提交 37bdfbbf 编写于 作者: S Stefani Seibold 提交者: Linus Torvalds

kfifo: add DEFINE_KFIFO and friends, add very tiny functions

Add DECLARE_KFIFO - macro to declare a kfifo and the associated buffer inside a struct
 Add INIT_KFIFO - Initialize a kfifo declared by DECLARED_KFIFO
 Add DEFINE_KFIFO - macro to define and initialize a kfifo as a global or local object
 Add kfifo_size() - returns the size of the fifo in bytes
 Add kfifo_is_empty() - returns true if the fifo is empty
 Add kfifo_is_full() - returns true if the fifo is full
 Add kfifo_avail() - returns the number of bytes available in the FIFO
 Do some code cleanup
Signed-off-by: NStefani Seibold <stefani@seibold.net>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Acked-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 9842c38e
......@@ -51,6 +51,60 @@ struct kfifo {
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
*
* Note: the macro can be used inside struct or union declaration
* Note: 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 DECLARED_KFIFO
* @name: name of the declared kfifo datatype
* @size: size of the fifo buffer
*/
#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
*
* Note: the macro can be used for global and local kfifo data type variables
* Note: 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,
......@@ -70,6 +124,15 @@ static inline void kfifo_reset(struct kfifo *fifo)
fifo->in = fifo->out = 0;
}
/**
* 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.
......@@ -83,6 +146,33 @@ static inline unsigned int kfifo_len(struct kfifo *fifo)
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.
......@@ -133,8 +223,8 @@ static inline __must_check unsigned int kfifo_out_locked(struct kfifo *fifo,
* optimization: if the FIFO is empty, set the indices to 0
* so we don't wrap the next time
*/
if (fifo->in == fifo->out)
fifo->in = fifo->out = 0;
if (kfifo_is_empty(fifo))
kfifo_reset(fifo);
spin_unlock_irqrestore(lock, flags);
......
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