From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 5FBE56B00F5 for ; Fri, 6 Mar 2009 04:01:48 -0500 (EST) Message-ID: <49B0E67C.2090404@cn.fujitsu.com> Date: Fri, 06 Mar 2009 17:01:48 +0800 From: Li Zefan MIME-Version: 1.0 Subject: Re: [RFC][PATCH] kmemdup_from_user(): introduce References: <49B0CAEC.80801@cn.fujitsu.com> <20090306082056.GB3450@x200.localdomain> <49B0DE89.9000401@cn.fujitsu.com> <20090306003900.a031a914.akpm@linux-foundation.org> In-Reply-To: <20090306003900.a031a914.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Alexey Dobriyan , LKML , "linux-mm@kvack.org" List-ID: Andrew Morton wrote: > On Fri, 06 Mar 2009 16:27:53 +0800 Li Zefan wrote: > >>> Let's not add wrapper for every two lines that happen to be used >>> together. >>> >> Why not if we have good reasons? And I don't think we can call this >> "happen to" if there are 250+ of them? > > The change is a good one. If a reviewer (me) sees it then you know the > code's all right and the review effort becomes less - all you need to check > is that the call site is using IS_ERR/PTR_ERR and isn't testing for > NULL. Less code, less chance for bugs. > > Plus it makes kernel text smaller. > > Yes, the name is a bit cumbersome. > How about memdup_user()? like kstrndup() vs strndup_user(). Here is the statistics when using 5 kmemdup_from_user() in btrfs: $ diffstat ioctl.c | 49 ++++++++++++------------------------------------- super.c | 13 ++++--------- 2 files changed, 16 insertions(+), 46 deletions(-) the kernel size on i386: text data bss dec hex filename 288339 1924 508 290771 46fd3 fs/btrfs/btrfs.o.orig text data bss dec hex filename 288255 1924 508 290687 46f7f fs/btrfs/btrfs.o so saves 84 bytes. the kernel size on IA64: text data bss dec hex filename 898752 3736 109 902597 dc5c5 fs/btrfs/btrfs.o.orig text data bss dec hex filename 898176 3712 109 901997 dc36d fs/btrfs/btrfs.o so saves 576 bytes. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org