kfifo: add DEFINE_KFIFO and friends, add very tiny functions (37bdfbbf) · Commits · 戴 / test

include/linux/kfifo.h

+92 −2

Original line number	Diff line number	Diff line
		@@ -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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