From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: [PATCH 2/3] Adjust the comment on get_order() to describe the size==0 case Date: Tue, 13 Dec 2011 14:57:05 +0000 Message-ID: <20111213145704.14362.62471.stgit@warthog.procyon.org.uk> References: <20111213145654.14362.39868.stgit@warthog.procyon.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:7076 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753324Ab1LMO5S (ORCPT ); Tue, 13 Dec 2011 09:57:18 -0500 In-Reply-To: <20111213145654.14362.39868.stgit@warthog.procyon.org.uk> Sender: linux-arch-owner@vger.kernel.org List-ID: To: tglx@linutronix.de, mingo@redhat.com Cc: x86@kernel.org, linux-arch@vger.kernel.org, David Howells Adjust the comment on get_order() to note that the result of passing a size of 0 results in an undefined value. Signed-off-by: David Howells --- include/asm-generic/getorder.h | 23 ++++++++++++++++++++++- 1 files changed, 22 insertions(+), 1 deletions(-) diff --git a/include/asm-generic/getorder.h b/include/asm-generic/getorder.h index 67e7245..76e9687 100644 --- a/include/asm-generic/getorder.h +++ b/include/asm-generic/getorder.h @@ -5,7 +5,28 @@ #include -/* Pure 2^n version of get_order */ +/** + * get_order - Determine the allocation order of a memory size + * @size: The size for which to get the order + * + * Determine the allocation order of a particular sized block of memory. This + * is on a logarithmic scale, where: + * + * 0 -> 2^0 * PAGE_SIZE and below + * 1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1 + * 2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1 + * 3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1 + * 4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1 + * ... + * + * The order returned is used to find the smallest allocation granule required + * to hold an object of the specified size. + * + * The result is undefined if the size is 0. + * + * This function may be used to initialise variables with compile time + * evaluations of constants. + */ static inline __attribute_const__ int get_order(unsigned long size) { int order;