linux-kernel - [PATCH 2/3] add an inlined version of iter_div_u64

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Date:	Wed, 14 May 2008 16:48:05 +0100
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andi Kleen <andi@...stfloor.org>
Subject: [PATCH 2/3] add an inlined version of iter_div_u64_rem

iter_div_u64_rem is used in the x86-64 vdso, which cannot call other
kernel code.  For this case, provide the always_inlined version,
__iter_div_u64_rem.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
---
 include/linux/math64.h |   19 +++++++++++++++++++
 lib/div64.c            |   15 +--------------
 2 files changed, 20 insertions(+), 14 deletions(-)

===================================================================
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -83,4 +83,23 @@
 
 u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
 
+static __always_inline u32
+__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
+{
+	u32 ret = 0;
+
+	while (dividend >= divisor) {
+		/* The following asm() prevents the compiler from
+		   optimising this loop into a modulo operation.  */
+		asm("" : "+rm"(dividend));
+
+		dividend -= divisor;
+		ret++;
+	}
+
+	*remainder = dividend;
+
+	return ret;
+}
+
 #endif /* _LINUX_MATH64_H */
===================================================================
--- a/lib/div64.c
+++ b/lib/div64.c
@@ -105,19 +105,6 @@
  */
 u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
 {
-	u32 ret = 0;
-
-	while (dividend >= divisor) {
-		/* The following asm() prevents the compiler from
-		   optimising this loop into a modulo operation.  */
-		asm("" : "+rm"(dividend));
-
-		dividend -= divisor;
-		ret++;
-	}
-
-	*remainder = dividend;
-
-	return ret;
+	return __iter_div_u64_rem(dividend, divisor, remainder);
 }
 EXPORT_SYMBOL(iter_div_u64_rem);


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