From	Ryan Cumming <>
Subject	Re: [RFC, 2.6] a simple FIFO implementation
Date	Sat, 18 Sep 2004 00:56:44 -0700
On Friday 17 September 2004 20:41, Kyle Moffett wrote:
This should probably be __const__, which is a stricter class of __pure__.
The "__pure__" attribute means it has no side effects, whereas the "__const__" attribute means that it also _only_ depends on its arguments,
not on any global memory or the data at any pointers passed to it.

Good call. I was just copying the __pure__ from long_log2 function in kernel.h, which looks like it should be __const__ too.
Here's a third try, with Andrew's and your suggestions.
-Ryan



--- a/include/linux/kernel.h	2004-09-16 06:38:19.000000000 -0700
+++ b/include/linux/kernel.h	2004-09-17 15:12:20.598844004 -0700
@@ -12,6 +12,7 @@
 #include <linux/stddef.h>
 #include <linux/types.h>
 #include <linux/compiler.h>
+#include <linux/bitops.h>
 #include <asm/byteorder.h>
 #include <asm/bug.h>
 
@@ -111,6 +112,10 @@
 	return r;
 }
 
+static inline unsigned long __attribute_const__ roundup_pow_of_two(unsigned long x)
+{
+	return (1UL << fls(x - 1));
+}
 
 extern int printk_ratelimit(void);
 extern int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst);