kfifo API type safety
This patch enhances the type safety for the kfifo API. It is now safe
to put const data into a non const FIFO and the API will now generate a
compiler warning when reading from the fifo where the destination
address is pointing to a const variable.
As a side effect the kfifo_put() does now expect the value of an element
instead a pointer to the element. This was suggested Russell King. It
make the handling of the kfifo_put easier since there is no need to
create a helper variable for getting the address of a pointer or to pass
integers of different sizes.
IMHO the API break is okay, since there are currently only six users of
kfifo_put().
The code is also cleaner by kicking out the "if (0)" expressions.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
index 10308c6..552d51e 100644
--- a/include/linux/kfifo.h
+++ b/include/linux/kfifo.h
@@ -1,7 +1,7 @@
/*
* A generic kernel FIFO implementation
*
- * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
+ * Copyright (C) 2013 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
@@ -67,9 +67,10 @@
union { \
struct __kfifo kfifo; \
datatype *type; \
+ const datatype *const_type; \
char (*rectype)[recsize]; \
ptrtype *ptr; \
- const ptrtype *ptr_const; \
+ ptrtype const *ptr_const; \
}
#define __STRUCT_KFIFO(type, size, recsize, ptrtype) \
@@ -386,16 +387,12 @@
#define kfifo_put(fifo, val) \
({ \
typeof((fifo) + 1) __tmp = (fifo); \
- typeof((val) + 1) __val = (val); \
+ typeof(*__tmp->const_type) __val = (val); \
unsigned int __ret; \
- const size_t __recsize = sizeof(*__tmp->rectype); \
+ 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), \
+ __ret = __kfifo_in_r(__kfifo, &__val, sizeof(__val), \
__recsize); \
else { \
__ret = !kfifo_is_full(__tmp); \
@@ -404,7 +401,7 @@
((typeof(__tmp->type))__kfifo->data) : \
(__tmp->buf) \
)[__kfifo->in & __tmp->kfifo.mask] = \
- *(typeof(__tmp->type))__val; \
+ (typeof(*__tmp->type))__val; \
smp_wmb(); \
__kfifo->in++; \
} \
@@ -415,7 +412,7 @@
/**
* 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
+ * @val: address where to store the data
*
* This macro reads the data from the fifo.
* It returns 0 if the fifo was empty. Otherwise it returns the number
@@ -428,12 +425,10 @@
__kfifo_uint_must_check_helper( \
({ \
typeof((fifo) + 1) __tmp = (fifo); \
- typeof((val) + 1) __val = (val); \
+ typeof(__tmp->ptr) __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); \
@@ -456,7 +451,7 @@
/**
* 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
+ * @val: address where to store the data
*
* 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
@@ -469,12 +464,10 @@
__kfifo_uint_must_check_helper( \
({ \
typeof((fifo) + 1) __tmp = (fifo); \
- typeof((val) + 1) __val = (val); \
+ typeof(__tmp->ptr) __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); \
@@ -508,14 +501,10 @@
#define kfifo_in(fifo, buf, n) \
({ \
typeof((fifo) + 1) __tmp = (fifo); \
- typeof((buf) + 1) __buf = (buf); \
+ typeof(__tmp->ptr_const) __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); \
@@ -561,14 +550,10 @@
__kfifo_uint_must_check_helper( \
({ \
typeof((fifo) + 1) __tmp = (fifo); \
- typeof((buf) + 1) __buf = (buf); \
+ typeof(__tmp->ptr) __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); \
@@ -773,14 +758,10 @@
__kfifo_uint_must_check_helper( \
({ \
typeof((fifo) + 1) __tmp = (fifo); \
- typeof((buf) + 1) __buf = (buf); \
+ typeof(__tmp->ptr) __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); \