![Andi Kleen](/assets/img/avatar_default.png)
On my first try using them I missed that the fifos need to be power of two, resulting in a runtime bug. Document that requirement everywhere (and fix one grammar bug) Signed-off-by: Andi Kleen <ak@linux.intel.com> Acked-by: Stefani Seibold <stefani@seibold.net> Cc: Roland Dreier <rdreier@cisco.com> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: Andy Walls <awalls@radix.net> Cc: Vikram Dhillon <dhillonv10@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
617 lines
17 KiB
C
617 lines
17 KiB
C
/*
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* A generic kernel FIFO implementation.
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*
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* Copyright (C) 2009 Stefani Seibold <stefani@seibold.net>
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* Copyright (C) 2004 Stelian Pop <stelian@popies.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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/*
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* Howto porting drivers to the new generic fifo API:
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*
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* - Modify the declaration of the "struct kfifo *" object into a
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* in-place "struct kfifo" object
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* - Init the in-place object with kfifo_alloc() or kfifo_init()
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* Note: The address of the in-place "struct kfifo" object must be
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* passed as the first argument to this functions
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* - Replace the use of __kfifo_put into kfifo_in and __kfifo_get
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* into kfifo_out
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* - Replace the use of kfifo_put into kfifo_in_locked and kfifo_get
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* into kfifo_out_locked
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* Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc
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* must be passed now to the kfifo_in_locked and kfifo_out_locked
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* as the last parameter.
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* - All formerly name __kfifo_* functions has been renamed into kfifo_*
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*/
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#ifndef _LINUX_KFIFO_H
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#define _LINUX_KFIFO_H
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#include <linux/kernel.h>
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#include <linux/spinlock.h>
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struct kfifo {
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unsigned char *buffer; /* the buffer holding the data */
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unsigned int size; /* the size of the allocated buffer */
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unsigned int in; /* data is added at offset (in % size) */
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unsigned int out; /* data is extracted from off. (out % size) */
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};
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/*
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* Macros for declaration and initialization of the kfifo datatype
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*/
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/* helper macro */
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#define __kfifo_initializer(s, b) \
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(struct kfifo) { \
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.size = s, \
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.in = 0, \
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.out = 0, \
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.buffer = b \
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}
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/**
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* DECLARE_KFIFO - macro to declare a kfifo and the associated buffer
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* @name: name of the declared kfifo datatype
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* @size: size of the fifo buffer. Must be a power of two.
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*
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* Note1: the macro can be used inside struct or union declaration
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* Note2: the macro creates two objects:
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* A kfifo object with the given name and a buffer for the kfifo
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* object named name##kfifo_buffer
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*/
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#define DECLARE_KFIFO(name, size) \
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union { \
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struct kfifo name; \
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unsigned char name##kfifo_buffer[size + sizeof(struct kfifo)]; \
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}
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/**
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* INIT_KFIFO - Initialize a kfifo declared by DECLARE_KFIFO
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* @name: name of the declared kfifo datatype
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*/
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#define INIT_KFIFO(name) \
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name = __kfifo_initializer(sizeof(name##kfifo_buffer) - \
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sizeof(struct kfifo), name##kfifo_buffer)
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/**
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* DEFINE_KFIFO - macro to define and initialize a kfifo
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* @name: name of the declared kfifo datatype
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* @size: size of the fifo buffer. Must be a power of two.
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*
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* Note1: the macro can be used for global and local kfifo data type variables
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* Note2: the macro creates two objects:
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* A kfifo object with the given name and a buffer for the kfifo
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* object named name##kfifo_buffer
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*/
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#define DEFINE_KFIFO(name, size) \
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unsigned char name##kfifo_buffer[size]; \
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struct kfifo name = __kfifo_initializer(size, name##kfifo_buffer)
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#undef __kfifo_initializer
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extern void kfifo_init(struct kfifo *fifo, void *buffer,
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unsigned int size);
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extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size,
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gfp_t gfp_mask);
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extern void kfifo_free(struct kfifo *fifo);
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extern unsigned int kfifo_in(struct kfifo *fifo,
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const void *from, unsigned int len);
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extern __must_check unsigned int kfifo_out(struct kfifo *fifo,
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void *to, unsigned int len);
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extern __must_check unsigned int kfifo_out_peek(struct kfifo *fifo,
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void *to, unsigned int len, unsigned offset);
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/**
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* kfifo_initialized - Check if kfifo is initialized.
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* @fifo: fifo to check
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* Return %true if FIFO is initialized, otherwise %false.
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* Assumes the fifo was 0 before.
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*/
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static inline bool kfifo_initialized(struct kfifo *fifo)
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{
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return fifo->buffer != 0;
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}
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/**
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* kfifo_reset - removes the entire FIFO contents
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* @fifo: the fifo to be emptied.
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*/
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static inline void kfifo_reset(struct kfifo *fifo)
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{
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fifo->in = fifo->out = 0;
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}
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/**
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* kfifo_reset_out - skip FIFO contents
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* @fifo: the fifo to be emptied.
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*/
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static inline void kfifo_reset_out(struct kfifo *fifo)
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{
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smp_mb();
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fifo->out = fifo->in;
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}
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/**
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* kfifo_size - returns the size of the fifo in bytes
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* @fifo: the fifo to be used.
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*/
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static inline __must_check unsigned int kfifo_size(struct kfifo *fifo)
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{
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return fifo->size;
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}
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/**
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* kfifo_len - returns the number of used bytes in the FIFO
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* @fifo: the fifo to be used.
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*/
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static inline unsigned int kfifo_len(struct kfifo *fifo)
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{
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register unsigned int out;
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out = fifo->out;
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smp_rmb();
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return fifo->in - out;
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}
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/**
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* kfifo_is_empty - returns true if the fifo is empty
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* @fifo: the fifo to be used.
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*/
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static inline __must_check int kfifo_is_empty(struct kfifo *fifo)
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{
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return fifo->in == fifo->out;
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}
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/**
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* kfifo_is_full - returns true if the fifo is full
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* @fifo: the fifo to be used.
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*/
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static inline __must_check int kfifo_is_full(struct kfifo *fifo)
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{
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return kfifo_len(fifo) == kfifo_size(fifo);
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}
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/**
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* kfifo_avail - returns the number of bytes available in the FIFO
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* @fifo: the fifo to be used.
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*/
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static inline __must_check unsigned int kfifo_avail(struct kfifo *fifo)
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{
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return kfifo_size(fifo) - kfifo_len(fifo);
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}
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/**
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* kfifo_in_locked - puts some data into the FIFO using a spinlock for locking
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* @fifo: the fifo to be used.
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* @from: the data to be added.
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* @n: the length of the data to be added.
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* @lock: pointer to the spinlock to use for locking.
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*
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* This function copies at most @len bytes from the @from buffer into
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* the FIFO depending on the free space, and returns the number of
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* bytes copied.
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*/
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static inline unsigned int kfifo_in_locked(struct kfifo *fifo,
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const void *from, unsigned int n, spinlock_t *lock)
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{
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unsigned long flags;
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unsigned int ret;
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spin_lock_irqsave(lock, flags);
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ret = kfifo_in(fifo, from, n);
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spin_unlock_irqrestore(lock, flags);
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return ret;
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}
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/**
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* kfifo_out_locked - gets some data from the FIFO using a spinlock for locking
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* @fifo: the fifo to be used.
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* @to: where the data must be copied.
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* @n: the size of the destination buffer.
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* @lock: pointer to the spinlock to use for locking.
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*
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* This function copies at most @len bytes from the FIFO into the
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* @to buffer and returns the number of copied bytes.
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*/
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static inline __must_check unsigned int kfifo_out_locked(struct kfifo *fifo,
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void *to, unsigned int n, spinlock_t *lock)
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{
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unsigned long flags;
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unsigned int ret;
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spin_lock_irqsave(lock, flags);
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ret = kfifo_out(fifo, to, n);
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spin_unlock_irqrestore(lock, flags);
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return ret;
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}
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extern void kfifo_skip(struct kfifo *fifo, unsigned int len);
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extern __must_check int kfifo_from_user(struct kfifo *fifo,
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const void __user *from, unsigned int n, unsigned *lenout);
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extern __must_check int kfifo_to_user(struct kfifo *fifo,
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void __user *to, unsigned int n, unsigned *lenout);
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/*
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* __kfifo_add_out internal helper function for updating the out offset
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*/
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static inline void __kfifo_add_out(struct kfifo *fifo,
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unsigned int off)
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{
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smp_mb();
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fifo->out += off;
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}
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/*
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* __kfifo_add_in internal helper function for updating the in offset
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*/
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static inline void __kfifo_add_in(struct kfifo *fifo,
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unsigned int off)
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{
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smp_wmb();
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fifo->in += off;
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}
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/*
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* __kfifo_off internal helper function for calculating the index of a
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* given offeset
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*/
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static inline unsigned int __kfifo_off(struct kfifo *fifo, unsigned int off)
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{
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return off & (fifo->size - 1);
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}
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/*
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* __kfifo_peek_n internal helper function for determinate the length of
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* the next record in the fifo
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*/
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static inline unsigned int __kfifo_peek_n(struct kfifo *fifo,
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unsigned int recsize)
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{
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#define __KFIFO_GET(fifo, off, shift) \
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((fifo)->buffer[__kfifo_off((fifo), (fifo)->out+(off))] << (shift))
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unsigned int l;
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l = __KFIFO_GET(fifo, 0, 0);
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if (--recsize)
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l |= __KFIFO_GET(fifo, 1, 8);
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return l;
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#undef __KFIFO_GET
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}
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/*
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* __kfifo_poke_n internal helper function for storing the length of
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* the next record into the fifo
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*/
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static inline void __kfifo_poke_n(struct kfifo *fifo,
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unsigned int recsize, unsigned int n)
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{
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#define __KFIFO_PUT(fifo, off, val, shift) \
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( \
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(fifo)->buffer[__kfifo_off((fifo), (fifo)->in+(off))] = \
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(unsigned char)((val) >> (shift)) \
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)
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__KFIFO_PUT(fifo, 0, n, 0);
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if (--recsize)
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__KFIFO_PUT(fifo, 1, n, 8);
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#undef __KFIFO_PUT
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}
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/*
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* __kfifo_in_... internal functions for put date into the fifo
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* do not call it directly, use kfifo_in_rec() instead
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*/
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extern unsigned int __kfifo_in_n(struct kfifo *fifo,
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const void *from, unsigned int n, unsigned int recsize);
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extern unsigned int __kfifo_in_generic(struct kfifo *fifo,
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const void *from, unsigned int n, unsigned int recsize);
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static inline unsigned int __kfifo_in_rec(struct kfifo *fifo,
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const void *from, unsigned int n, unsigned int recsize)
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{
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unsigned int ret;
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ret = __kfifo_in_n(fifo, from, n, recsize);
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if (likely(ret == 0)) {
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if (recsize)
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__kfifo_poke_n(fifo, recsize, n);
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__kfifo_add_in(fifo, n + recsize);
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}
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return ret;
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}
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/**
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* kfifo_in_rec - puts some record data into the FIFO
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* @fifo: the fifo to be used.
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* @from: the data to be added.
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* @n: the length of the data to be added.
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* @recsize: size of record field
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*
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* This function copies @n bytes from the @from into the FIFO and returns
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* the number of bytes which cannot be copied.
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* A returned value greater than the @n value means that the record doesn't
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* fit into the buffer.
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*
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* Note that with only one concurrent reader and one concurrent
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* writer, you don't need extra locking to use these functions.
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*/
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static inline __must_check unsigned int kfifo_in_rec(struct kfifo *fifo,
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void *from, unsigned int n, unsigned int recsize)
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{
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if (!__builtin_constant_p(recsize))
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return __kfifo_in_generic(fifo, from, n, recsize);
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return __kfifo_in_rec(fifo, from, n, recsize);
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}
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/*
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* __kfifo_out_... internal functions for get date from the fifo
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* do not call it directly, use kfifo_out_rec() instead
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*/
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extern unsigned int __kfifo_out_n(struct kfifo *fifo,
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void *to, unsigned int reclen, unsigned int recsize);
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extern unsigned int __kfifo_out_generic(struct kfifo *fifo,
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void *to, unsigned int n,
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unsigned int recsize, unsigned int *total);
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static inline unsigned int __kfifo_out_rec(struct kfifo *fifo,
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void *to, unsigned int n, unsigned int recsize,
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unsigned int *total)
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{
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unsigned int l;
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if (!recsize) {
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l = n;
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if (total)
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*total = l;
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} else {
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l = __kfifo_peek_n(fifo, recsize);
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if (total)
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*total = l;
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if (n < l)
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return l;
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}
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return __kfifo_out_n(fifo, to, l, recsize);
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}
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/**
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* kfifo_out_rec - gets some record data from the FIFO
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* @fifo: the fifo to be used.
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* @to: where the data must be copied.
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* @n: the size of the destination buffer.
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* @recsize: size of record field
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* @total: pointer where the total number of to copied bytes should stored
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*
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* This function copies at most @n bytes from the FIFO to @to and returns the
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* number of bytes which cannot be copied.
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* A returned value greater than the @n value means that the record doesn't
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* fit into the @to buffer.
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*
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* Note that with only one concurrent reader and one concurrent
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* writer, you don't need extra locking to use these functions.
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*/
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static inline __must_check unsigned int kfifo_out_rec(struct kfifo *fifo,
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void *to, unsigned int n, unsigned int recsize,
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unsigned int *total)
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{
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if (!__builtin_constant_p(recsize))
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return __kfifo_out_generic(fifo, to, n, recsize, total);
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return __kfifo_out_rec(fifo, to, n, recsize, total);
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}
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/*
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* __kfifo_from_user_... internal functions for transfer from user space into
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* the fifo. do not call it directly, use kfifo_from_user_rec() instead
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*/
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extern unsigned int __kfifo_from_user_n(struct kfifo *fifo,
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const void __user *from, unsigned int n, unsigned int recsize);
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extern unsigned int __kfifo_from_user_generic(struct kfifo *fifo,
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const void __user *from, unsigned int n, unsigned int recsize);
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static inline unsigned int __kfifo_from_user_rec(struct kfifo *fifo,
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const void __user *from, unsigned int n, unsigned int recsize)
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{
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unsigned int ret;
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ret = __kfifo_from_user_n(fifo, from, n, recsize);
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if (likely(ret == 0)) {
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if (recsize)
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__kfifo_poke_n(fifo, recsize, n);
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__kfifo_add_in(fifo, n + recsize);
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}
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return ret;
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}
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/**
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* kfifo_from_user_rec - puts some data from user space into the FIFO
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* @fifo: the fifo to be used.
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* @from: pointer to the data to be added.
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* @n: the length of the data to be added.
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* @recsize: size of record field
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*
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* This function copies @n bytes from the @from into the
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* FIFO and returns the number of bytes which cannot be copied.
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*
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* If the returned value is equal or less the @n value, the copy_from_user()
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* functions has failed. Otherwise the record doesn't fit into the buffer.
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*
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* Note that with only one concurrent reader and one concurrent
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* writer, you don't need extra locking to use these functions.
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*/
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static inline __must_check unsigned int kfifo_from_user_rec(struct kfifo *fifo,
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const void __user *from, unsigned int n, unsigned int recsize)
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{
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if (!__builtin_constant_p(recsize))
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return __kfifo_from_user_generic(fifo, from, n, recsize);
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return __kfifo_from_user_rec(fifo, from, n, recsize);
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}
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/*
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* __kfifo_to_user_... internal functions for transfer fifo data into user space
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* do not call it directly, use kfifo_to_user_rec() instead
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*/
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extern unsigned int __kfifo_to_user_n(struct kfifo *fifo,
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void __user *to, unsigned int n, unsigned int reclen,
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unsigned int recsize);
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extern unsigned int __kfifo_to_user_generic(struct kfifo *fifo,
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void __user *to, unsigned int n, unsigned int recsize,
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unsigned int *total);
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static inline unsigned int __kfifo_to_user_rec(struct kfifo *fifo,
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void __user *to, unsigned int n,
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unsigned int recsize, unsigned int *total)
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{
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unsigned int l;
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if (!recsize) {
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l = n;
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if (total)
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*total = l;
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} else {
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l = __kfifo_peek_n(fifo, recsize);
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if (total)
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*total = l;
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if (n < l)
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return l;
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}
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return __kfifo_to_user_n(fifo, to, n, l, recsize);
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}
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/**
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* kfifo_to_user_rec - gets data from the FIFO and write it to user space
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* @fifo: the fifo to be used.
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* @to: where the data must be copied.
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* @n: the size of the destination buffer.
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* @recsize: size of record field
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* @total: pointer where the total number of to copied bytes should stored
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*
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* This function copies at most @n bytes from the FIFO to the @to.
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* In case of an error, the function returns the number of bytes which cannot
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* be copied.
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* If the returned value is equal or less the @n value, the copy_to_user()
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* functions has failed. Otherwise the record doesn't fit into the @to buffer.
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*
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* Note that with only one concurrent reader and one concurrent
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* writer, you don't need extra locking to use these functions.
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*/
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static inline __must_check unsigned int kfifo_to_user_rec(struct kfifo *fifo,
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void __user *to, unsigned int n, unsigned int recsize,
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|
unsigned int *total)
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{
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if (!__builtin_constant_p(recsize))
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return __kfifo_to_user_generic(fifo, to, n, recsize, total);
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return __kfifo_to_user_rec(fifo, to, n, recsize, total);
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}
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/*
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* __kfifo_peek_... internal functions for peek into the next fifo record
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* do not call it directly, use kfifo_peek_rec() instead
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*/
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extern unsigned int __kfifo_peek_generic(struct kfifo *fifo,
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|
unsigned int recsize);
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|
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/**
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|
* kfifo_peek_rec - gets the size of the next FIFO record data
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|
* @fifo: the fifo to be used.
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* @recsize: size of record field
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*
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* This function returns the size of the next FIFO record in number of bytes
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*/
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static inline __must_check unsigned int kfifo_peek_rec(struct kfifo *fifo,
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|
unsigned int recsize)
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{
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if (!__builtin_constant_p(recsize))
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return __kfifo_peek_generic(fifo, recsize);
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if (!recsize)
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return kfifo_len(fifo);
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return __kfifo_peek_n(fifo, recsize);
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}
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/*
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* __kfifo_skip_... internal functions for skip the next fifo record
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|
* do not call it directly, use kfifo_skip_rec() instead
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|
*/
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|
extern void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize);
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|
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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);
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|
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;
|
|
}
|
|
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|
#endif
|