Commit 2657df99 authored by Jiri Slaby (SUSE)'s avatar Jiri Slaby (SUSE) Committed by Zhao Yipeng
Browse files

kfifo: add kfifo_out_linear{,_ptr}() 

mainline inclusion
from mainline-v6.10-rc1
commit 4edd7e96a1f159f43bd1cb82616f81eaddd54262
category: feature
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAOXYG
CVE: CVE-2024-44951

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4edd7e96a1f159f43bd1cb82616f81eaddd54262



--------------------------------

kfifo: add kfifo_out_linear{,_ptr}()

These are helpers which are going to be used in the serial layer. We
need a wrapper around kfifo which provides us with a tail (sometimes
"tail" offset, sometimes a pointer) to the kfifo data. And which returns
count of available data -- but not larger than to the end of the buffer
(hence _linear in the names). I.e. something like CIRC_CNT_TO_END() in
the legacy circ_buf.

This patch adds such two helpers.

Signed-off-by: default avatarJiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20240405060826.2521-4-jirislaby@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarZhao Yipeng <zhaoyipeng5@huawei.com>
parent c275e006

include/linux/kfifo.h

+63 −0
Original line number Diff line number Diff line
@@ -828,6 +828,63 @@ __kfifo_uint_must_check_helper( \ 
}) \

)



/**

 * kfifo_out_linear - gets a tail of/offset to available data

 * @fifo: address of the fifo to be used

 * @tail: pointer to an unsigned int to store the value of tail

 * @n: max. number of elements to point at

 *

 * This macro obtains the offset (tail) to the available data in the fifo

 * buffer and returns the

 * numbers of elements available. It returns the available count till the end

 * of data or till the end of the buffer. So that it can be used for linear

 * data processing (like memcpy() of (@fifo->data + @tail) with count

 * returned).

 *

 * Note that with only one concurrent reader and one concurrent

 * writer, you don't need extra locking to use these macro.

 */

#define kfifo_out_linear(fifo, tail, n) \

__kfifo_uint_must_check_helper( \

({ \

	typeof((fifo) + 1) __tmp = (fifo); \

	unsigned int *__tail = (tail); \

	unsigned long __n = (n); \

	const size_t __recsize = sizeof(*__tmp->rectype); \

	struct __kfifo *__kfifo = &__tmp->kfifo; \

	(__recsize) ? \

	__kfifo_out_linear_r(__kfifo, __tail, __n, __recsize) : \

	__kfifo_out_linear(__kfifo, __tail, __n); \

}) \

)



/**

 * kfifo_out_linear_ptr - gets a pointer to the available data

 * @fifo: address of the fifo to be used

 * @ptr: pointer to data to store the pointer to tail

 * @n: max. number of elements to point at

 *

 * Similarly to kfifo_out_linear(), this macro obtains the pointer to the

 * available data in the fifo buffer and returns the numbers of elements

 * available. It returns the available count till the end of available data or

 * till the end of the buffer. So that it can be used for linear data

 * processing (like memcpy() of @ptr with count returned).

 *

 * Note that with only one concurrent reader and one concurrent

 * writer, you don't need extra locking to use these macro.

 */

#define kfifo_out_linear_ptr(fifo, ptr, n) \

__kfifo_uint_must_check_helper( \

({ \

	typeof((fifo) + 1) ___tmp = (fifo); \

	unsigned int ___tail; \

	unsigned int ___n = kfifo_out_linear(___tmp, &___tail, (n)); \

	*(ptr) = ___tmp->kfifo.data + ___tail * kfifo_esize(___tmp); \

	___n; \

}) \

)





extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,

	size_t esize, gfp_t gfp_mask);
@@ -857,6 +914,9 @@ extern unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo, 
extern unsigned int __kfifo_out_peek(struct __kfifo *fifo,

	void *buf, unsigned int len);



extern unsigned int __kfifo_out_linear(struct __kfifo *fifo,

	unsigned int *tail, unsigned int n);



extern unsigned int __kfifo_in_r(struct __kfifo *fifo,

	const void *buf, unsigned int len, size_t recsize);
@@ -888,6 +948,9 @@ extern void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize); 
extern unsigned int __kfifo_out_peek_r(struct __kfifo *fifo,

	void *buf, unsigned int len, size_t recsize);



extern unsigned int __kfifo_out_linear_r(struct __kfifo *fifo,

	unsigned int *tail, unsigned int n, size_t recsize);



extern unsigned int __kfifo_max_r(unsigned int len, size_t recsize);



#endif

lib/kfifo.c

+26 −0
Original line number Diff line number Diff line
@@ -163,6 +163,19 @@ unsigned int __kfifo_out_peek(struct __kfifo *fifo, 
}

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)

{
@@ -473,6 +486,19 @@ unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf, 
}

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)

{