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kfifo: add kfifo_out_linear{,_ptr}()

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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: Jiri 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby (SUSE)
2024-04-05 08:08:14 +02:00
committed by Greg Kroah-Hartman
parent 76738194be
commit 4edd7e96a1
2 changed files with 89 additions and 0 deletions
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26
lib/kfifo.c
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@@ -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)
{