kfifo))
+
+/**
+ * DECLARE_KFIFO_PTR - macro to declare a fifo pointer object
+ * @fifo: name of the declared fifo
+ * @type: type of the fifo elements
+ */
+#define DECLARE_KFIFO_PTR(fifo, type)	STRUCT_KFIFO_PTR(type) fifo
+
+/**
+ * DECLARE_KFIFO - macro to declare a fifo object
+ * @fifo: name of the declared fifo
+ * @type: type of the fifo elements
+ * @size: the number of elements in the fifo, this must be a power of 2
+ */
+#define DECLARE_KFIFO(fifo, type, size)	STRUCT_KFIFO(type, size) fifo
+
+/**
+ * INIT_KFIFO - Initialize a fifo declared by DECLARE_KFIFO
+ * @fifo: name of the declared fifo datatype
+ */
+#define INIT_KFIFO(fifo) \
+(void)({ \
+	typeof(&(fifo)) __tmp = &(fifo); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	__kfifo->in = 0; \
+	__kfifo->out = 0; \
+	__kfifo->mask = __is_kfifo_ptr(__tmp) ? 0 : ARRAY_SIZE(__tmp->buf) - 1;\
+	__kfifo->esize = sizeof(*__tmp->buf); \
+	__kfifo->data = __is_kfifo_ptr(__tmp) ?  NULL : __tmp->buf; \
+})
+
+/**
+ * DEFINE_KFIFO - macro to define and initialize a fifo
+ * @fifo: name of the declared fifo datatype
+ * @type: type of the fifo elements
+ * @size: the number of elements in the fifo, this must be a power of 2
+ *
+ * Note: the macro can be used for global and local fifo data type variables.
+ */
+#define DEFINE_KFIFO(fifo, type, size) \
+	DECLARE_KFIFO(fifo, type, size) = \
+	(typeof(fifo)) { \
+		{ \
+			{ \
+			.in	= 0, \
+			.out	= 0, \
+			.mask	= __is_kfifo_ptr(&(fifo)) ? \
+				  0 : \
+				  ARRAY_SIZE((fifo).buf) - 1, \
+			.esize	= sizeof(*(fifo).buf), \
+			.data	= __is_kfifo_ptr(&(fifo)) ? \
+				NULL : \
+				(fifo).buf, \
+			} \
+		} \
+	}
+
+
+static inline unsigned int __must_check
+__kfifo_must_check_helper(unsigned int val)
+{
+	return val;
+}
+
+/**
+ * kfifo_initialized - Check if the fifo is initialized
+ * @fifo: address of the fifo to check
+ *
+ * Return %true if fifo is initialized, otherwise %false.
+ * Assumes the fifo was 0 before.
+ */
+#define kfifo_initialized(fifo) ((fifo)->kfifo.mask)
+
+/**
+ * kfifo_esize - returns the size of the element managed by the fifo
+ * @fifo: address of the fifo to be used
+ */
+#define kfifo_esize(fifo)	((fifo)->kfifo.esize)
+
+/**
+ * kfifo_recsize - returns the size of the record length field
+ * @fifo: address of the fifo to be used
+ */
+#define kfifo_recsize(fifo)	(sizeof(*(fifo)->rectype))
+
+/**
+ * kfifo_size - returns the size of the fifo in elements
+ * @fifo: address of the fifo to be used
+ */
+#define kfifo_size(fifo)	((fifo)->kfifo.mask + 1)
+
+/**
+ * kfifo_reset - removes the entire fifo content
+ * @fifo: address of the fifo to be used
+ *
+ * Note: usage of kfifo_reset() is dangerous. It should be only called when the
+ * fifo is exclusived locked or when it is secured that no other thread is
+ * accessing the fifo.
+ */
+#define kfifo_reset(fifo) \
+(void)({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	__tmp->kfifo.in = __tmp->kfifo.out = 0; \
+})
+
+/**
+ * kfifo_reset_out - skip fifo content
+ * @fifo: address of the fifo to be used
+ *
+ * Note: The usage of kfifo_reset_out() is safe until it will be only called
+ * from the reader thread and there is only one concurrent reader. Otherwise
+ * it is dangerous and must be handled in the same way as kfifo_reset().
+ */
+#define kfifo_reset_out(fifo)	\
+(void)({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	__tmp->kfifo.out = __tmp->kfifo.in; \
+})
+
+/**
+ * kfifo_len - returns the number of used elements in the fifo
+ * @fifo: address of the fifo to be used
+ */
+#define kfifo_len(fifo) \
+({ \
+	typeof(fifo + 1) __tmpl = (fifo); \
+	__tmpl->kfifo.in - __tmpl->kfifo.out; \
+})
+
+/**
+ * kfifo_is_empty - returns true if the fifo is empty
+ * @fifo: address of the fifo to be used
+ */
+#define	kfifo_is_empty(fifo) \
+({ \
+	typeof(fifo + 1) __tmpq = (fifo); \
+	__tmpq->kfifo.in == __tmpq->kfifo.out; \
+})
+
+/**
+ * kfifo_is_full - returns true if the fifo is full
+ * @fifo: address of the fifo to be used
+ */
+#define	kfifo_is_full(fifo) \
+({ \
+	typeof(fifo + 1) __tmpq = (fifo); \
+	kfifo_len(__tmpq) > __tmpq->kfifo.mask; \
+})
+
+/**
+ * kfifo_avail - returns the number of unused elements in the fifo
+ * @fifo: address of the fifo to be used
+ */
+#define	kfifo_avail(fifo) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmpq = (fifo); \
+	const size_t __recsize = sizeof(*__tmpq->rectype); \
+	unsigned int __avail = kfifo_size(__tmpq) - kfifo_len(__tmpq); \
+	(__recsize) ? ((__avail <= __recsize) ? 0 : \
+	__kfifo_max_r(__avail - __recsize, __recsize)) : \
+	__avail; \
+}) \
+)
+
+/**
+ * kfifo_skip - skip output data
+ * @fifo: address of the fifo to be used
+ */
+#define	kfifo_skip(fifo) \
+(void)({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (__recsize) \
+		__kfifo_skip_r(__kfifo, __recsize); \
+	else \
+		__kfifo->out++; \
+})
+
+/**
+ * kfifo_peek_len - gets the size of the next fifo record
+ * @fifo: address of the fifo to be used
+ *
+ * This function returns the size of the next fifo record in number of bytes.
+ */
+#define kfifo_peek_len(fifo) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(!__recsize) ? kfifo_len(__tmp) * sizeof(*__tmp->type) : \
+	__kfifo_len_r(__kfifo, __recsize); \
+}) \
+)
+
+/**
+ * kfifo_alloc - dynamically allocates a new fifo buffer
+ * @fifo: pointer to the fifo
+ * @size: the number of elements in the fifo, this must be a power of 2
+ * @gfp_mask: get_free_pages mask, passed to kmalloc()
+ *
+ * This macro dynamically allocates a new fifo buffer.
+ *
+ * The numer of elements will be rounded-up to a power of 2.
+ * The fifo will be release with kfifo_free().
+ * Return 0 if no error, otherwise an error code.
+ */
+#define kfifo_alloc(fifo, size, gfp_mask) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	__is_kfifo_ptr(__tmp) ? \
+	__kfifo_alloc(__kfifo, size, sizeof(*__tmp->type), gfp_mask) : \
+	-EINVAL; \
+}) \
+)
+
+/**
+ * kfifo_free - frees the fifo
+ * @fifo: the fifo to be freed
+ */
+#define kfifo_free(fifo) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (__is_kfifo_ptr(__tmp)) \
+		__kfifo_free(__kfifo); \
+})
+
+/**
+ * kfifo_init - initialize a fifo using a preallocated buffer
+ * @fifo: the fifo to assign the buffer
+ * @buffer: the preallocated buffer to be used
+ * @size: the size of the internal buffer, this have to be a power of 2
+ *
+ * This macro initialize a fifo using a preallocated buffer.
+ *
+ * The numer of elements will be rounded-up to a power of 2.
+ * Return 0 if no error, otherwise an error code.
+ */
+#define kfifo_init(fifo, buffer, size) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	__is_kfifo_ptr(__tmp) ? \
+	__kfifo_init(__kfifo, buffer, size, sizeof(*__tmp->type)) : \
+	-EINVAL; \
+})
+
+/**
+ * kfifo_put - put data into the fifo
+ * @fifo: address of the fifo to be used
+ * @val: the data to be added
+ *
+ * This macro copies the given value into the fifo.
+ * It returns 0 if the fifo was full. Otherwise it returns the number
+ * processed elements.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_put(fifo, val) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(val + 1) __val = (val); \
+	unsigned int __ret; \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) { \
+		typeof(__tmp->ptr_const) __dummy __attribute__ ((unused)); \
+		__dummy = (typeof(__val))NULL; \
+	} \
+	if (__recsize) \
+		__ret = __kfifo_in_r(__kfifo, __val, sizeof(*__val), \
+			__recsize); \
+	else { \
+		__ret = !kfifo_is_full(__tmp); \
+		if (__ret) { \
+			(__is_kfifo_ptr(__tmp) ? \
+			((typeof(__tmp->type))__kfifo->data) : \
+			(__tmp->buf) \
+			)[__kfifo->in & __tmp->kfifo.mask] = \
+				*(typeof(__tmp->type))__val; \
+			smp_wmb(); \
+			__kfifo->in++; \
+		} \
+	} \
+	__ret; \
+})
+
+/**
+ * kfifo_get - get data from the fifo
+ * @fifo: address of the fifo to be used
+ * @val: the var where to store the data to be added
+ *
+ * This macro reads the data from the fifo.
+ * It returns 0 if the fifo was empty. Otherwise it returns the number
+ * processed elements.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_get(fifo, val) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(val + 1) __val = (val); \
+	unsigned int __ret; \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) \
+		__val = (typeof(__tmp->ptr))0; \
+	if (__recsize) \
+		__ret = __kfifo_out_r(__kfifo, __val, sizeof(*__val), \
+			__recsize); \
+	else { \
+		__ret = !kfifo_is_empty(__tmp); \
+		if (__ret) { \
+			*(typeof(__tmp->type))__val = \
+				(__is_kfifo_ptr(__tmp) ? \
+				((typeof(__tmp->type))__kfifo->data) : \
+				(__tmp->buf) \
+				)[__kfifo->out & __tmp->kfifo.mask]; \
+			smp_wmb(); \
+			__kfifo->out++; \
+		} \
+	} \
+	__ret; \
+}) \
+)
+
+/**
+ * kfifo_peek - get data from the fifo without removing
+ * @fifo: address of the fifo to be used
+ * @val: the var where to store the data to be added
+ *
+ * This reads the data from the fifo without removing it from the fifo.
+ * It returns 0 if the fifo was empty. Otherwise it returns the number
+ * processed elements.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_peek(fifo, val) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(val + 1) __val = (val); \
+	unsigned int __ret; \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) \
+		__val = (typeof(__tmp->ptr))NULL; \
+	if (__recsize) \
+		__ret = __kfifo_out_peek_r(__kfifo, __val, sizeof(*__val), \
+			__recsize); \
+	else { \
+		__ret = !kfifo_is_empty(__tmp); \
+		if (__ret) { \
+			*(typeof(__tmp->type))__val = \
+				(__is_kfifo_ptr(__tmp) ? \
+				((typeof(__tmp->type))__kfifo->data) : \
+				(__tmp->buf) \
+				)[__kfifo->out & __tmp->kfifo.mask]; \
+			smp_wmb(); \
+		} \
+	} \
+	__ret; \
+}) \
+)
+
+/**
+ * kfifo_in - put data into the fifo
+ * @fifo: address of the fifo to be used
+ * @buf: the data to be added
+ * @n: number of elements to be added
+ *
+ * This macro copies the given buffer into the fifo and returns the
+ * number of copied elements.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_in(fifo, buf, n) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(buf + 1) __buf = (buf); \
+	unsigned long __n = (n); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) { \
+		typeof(__tmp->ptr_const) __dummy __attribute__ ((unused)); \
+		__dummy = (typeof(__buf))NULL; \
+	} \
+	(__recsize) ?\
+	__kfifo_in_r(__kfifo, __buf, __n, __recsize) : \
+	__kfifo_in(__kfifo, __buf, __n); \
+})
+
+/**
+ * kfifo_in_spinlocked - put data into the fifo using a spinlock for locking
+ * @fifo: address of the fifo to be used
+ * @buf: the data to be added
+ * @n: number of elements to be added
+ * @lock: pointer to the spinlock to use for locking
+ *
+ * This macro copies the given values buffer into the fifo and returns the
+ * number of copied elements.
+ */
+#define	kfifo_in_spinlocked(fifo, buf, n, lock) \
+({ \
+	unsigned long __flags; \
+	unsigned int __ret; \
+	spin_lock_irqsave(lock, __flags); \
+	__ret = kfifo_in(fifo, buf, n); \
+	spin_unlock_irqrestore(lock, __flags); \
+	__ret; \
+})
+
+/* alias for kfifo_in_spinlocked, will be removed in a future release */
+#define kfifo_in_locked(fifo, buf, n, lock) \
+		kfifo_in_spinlocked(fifo, buf, n, lock)
+
+/**
+ * kfifo_out - get data from the fifo
+ * @fifo: address of the fifo to be used
+ * @buf: pointer to the storage buffer
+ * @n: max. number of elements to get
+ *
+ * This macro get some data from the fifo and return the numbers of elements
+ * copied.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_out(fifo, buf, n) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(buf + 1) __buf = (buf); \
+	unsigned long __n = (n); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) { \
+		typeof(__tmp->ptr) __dummy = NULL; \
+		__buf = __dummy; \
+	} \
+	(__recsize) ?\
+	__kfifo_out_r(__kfifo, __buf, __n, __recsize) : \
+	__kfifo_out(__kfifo, __buf, __n); \
+}) \
+)
+
+/**
+ * kfifo_out_spinlocked - get data from the fifo using a spinlock for locking
+ * @fifo: address of the fifo to be used
+ * @buf: pointer to the storage buffer
+ * @n: max. number of elements to get
+ * @lock: pointer to the spinlock to use for locking
+ *
+ * This macro get the data from the fifo and return the numbers of elements
+ * copied.
+ */
+#define	kfifo_out_spinlocked(fifo, buf, n, lock) \
+__kfifo_must_check_helper( \
+({ \
+	unsigned long __flags; \
+	unsigned int __ret; \
+	spin_lock_irqsave(lock, __flags); \
+	__ret = kfifo_out(fifo, buf, n); \
+	spin_unlock_irqrestore(lock, __flags); \
+	__ret; \
+}) \
+)
+
+/* alias for kfifo_out_spinlocked, will be removed in a future release */
+#define kfifo_out_locked(fifo, buf, n, lock) \
+		kfifo_out_spinlocked(fifo, buf, n, lock)
+
+/**
+ * kfifo_from_user - puts some data from user space into the fifo
+ * @fifo: address of the fifo to be used
+ * @from: pointer to the data to be added
+ * @len: the length of the data to be added
+ * @copied: pointer to output variable to store the number of copied bytes
+ *
+ * This macro copies at most @len bytes from the @from into the
+ * fifo, depending of the available space and returns -EFAULT/0.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_from_user(fifo, from, len, copied) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	const void __user *__from = (from); \
+	unsigned int __len = (len); \
+	unsigned int *__copied = (copied); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(__recsize) ? \
+	__kfifo_from_user_r(__kfifo, __from, __len,  __copied, __recsize) : \
+	__kfifo_from_user(__kfifo, __from, __len, __copied); \
+}) \
+)
+
+/**
+ * kfifo_to_user - copies data from the fifo into user space
+ * @fifo: address of the fifo to be used
+ * @to: where the data must be copied
+ * @len: the size of the destination buffer
+ * @copied: pointer to output variable to store the number of copied bytes
+ *
+ * This macro copies at most @len bytes from the fifo into the
+ * @to buffer and returns -EFAULT/0.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_to_user(fifo, to, len, copied) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	void __user *__to = (to); \
+	unsigned int __len = (len); \
+	unsigned int *__copied = (copied); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(__recsize) ? \
+	__kfifo_to_user_r(__kfifo, __to, __len, __copied, __recsize) : \
+	__kfifo_to_user(__kfifo, __to, __len, __copied); \
+}) \
+)
+
+/**
+ * kfifo_dma_in_prepare - setup a scatterlist for DMA input
+ * @fifo: address of the fifo to be used
+ * @sgl: pointer to the scatterlist array
+ * @nents: number of entries in the scatterlist array
+ * @len: number of elements to transfer
+ *
+ * This macro fills a scatterlist for DMA input.
+ * It returns the number entries in the scatterlist array.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macros.
+ */
+#define	kfifo_dma_in_prepare(fifo, sgl, nents, len) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	struct scatterlist *__sgl = (sgl); \
+	int __nents = (nents); \
+	unsigned int __len = (len); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(__recsize) ? \
+	__kfifo_dma_in_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) : \
+	__kfifo_dma_in_prepare(__kfifo, __sgl, __nents, __len); \
+})
+
+/**
+ * kfifo_dma_in_finish - finish a DMA IN operation
+ * @fifo: address of the fifo to be used
+ * @len: number of bytes to received
+ *
+ * This macro finish a DMA IN operation. The in counter will be updated by
+ * the len parameter. No error checking will be done.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macros.
+ */
+#define kfifo_dma_in_finish(fifo, len) \
+(void)({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	unsigned int __len = (len); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (__recsize) \
+		__kfifo_dma_in_finish_r(__kfifo, __len, __recsize); \
+	else \
+		__kfifo->in += __len / sizeof(*__tmp->type); \
+})
+
+/**
+ * kfifo_dma_out_prepare - setup a scatterlist for DMA output
+ * @fifo: address of the fifo to be used
+ * @sgl: pointer to the scatterlist array
+ * @nents: number of entries in the scatterlist array
+ * @len: number of elements to transfer
+ *
+ * This macro fills a scatterlist for DMA output which at most @len bytes
+ * to transfer.
+ * It returns the number entries in the scatterlist array.
+ * A zero means there is no space available and the scatterlist is not filled.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macros.
+ */
+#define	kfifo_dma_out_prepare(fifo, sgl, nents, len) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	struct scatterlist *__sgl = (sgl); \
+	int __nents = (nents); \
+	unsigned int __len = (len); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(__recsize) ? \
+	__kfifo_dma_out_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) : \
+	__kfifo_dma_out_prepare(__kfifo, __sgl, __nents, __len); \
+})
+
+/**
+ * kfifo_dma_out_finish - finish a DMA OUT operation
+ * @fifo: address of the fifo to be used
+ * @len: number of bytes transferd
+ *
+ * This macro finish a DMA OUT operation. The out counter will be updated by
+ * the len parameter. No error checking will be done.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macros.
+ */
+#define kfifo_dma_out_finish(fifo, len) \
+(void)({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	unsigned int __len = (len); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (__recsize) \
+		__kfifo_dma_out_finish_r(__kfifo, __recsize); \
+	else \
+		__kfifo->out += __len / sizeof(*__tmp->type); \
+})
+
+/**
+ * kfifo_out_peek - gets some data from the fifo
+ * @fifo: address of the fifo to be used
+ * @buf: pointer to the storage buffer
+ * @n: max. number of elements to get
+ *
+ * This macro get the data from the fifo and return the numbers of elements
+ * copied. The data is not removed from the fifo.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_out_peek(fifo, buf, n) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(buf + 1) __buf = (buf); \
+	unsigned long __n = (n); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) { \
+		typeof(__tmp->ptr) __dummy __attribute__ ((unused)) = NULL; \
+		__buf = __dummy; \
+	} \
+	(__recsize) ? \
+	__kfifo_out_peek_r(__kfifo, __buf, __n, __recsize) : \
+	__kfifo_out_peek(__kfifo, __buf, __n); \
+}) \
+)
+
+extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
+	size_t esize, gfp_t gfp_mask);
+
+extern void __kfifo_free(struct __kfifo *fifo);
+
+extern int __kfifo_init(struct __kfifo *fifo, void *buffer,
+	unsigned int size, size_t esize);
+
+extern unsigned int __kfifo_in(struct __kfifo *fifo,
+	const void *buf, unsigned int len);
+
+extern unsigned int __kfifo_out(struct __kfifo *fifo,
+	void *buf, unsigned int len);
+
+extern int __kfifo_from_user(struct __kfifo *fifo,
+	const void __user *from, unsigned long len, unsigned int *copied);
+
+extern int __kfifo_to_user(struct __kfifo *fifo,
+	void __user *to, unsigned long len, unsigned int *copied);
+
+extern unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
+	struct scatterlist *sgl, int nents, unsigned int len);
+
+extern unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
+	struct scatterlist *sgl, int nents, unsigned int len);
+
+extern unsigned int __kfifo_out_peek(struct __kfifo *fifo,
+	void *buf, unsigned int len);
+
+extern unsigned int __kfifo_in_r(struct __kfifo *fifo,
+	const void *buf, unsigned int len, size_t recsize);
+
+extern unsigned int __kfifo_out_r(struct __kfifo *fifo,
+	void *buf, unsigned int len, size_t recsize);
+
+extern int __kfifo_from_user_r(struct __kfifo *fifo,
+	const void __user *from, unsigned long len, unsigned int *copied,
+	size_t recsize);
+
+extern int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
+	unsigned long len, unsigned int *copied, size_t recsize);
+
+extern unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
+	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize);
+
+extern void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
+	unsigned int len, size_t recsize);
+
+extern unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
+	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize);
+
+extern void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize);
+
+extern unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize);
+
+extern unsigned int __kfifo_out_peek_r(struct __kfifo *fifo,
+	void *buf, unsigned int len, size_t recsize);
+
+extern unsigned int __kfifo_max_r(unsigned int len, size_t recsize);
+
+#endif
diff --git a/kernel/kfifo.c b/kernel/kfifo.c
dissimilarity index 87%
index 35edbe2..4502604 100644
--- a/kernel/kfifo.c
+++ b/kernel/kfifo.c
@@ -1,445 +1,601 @@
-/*
- * A generic kernel FIFO implementation.
- *
- * Copyright (C) 2009 Stefani Seibold <stefani@...bold.net>
- * Copyright (C) 2004 Stelian Pop <stelian@...ies.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/kfifo.h>
-#include <linux/log2.h>
-#include <linux/uaccess.h>
-
-static void _kfifo_init(struct kfifo *fifo, void *buffer,
-		unsigned int size)
-{
-	fifo->buffer = buffer;
-	fifo->size = size;
-
-	kfifo_reset(fifo);
-}
-
-/**
- * kfifo_init - initialize a FIFO using a preallocated buffer
- * @fifo: the fifo to assign the buffer
- * @buffer: the preallocated buffer to be used.
- * @size: the size of the internal buffer, this has to be a power of 2.
- *
- */
-void kfifo_init(struct kfifo *fifo, void *buffer, unsigned int size)
-{
-	/* size must be a power of 2 */
-	BUG_ON(!is_power_of_2(size));
-
-	_kfifo_init(fifo, buffer, size);
-}
-EXPORT_SYMBOL(kfifo_init);
-
-/**
- * kfifo_alloc - allocates a new FIFO internal buffer
- * @fifo: the fifo to assign then new buffer
- * @size: the size of the buffer to be allocated, this have to be a power of 2.
- * @gfp_mask: get_free_pages mask, passed to kmalloc()
- *
- * This function dynamically allocates a new fifo internal buffer
- *
- * The size will be rounded-up to a power of 2.
- * The buffer will be release with kfifo_free().
- * Return 0 if no error, otherwise the an error code
- */
-int kfifo_alloc(struct kfifo *fifo, unsigned int size, gfp_t gfp_mask)
-{
-	unsigned char *buffer;
-
-	/*
-	 * round up to the next power of 2, since our 'let the indices
-	 * wrap' technique works only in this case.
-	 */
-	if (!is_power_of_2(size)) {
-		BUG_ON(size > 0x80000000);
-		size = roundup_pow_of_two(size);
-	}
-
-	buffer = kmalloc(size, gfp_mask);
-	if (!buffer) {
-		_kfifo_init(fifo, NULL, 0);
-		return -ENOMEM;
-	}
-
-	_kfifo_init(fifo, buffer, size);
-
-	return 0;
-}
-EXPORT_SYMBOL(kfifo_alloc);
-
-/**
- * kfifo_free - frees the FIFO internal buffer
- * @fifo: the fifo to be freed.
- */
-void kfifo_free(struct kfifo *fifo)
-{
-	kfree(fifo->buffer);
-	_kfifo_init(fifo, NULL, 0);
-}
-EXPORT_SYMBOL(kfifo_free);
-
-/**
- * kfifo_skip - skip output data
- * @fifo: the fifo to be used.
- * @len: number of bytes to skip
- */
-void kfifo_skip(struct kfifo *fifo, unsigned int len)
-{
-	if (len < kfifo_len(fifo)) {
-		__kfifo_add_out(fifo, len);
-		return;
-	}
-	kfifo_reset_out(fifo);
-}
-EXPORT_SYMBOL(kfifo_skip);
-
-static inline void __kfifo_in_data(struct kfifo *fifo,
-		const void *from, unsigned int len, unsigned int off)
-{
-	unsigned int l;
-
-	/*
-	 * Ensure that we sample the fifo->out index -before- we
-	 * start putting bytes into the kfifo.
-	 */
-
-	smp_mb();
-
-	off = __kfifo_off(fifo, fifo->in + off);
-
-	/* first put the data starting from fifo->in to buffer end */
-	l = min(len, fifo->size - off);
-	memcpy(fifo->buffer + off, from, l);
-
-	/* then put the rest (if any) at the beginning of the buffer */
-	memcpy(fifo->buffer, from + l, len - l);
-}
-
-static inline void __kfifo_out_data(struct kfifo *fifo,
-		void *to, unsigned int len, unsigned int off)
-{
-	unsigned int l;
-
-	/*
-	 * Ensure that we sample the fifo->in index -before- we
-	 * start removing bytes from the kfifo.
-	 */
-
-	smp_rmb();
-
-	off = __kfifo_off(fifo, fifo->out + off);
-
-	/* first get the data from fifo->out until the end of the buffer */
-	l = min(len, fifo->size - off);
-	memcpy(to, fifo->buffer + off, l);
-
-	/* then get the rest (if any) from the beginning of the buffer */
-	memcpy(to + l, fifo->buffer, len - l);
-}
-
-static inline int __kfifo_from_user_data(struct kfifo *fifo,
-	 const void __user *from, unsigned int len, unsigned int off,
-	 unsigned *lenout)
-{
-	unsigned int l;
-	int ret;
-
-	/*
-	 * Ensure that we sample the fifo->out index -before- we
-	 * start putting bytes into the kfifo.
-	 */
-
-	smp_mb();
-
-	off = __kfifo_off(fifo, fifo->in + off);
-
-	/* first put the data starting from fifo->in to buffer end */
-	l = min(len, fifo->size - off);
-	ret = copy_from_user(fifo->buffer + off, from, l);
-	if (unlikely(ret)) {
-		*lenout = ret;
-		return -EFAULT;
-	}
-	*lenout = l;
-
-	/* then put the rest (if any) at the beginning of the buffer */
-	ret = copy_from_user(fifo->buffer, from + l, len - l);
-	*lenout += ret ? ret : len - l;
-	return ret ? -EFAULT : 0;
-}
-
-static inline int __kfifo_to_user_data(struct kfifo *fifo,
-		void __user *to, unsigned int len, unsigned int off, unsigned *lenout)
-{
-	unsigned int l;
-	int ret;
-
-	/*
-	 * Ensure that we sample the fifo->in index -before- we
-	 * start removing bytes from the kfifo.
-	 */
-
-	smp_rmb();
-
-	off = __kfifo_off(fifo, fifo->out + off);
-
-	/* first get the data from fifo->out until the end of the buffer */
-	l = min(len, fifo->size - off);
-	ret = copy_to_user(to, fifo->buffer + off, l);
-	*lenout = l;
-	if (unlikely(ret)) {
-		*lenout -= ret;
-		return -EFAULT;
-	}
-
-	/* then get the rest (if any) from the beginning of the buffer */
-	len -= l;
-	ret = copy_to_user(to + l, fifo->buffer, len);
-	if (unlikely(ret)) {
-		*lenout += len - ret;
-		return -EFAULT;
-	}
-	*lenout += len;
-	return 0;
-}
-
-unsigned int __kfifo_in_n(struct kfifo *fifo,
-	const void *from, unsigned int len, unsigned int recsize)
-{
-	if (kfifo_avail(fifo) < len + recsize)
-		return len + 1;
-
-	__kfifo_in_data(fifo, from, len, recsize);
-	return 0;
-}
-EXPORT_SYMBOL(__kfifo_in_n);
-
-/**
- * kfifo_in - puts some data into the FIFO
- * @fifo: the fifo to be used.
- * @from: the data to be added.
- * @len: the length of the data to be added.
- *
- * This function copies at most @len bytes from the @from buffer into
- * the FIFO depending on the free space, and returns the number of
- * bytes copied.
- *
- * Note that with only one concurrent reader and one concurrent
- * writer, you don't need extra locking to use these functions.
- */
-unsigned int kfifo_in(struct kfifo *fifo, const void *from,
-				unsigned int len)
-{
-	len = min(kfifo_avail(fifo), len);
-
-	__kfifo_in_data(fifo, from, len, 0);
-	__kfifo_add_in(fifo, len);
-	return len;
-}
-EXPORT_SYMBOL(kfifo_in);
-
-unsigned int __kfifo_in_generic(struct kfifo *fifo,
-	const void *from, unsigned int len, unsigned int recsize)
-{
-	return __kfifo_in_rec(fifo, from, len, recsize);
-}
-EXPORT_SYMBOL(__kfifo_in_generic);
-
-unsigned int __kfifo_out_n(struct kfifo *fifo,
-	void *to, unsigned int len, unsigned int recsize)
-{
-	if (kfifo_len(fifo) < len + recsize)
-		return len;
-
-	__kfifo_out_data(fifo, to, len, recsize);
-	__kfifo_add_out(fifo, len + recsize);
-	return 0;
-}
-EXPORT_SYMBOL(__kfifo_out_n);
-
-/**
- * kfifo_out - gets some data from the FIFO
- * @fifo: the fifo to be used.
- * @to: where the data must be copied.
- * @len: the size of the destination buffer.
- *
- * This function copies at most @len bytes from the FIFO into the
- * @to buffer and returns the number of copied bytes.
- *
- * Note that with only one concurrent reader and one concurrent
- * writer, you don't need extra locking to use these functions.
- */
-unsigned int kfifo_out(struct kfifo *fifo, void *to, unsigned int len)
-{
-	len = min(kfifo_len(fifo), len);
-
-	__kfifo_out_data(fifo, to, len, 0);
-	__kfifo_add_out(fifo, len);
-
-	return len;
-}
-EXPORT_SYMBOL(kfifo_out);
-
-/**
- * kfifo_out_peek - copy some data from the FIFO, but do not remove it
- * @fifo: the fifo to be used.
- * @to: where the data must be copied.
- * @len: the size of the destination buffer.
- * @offset: offset into the fifo
- *
- * This function copies at most @len bytes at @offset from the FIFO
- * into the @to buffer and returns the number of copied bytes.
- * The data is not removed from the FIFO.
- */
-unsigned int kfifo_out_peek(struct kfifo *fifo, void *to, unsigned int len,
-			    unsigned offset)
-{
-	len = min(kfifo_len(fifo), len + offset);
-
-	__kfifo_out_data(fifo, to, len, offset);
-	return len;
-}
-EXPORT_SYMBOL(kfifo_out_peek);
-
-unsigned int __kfifo_out_generic(struct kfifo *fifo,
-	void *to, unsigned int len, unsigned int recsize,
-	unsigned int *total)
-{
-	return __kfifo_out_rec(fifo, to, len, recsize, total);
-}
-EXPORT_SYMBOL(__kfifo_out_generic);
-
-unsigned int __kfifo_from_user_n(struct kfifo *fifo,
-	const void __user *from, unsigned int len, unsigned int recsize)
-{
-	unsigned total;
-
-	if (kfifo_avail(fifo) < len + recsize)
-		return len + 1;
-
-	__kfifo_from_user_data(fifo, from, len, recsize, &total);
-	return total;
-}
-EXPORT_SYMBOL(__kfifo_from_user_n);
-
-/**
- * kfifo_from_user - puts some data from user space into the FIFO
- * @fifo: the fifo to be used.
- * @from: pointer to the data to be added.
- * @len: the length of the data to be added.
- * @total: the actual returned data length.
- *
- * This function copies at most @len bytes from the @from into the
- * FIFO depending and returns -EFAULT/0.
- *
- * Note that with only one concurrent reader and one concurrent
- * writer, you don't need extra locking to use these functions.
- */
-int kfifo_from_user(struct kfifo *fifo,
-        const void __user *from, unsigned int len, unsigned *total)
-{
-	int ret;
-	len = min(kfifo_avail(fifo), len);
-	ret = __kfifo_from_user_data(fifo, from, len, 0, total);
-	if (ret)
-		return ret;
-	__kfifo_add_in(fifo, len);
-	return 0;
-}
-EXPORT_SYMBOL(kfifo_from_user);
-
-unsigned int __kfifo_from_user_generic(struct kfifo *fifo,
-	const void __user *from, unsigned int len, unsigned int recsize)
-{
-	return __kfifo_from_user_rec(fifo, from, len, recsize);
-}
-EXPORT_SYMBOL(__kfifo_from_user_generic);
-
-unsigned int __kfifo_to_user_n(struct kfifo *fifo,
-	void __user *to, unsigned int len, unsigned int reclen,
-	unsigned int recsize)
-{
-	unsigned int ret, total;
-
-	if (kfifo_len(fifo) < reclen + recsize)
-		return len;
-
-	ret = __kfifo_to_user_data(fifo, to, reclen, recsize, &total);
-
-	if (likely(ret == 0))
-		__kfifo_add_out(fifo, reclen + recsize);
-
-	return total;
-}
-EXPORT_SYMBOL(__kfifo_to_user_n);
-
-/**
- * kfifo_to_user - gets data from the FIFO and write it to user space
- * @fifo: the fifo to be used.
- * @to: where the data must be copied.
- * @len: the size of the destination buffer.
- * @lenout: pointer to output variable with copied data
- *
- * This function copies at most @len bytes from the FIFO into the
- * @to buffer and 0 or -EFAULT.
- *
- * Note that with only one concurrent reader and one concurrent
- * writer, you don't need extra locking to use these functions.
- */
-int kfifo_to_user(struct kfifo *fifo,
-	void __user *to, unsigned int len, unsigned *lenout)
-{
-	int ret;
-	len = min(kfifo_len(fifo), len);
-	ret = __kfifo_to_user_data(fifo, to, len, 0, lenout);
-	__kfifo_add_out(fifo, *lenout);
-	return ret;
-}
-EXPORT_SYMBOL(kfifo_to_user);
-
-unsigned int __kfifo_to_user_generic(struct kfifo *fifo,
-	void __user *to, unsigned int len, unsigned int recsize,
-	unsigned int *total)
-{
-	return __kfifo_to_user_rec(fifo, to, len, recsize, total);
-}
-EXPORT_SYMBOL(__kfifo_to_user_generic);
-
-unsigned int __kfifo_peek_generic(struct kfifo *fifo, unsigned int recsize)
-{
-	if (recsize == 0)
-		return kfifo_avail(fifo);
-
-	return __kfifo_peek_n(fifo, recsize);
-}
-EXPORT_SYMBOL(__kfifo_peek_generic);
-
-void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize)
-{
-	__kfifo_skip_rec(fifo, recsize);
-}
-EXPORT_SYMBOL(__kfifo_skip_generic);
-
+/*
+ * A generic kernel FIFO implementation
+ *
+ * Copyright (C) 2009/2010 Stefani Seibold <stefani@...bold.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);
-- 
1.7.2

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