enhanced reimplemention of the kfifo API

diff -u -N -r -p linux-2.6.33-rc4.orig/include/linux/kfifo.h linux-2.6.33-rc4.dummy/include/linux/kfifo.h
@@ -1,610 +0,0 @@
-/*
- * A generic kernel FIFO implementation.
- *
- * Copyright (C) 2009 Stefani Seibold <[email protected]>
- * Copyright (C) 2004 Stelian Pop <[email protected]>
- *
- * 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
- *
- * 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)
-
-/**
- * DEFINE_KFIFO - macro to define and initialize a kfifo
- * @name: name of the declared kfifo datatype
- * @size: size of the fifo buffer
- *
- * 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)
-
-#undef __kfifo_initializer
-
-extern void kfifo_init(struct kfifo *fifo, unsigned char *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 unsigned char *from, unsigned int len);
-extern __must_check unsigned int kfifo_out(struct kfifo *fifo,
-				unsigned char *to, unsigned int len);
-
-/**
- * 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 @len 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 unsigned char *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 @len 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,
-	unsigned char *to, unsigned int n, spinlock_t *lock)
-{
-	unsigned long flags;
-	unsigned int ret;
-
-	spin_lock_irqsave(lock, flags);
-
-	ret = kfifo_out(fifo, to, n);
-
-	/*
-	 * optimization: if the FIFO is empty, set the indices to 0
-	 * so we don't wrap the next time
-	 */
-	if (kfifo_is_empty(fifo))
-		kfifo_reset(fifo);
-
-	spin_unlock_irqrestore(lock, flags);
-
-	return ret;
-}
-
-extern void kfifo_skip(struct kfifo *fifo, unsigned int len);
-
-extern __must_check unsigned int kfifo_from_user(struct kfifo *fifo,
-	const void __user *from, unsigned int n);
-
-extern __must_check unsigned int kfifo_to_user(struct kfifo *fifo,
-	void __user *to, unsigned int n);
-
-/*
- * __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

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