// SPDX-License-Identifier: GPL-2.0-or-later/* * A generic kernel FIFO implementation * * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net> */ #include <linux/dma-mapping.h>#include <linux/err.h>#include <linux/export.h>#include <linux/kfifo.h>#include <linux/log2.h>#include <linux/scatterlist.h>#include <linux/slab.h>#include <linux/uaccess.h> /* * internal helper to calculate the unused elements in a fifo */static inline unsigned int kfifo_unused(struct __kfifo *fifo){	return (fifo->mask + 1) - (fifo->in - fifo->out);} int __kfifo_alloc_node(struct __kfifo *fifo, unsigned int size,		size_t esize, gfp_t gfp_mask, int node){	/*	 * round up to the next power of 2, since our 'let the indices	 * wrap' technique works only in this case.	 */	size = roundup_pow_of_two(size); 	fifo->in = 0;	fifo->out = 0;	fifo->esize = esize; 	if (size < 2) {		fifo->data = NULL;		fifo->mask = 0;		return -EINVAL;	} 	fifo->data = kmalloc_array_node(size, esize, gfp_mask, node); 	if (!fifo->data) {		fifo->mask = 0;		return -ENOMEM;	}	fifo->mask = size - 1; 	return 0;}EXPORT_SYMBOL(__kfifo_alloc_node); void __kfifo_free(struct __kfifo *fifo){	kfree(fifo->data);	fifo->in = 0;	fifo->out = 0;	fifo->esize = 0;	fifo->data = NULL;	fifo->mask = 0;}EXPORT_SYMBOL(__kfifo_free); int __kfifo_init(struct __kfifo *fifo, void *buffer,		unsigned int size, size_t esize){	size /= esize; 	if (!is_power_of_2(size))		size = rounddown_pow_of_two(size); 	fifo->in = 0;	fifo->out = 0;	fifo->esize = esize;	fifo->data = buffer; 	if (size < 2) {		fifo->mask = 0;		return -EINVAL;	}	fifo->mask = size - 1; 	return 0;}EXPORT_SYMBOL(__kfifo_init); static void kfifo_copy_in(struct __kfifo *fifo, const void *src,		unsigned int len, unsigned int off){	unsigned int size = fifo->mask + 1;	unsigned int esize = fifo->esize;	unsigned int l; 	off &= fifo->mask;	if (esize != 1) {		off *= esize;		size *= esize;		len *= esize;	}	l = min(len, size - off); 	memcpy(fifo->data + off, src, l);	memcpy(fifo->data, src + l, len - l);	/*	 * make sure that the data in the fifo is up to date before	 * incrementing the fifo->in index counter	 */	smp_wmb();} unsigned int __kfifo_in(struct __kfifo *fifo,		const void *buf, unsigned int len){	unsigned int l; 	l = kfifo_unused(fifo);	if (len > l)		len = l; 	kfifo_copy_in(fifo, buf, len, fifo->in);	fifo->in += len;	return len;}EXPORT_SYMBOL(__kfifo_in); static void kfifo_copy_out(struct __kfifo *fifo, void *dst,		unsigned int len, unsigned int off){	unsigned int size = fifo->mask + 1;	unsigned int esize = fifo->esize;	unsigned int l; 	off &= fifo->mask;	if (esize != 1) {		off *= esize;		size *= esize;		len *= esize;	}	l = min(len, size - off); 	memcpy(dst, fifo->data + off, l);	memcpy(dst + l, fifo->data, len - l);	/*	 * make sure that the data is copied before	 * incrementing the fifo->out index counter	 */	smp_wmb();} unsigned int __kfifo_out_peek(struct __kfifo *fifo,		void *buf, unsigned int len){	unsigned int l; 	l = fifo->in - fifo->out;	if (len > l)		len = l; 	kfifo_copy_out(fifo, buf, len, fifo->out);	return len;}EXPORT_SYMBOL(__kfifo_out_peek); unsigned int __kfifo_out_linear(struct __kfifo *fifo,		unsigned int *tail, unsigned int n){	unsigned int size = fifo->mask + 1;	unsigned int off = fifo->out & fifo->mask; 	if (tail)		*tail = off; 	return min3(n, fifo->in - fifo->out, size - off);}EXPORT_SYMBOL(__kfifo_out_linear); unsigned int __kfifo_out(struct __kfifo *fifo,		void *buf, unsigned int len){	len = __kfifo_out_peek(fifo, buf, len);	fifo->out += len;	return len;}EXPORT_SYMBOL(__kfifo_out); static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,	const void __user *from, unsigned int len, unsigned int off,	unsigned int *copied){	unsigned int size = fifo->mask + 1;	unsigned int esize = fifo->esize;	unsigned int l;	unsigned long ret; 	off &= fifo->mask;	if (esize != 1) {		off *= esize;		size *= esize;		len *= esize;	}	l = min(len, size - off); 	ret = copy_from_user(fifo->data + off, from, l);	if (unlikely(ret))		ret = DIV_ROUND_UP(ret + len - l, esize);	else {		ret = copy_from_user(fifo->data, from + l, len - l);		if (unlikely(ret))			ret = DIV_ROUND_UP(ret, esize);	}	/*	 * make sure that the data in the fifo is up to date before	 * incrementing the fifo->in index counter	 */	smp_wmb();	*copied = len - ret * esize;	/* return the number of elements which are not copied */	return ret;} int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,		unsigned long len, unsigned int *copied){	unsigned int l;	unsigned long ret;	unsigned int esize = fifo->esize;	int err; 	if (esize != 1)		len /= esize; 	l = kfifo_unused(fifo);	if (len > l)		len = l; 	ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);	if (unlikely(ret)) {		len -= ret;		err = -EFAULT;	} else		err = 0;	fifo->in += len;	return err;}EXPORT_SYMBOL(__kfifo_from_user); static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,		unsigned int len, unsigned int off, unsigned int *copied){	unsigned int l;	unsigned long ret;	unsigned int size = fifo->mask + 1;	unsigned int esize = fifo->esize; 	off &= fifo->mask;	if (esize != 1) {		off *= esize;		size *= esize;		len *= esize;	}	l = min(len, size - off); 	ret = copy_to_user(to, fifo->data + off, l);	if (unlikely(ret))		ret = DIV_ROUND_UP(ret + len - l, esize);	else {		ret = copy_to_user(to + l, fifo->data, len - l);		if (unlikely(ret))			ret = DIV_ROUND_UP(ret, esize);	}	/*	 * make sure that the data is copied before	 * incrementing the fifo->out index counter	 */	smp_wmb();	*copied = len - ret * esize;	/* return the number of elements which are not copied */	return ret;} int __kfifo_to_user(struct __kfifo *fifo, void __user *to,		unsigned long len, unsigned int *copied){	unsigned int l;	unsigned long ret;	unsigned int esize = fifo->esize;	int err; 	if (esize != 1)		len /= esize; 	l = fifo->in - fifo->out;	if (len > l)		len = l;	ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);	if (unlikely(ret)) {		len -= ret;		err = -EFAULT;	} else		err = 0;	fifo->out += len;	return err;}EXPORT_SYMBOL(__kfifo_to_user); static unsigned int setup_sgl_buf(struct __kfifo *fifo, struct scatterlist *sgl,				  unsigned int data_offset, int nents,				  unsigned int len, dma_addr_t dma){	const void *buf = fifo->data + data_offset; 	if (!nents || !len)		return 0; 	sg_set_buf(sgl, buf, len); 	if (dma != DMA_MAPPING_ERROR) {		sg_dma_address(sgl) = dma + data_offset;		sg_dma_len(sgl) = len;	} 	return 1;} static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,		int nents, unsigned int len, unsigned int off, dma_addr_t dma){	unsigned int size = fifo->mask + 1;	unsigned int esize = fifo->esize;	unsigned int len_to_end;	unsigned int n; 	off &= fifo->mask;	if (esize != 1) {		off *= esize;		size *= esize;		len *= esize;	}	len_to_end = min(len, size - off); 	n = setup_sgl_buf(fifo, sgl, off, nents, len_to_end, dma);	n += setup_sgl_buf(fifo, sgl + n, 0, nents - n, len - len_to_end, dma); 	return n;} unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,		struct scatterlist *sgl, int nents, unsigned int len,		dma_addr_t dma){	unsigned int l; 	l = kfifo_unused(fifo);	if (len > l)		len = l; 	return setup_sgl(fifo, sgl, nents, len, fifo->in, dma);}EXPORT_SYMBOL(__kfifo_dma_in_prepare); unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,		struct scatterlist *sgl, int nents, unsigned int len,		dma_addr_t dma){	unsigned int l; 	l = fifo->in - fifo->out;	if (len > l)		len = l; 	return setup_sgl(fifo, sgl, nents, len, fifo->out, dma);}EXPORT_SYMBOL(__kfifo_dma_out_prepare); unsigned int __kfifo_max_r(unsigned int len, size_t recsize){	unsigned int max = (1 << (recsize << 3)) - 1; 	if (len > max)		return max;	return len;}EXPORT_SYMBOL(__kfifo_max_r); #define	__KFIFO_PEEK(data, out, mask) \	((data)[(out) & (mask)])/* * __kfifo_peek_n internal helper function for determinate the length of * the next record in the fifo */static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize){	unsigned int l;	unsigned int mask = fifo->mask;	unsigned char *data = fifo->data; 	l = __KFIFO_PEEK(data, fifo->out, mask); 	if (--recsize)		l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8; 	return l;} #define	__KFIFO_POKE(data, in, mask, val) \	( \	(data)[(in) & (mask)] = (unsigned char)(val) \	) /* * __kfifo_poke_n internal helper function for storing the length of * the record into the fifo */static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize){	unsigned int mask = fifo->mask;	unsigned char *data = fifo->data; 	__KFIFO_POKE(data, fifo->in, mask, n); 	if (recsize > 1)		__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);} unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize){	return __kfifo_peek_n(fifo, recsize);}EXPORT_SYMBOL(__kfifo_len_r); unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,		unsigned int len, size_t recsize){	if (len + recsize > kfifo_unused(fifo))		return 0; 	__kfifo_poke_n(fifo, len, recsize); 	kfifo_copy_in(fifo, buf, len, fifo->in + recsize);	fifo->in += len + recsize;	return len;}EXPORT_SYMBOL(__kfifo_in_r); static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,	void *buf, unsigned int len, size_t recsize, unsigned int *n){	*n = __kfifo_peek_n(fifo, recsize); 	if (len > *n)		len = *n; 	kfifo_copy_out(fifo, buf, len, fifo->out + recsize);	return len;} unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,		unsigned int len, size_t recsize){	unsigned int n; 	if (fifo->in == fifo->out)		return 0; 	return kfifo_out_copy_r(fifo, buf, len, recsize, &n);}EXPORT_SYMBOL(__kfifo_out_peek_r); unsigned int __kfifo_out_linear_r(struct __kfifo *fifo,		unsigned int *tail, unsigned int n, size_t recsize){	if (fifo->in == fifo->out)		return 0; 	if (tail)		*tail = fifo->out + recsize; 	return min(n, __kfifo_peek_n(fifo, recsize));}EXPORT_SYMBOL(__kfifo_out_linear_r); unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,		unsigned int len, size_t recsize){	unsigned int n; 	if (fifo->in == fifo->out)		return 0; 	len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);	fifo->out += n + recsize;	return len;}EXPORT_SYMBOL(__kfifo_out_r); void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize){

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