From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965393AbXCFRkW (ORCPT ); Tue, 6 Mar 2007 12:40:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965380AbXCFRkW (ORCPT ); Tue, 6 Mar 2007 12:40:22 -0500 Received: from mx1.redhat.com ([66.187.233.31]:46852 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965396AbXCFRkV (ORCPT ); Tue, 6 Mar 2007 12:40:21 -0500 From: David Howells Subject: [PATCH] Fix get_order() To: torvalds@osdl.org, akpm@osdl.org, benh@kernel.crashing.org Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, johannes@sipsolutions.net, dhowells@redhat.com Date: Tue, 06 Mar 2007 17:39:29 +0000 Message-ID: <20070306173929.2708.37191.stgit@warthog.cambridge.redhat.com> User-Agent: StGIT/0.12.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: David Howells Fix get_order() to use ilog2() properly. Signed-Off-By: David Howells --- include/asm-generic/page.h | 14 +++++++++++--- include/linux/log2.h | 20 ++++++++++++++++++-- 2 files changed, 29 insertions(+), 5 deletions(-) diff --git a/include/asm-generic/page.h b/include/asm-generic/page.h index b55052c..c37571d 100644 --- a/include/asm-generic/page.h +++ b/include/asm-generic/page.h @@ -17,10 +17,18 @@ static inline __attribute__((const)) int __get_order(unsigned long size, int page_shift) { #if BITS_PER_LONG == 32 && defined(ARCH_HAS_ILOG2_U32) - int order = __ilog2_u32(size) - page_shift; + int order; + if (size <= 1) + order = 0; + else + order = __ilog2_u32(size - 1) + 1 - page_shift; return order >= 0 ? order : 0; #elif BITS_PER_LONG == 64 && defined(ARCH_HAS_ILOG2_U64) - int order = __ilog2_u64(size) - page_shift; + int order; + if (size <= 1) + order = 0; + else + order = __ilog2_u64(size - 1) + 1 - page_shift; return order >= 0 ? order : 0; #else int order; @@ -46,7 +54,7 @@ int __get_order(unsigned long size, int page_shift) #define get_order(n) \ ( \ __builtin_constant_p(n) ? \ - ((n < (1UL << PAGE_SHIFT)) ? 0 : ilog2(n) - PAGE_SHIFT) : \ + ((n < (1UL << PAGE_SHIFT)) ? 0 : ilog2_up(n) - PAGE_SHIFT) : \ __get_order(n, PAGE_SHIFT) \ ) diff --git a/include/linux/log2.h b/include/linux/log2.h index 57e641e..bc3a0eb 100644 --- a/include/linux/log2.h +++ b/include/linux/log2.h @@ -70,6 +70,8 @@ unsigned long __roundup_pow_of_two(unsigned long n) * constant-capable log of base 2 calculation * - this can be used to initialise global variables from constant data, hence * the massive ternary operator construction + * - the result is rounded down + * - the result is undefined when n < 1 * * selects the appropriately-sized optimised version depending on sizeof(n) */ @@ -149,6 +151,20 @@ unsigned long __roundup_pow_of_two(unsigned long n) ) /** + * ilog2_up - rounded up log of base 2 of 32-bit or a 64-bit unsigned value + * @n - parameter + * + * constant-capable log of base 2 calculation + * - this can be used to initialise global variables from constant data, hence + * the massive ternary operator construction + * - the result is rounded up + * - the result is undefined when n < 1 + * + * selects the appropriately-sized optimised version depending on sizeof(n) + */ +#define ilog2_up(n) ((n) == 1 ? 0 : ilog2((n) - 1) + 1) + +/** * roundup_pow_of_two - round the given value up to nearest power of two * @n - parameter * @@ -159,8 +175,8 @@ unsigned long __roundup_pow_of_two(unsigned long n) #define roundup_pow_of_two(n) \ ( \ __builtin_constant_p(n) ? ( \ - (n == 1) ? 0 : \ - (1UL << (ilog2((n) - 1) + 1)) \ + (n == 1) ? 1 : \ + (1UL << ilog2_up(n)) \ ) : \ __roundup_pow_of_two(n) \ )