From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754092AbcC1F7l (ORCPT ); Mon, 28 Mar 2016 01:59:41 -0400 Received: from mail-pa0-f45.google.com ([209.85.220.45]:34816 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753123AbcC1F7X (ORCPT ); Mon, 28 Mar 2016 01:59:23 -0400 From: js1304@gmail.com X-Google-Original-From: iamjoonsoo.kim@lge.com To: Andrew Morton Cc: Hugh Dickins , Johannes Berg , "David S. Miller" , Sunil Goutham , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim Subject: [PATCH 2/2] mm: rename _count, field of the struct page, to _refcount Date: Mon, 28 Mar 2016 14:59:08 +0900 Message-Id: <1459144748-13664-2-git-send-email-iamjoonsoo.kim@lge.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1459144748-13664-1-git-send-email-iamjoonsoo.kim@lge.com> References: <1459144748-13664-1-git-send-email-iamjoonsoo.kim@lge.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joonsoo Kim Many developer already know that field for reference count of the struct page is _count and atomic type. They would try to handle it directly and this could break the purpose of page reference count tracepoint. To prevent direct _count modification, this patch rename it to _refcount and add warning message on the code. After that, developer who need to handle reference count will find that field should not be accessed directly. Signed-off-by: Joonsoo Kim --- include/linux/mm_types.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 944b2b3..9e8eb5a 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -97,7 +97,11 @@ struct page { }; int units; /* SLOB */ }; - atomic_t _count; /* Usage count, see below. */ + /* + * Usage count, *USE WRAPPER FUNCTION* + * when manual accounting. See page_ref.h + */ + atomic_t _refcount; }; unsigned int active; /* SLAB */ }; @@ -248,7 +252,7 @@ struct page_frag_cache { __u32 offset; #endif /* we maintain a pagecount bias, so that we dont dirty cache line - * containing page->_count every time we allocate a fragment. + * containing page->_refcount every time we allocate a fragment. */ unsigned int pagecnt_bias; bool pfmemalloc; -- 1.9.1