kfifo: add the new generic kfifo API

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

Signed-off-by: Stefani Seibold <stefani@seibold.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 844 insertions, 0 deletions

diff --git a/include/linux/kfifo-new.h b/include/linux/kfifo-new.h
new file mode 100644
index 000000000000..311f8753d713
--- /dev/null
+++ b/include/linux/kfifo-new.h
@@ -0,0 +1,844 @@
+/*
+ * 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.
+ *
+ */
+
+#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