From: Sascha Hauer <s.hauer@pengutronix.de>
To: Barebox List <barebox@lists.infradead.org>
Subject: [PATCH] kfifo: roundup fifo size to next power of two
Date: Fri, 21 Sep 2018 13:14:05 +0200 [thread overview]
Message-ID: <20180921111405.26959-1-s.hauer@pengutronix.de> (raw)
Comments in include/kfifo.h state that the FIFO size will be rounded up
to the next power of two, but so far we haven't actually done this,
probably because we didn't have roundup_pow_of_two() back then when
kfifo support was added.
Fix that now and do what the comments state.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
lib/kfifo.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/lib/kfifo.c b/lib/kfifo.c
index 307dae1441..fa22feb7e0 100644
--- a/lib/kfifo.c
+++ b/lib/kfifo.c
@@ -18,6 +18,7 @@
#include <malloc.h>
#include <kfifo.h>
#include <errno.h>
+#include <linux/log2.h>
/**
* kfifo_init - allocates a new FIFO using a preallocated buffer
@@ -49,6 +50,15 @@ struct kfifo *kfifo_alloc(unsigned int size)
unsigned char *buffer;
struct kfifo *fifo;
+ /*
+ * round up to the next power of 2, since our 'let the indices
+ * wrap' tachnique works only in this case.
+ */
+ if (size & (size - 1)) {
+ BUG_ON(size > 0x80000000);
+ size = roundup_pow_of_two(size);
+ }
+
buffer = malloc(size);
if (!buffer)
return NULL;
--
2.19.0
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