The patch titled
Subject: kfifo: add kfifo_out_linear{,_ptr}()
has been added to the -mm mm-nonmm-unstable branch. Its filename is
kfifo-add-kfifo_out_linear_ptr.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kfifo-add-kfifo_out_linear_ptr.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Jiri Slaby (SUSE)" <jirislaby@xxxxxxxxxx>
Subject: kfifo: add kfifo_out_linear{,_ptr}()
Date: Fri, 23 Feb 2024 12:51:54 +0100
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.
Link: https://lkml.kernel.org/r/20240223115155.8806-4-jirislaby@xxxxxxxxxx
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx>
Cc: Stefani Seibold <stefani@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kfifo.h | 64 ++++++++++++++++++++++++++++++++++++++++
lib/kfifo.c | 28 +++++++++++++++++
2 files changed, 92 insertions(+)
--- a/include/linux/kfifo.h~kfifo-add-kfifo_out_linear_ptr
+++ a/include/linux/kfifo.h
@@ -827,6 +827,64 @@ __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)); \
+ struct __kfifo *___kfifo = &___tmp->kfifo; \
+ *(ptr) = ___kfifo->data + ___tail * kfifo_esize(___tmp); \
+ ___n; \
+}) \
+)
+
+
extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
size_t esize, gfp_t gfp_mask);
@@ -856,6 +914,9 @@ extern unsigned int __kfifo_dma_out_prep
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);
@@ -885,6 +946,9 @@ extern void __kfifo_skip_r(struct __kfif
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
--- a/lib/kfifo.c~kfifo-add-kfifo_out_linear_ptr
+++ a/lib/kfifo.c
@@ -163,6 +163,21 @@ unsigned int __kfifo_out_peek(struct __k
}
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;
+
+ n = min3(n, fifo->in - fifo->out, size - off);
+
+ if (tail)
+ *tail = off;
+
+ return n;
+}
+EXPORT_SYMBOL(__kfifo_out_linear);
+
unsigned int __kfifo_out(struct __kfifo *fifo,
void *buf, unsigned int len)
{
@@ -473,6 +488,19 @@ unsigned int __kfifo_out_peek_r(struct _
}
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)
{
_
Patches currently in -mm which might be from jirislaby@xxxxxxxxxx are
kfifo-drop-__kfifo_dma_out_finish_r.patch
kfifo-introduce-and-use-kfifo_skip_count.patch
kfifo-add-kfifo_out_linear_ptr.patch
kfifo-fix-typos-in-kernel-doc.patch
