From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 8EB716B00F1 for ; Fri, 6 Mar 2009 03:56:26 -0500 (EST) Received: by fg-out-1718.google.com with SMTP id 19so468738fgg.4 for ; Fri, 06 Mar 2009 00:56:22 -0800 (PST) Date: Fri, 6 Mar 2009 12:03:13 +0300 From: Alexey Dobriyan Subject: Re: [RFC][PATCH] kmemdup_from_user(): introduce Message-ID: <20090306090313.GB4225@x200.localdomain> References: <49B0CAEC.80801@cn.fujitsu.com> <20090306082056.GB3450@x200.localdomain> <49B0DE89.9000401@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49B0DE89.9000401@cn.fujitsu.com> Sender: owner-linux-mm@kvack.org To: Li Zefan Cc: Andrew Morton , LKML , "linux-mm@kvack.org" List-ID: On Fri, Mar 06, 2009 at 04:27:53PM +0800, Li Zefan wrote: > Alexey Dobriyan wrote: > > On Fri, Mar 06, 2009 at 03:04:12PM +0800, Li Zefan wrote: > >> I notice there are many places doing copy_from_user() which follows > >> kmalloc(): > >> > >> dst = kmalloc(len, GFP_KERNEL); > >> if (!dst) > >> return -ENOMEM; > >> if (copy_from_user(dst, src, len)) { > >> kfree(dst); > >> return -EFAULT > >> } > >> > >> kmemdup_from_user() is a wrapper of the above code. With this new > >> function, we don't have to write 'len' twice, which can lead to > >> typos/mistakes. It also produces smaller code. > > > > Name totally sucks, it mixes kernel idiom of allocation with purely > > userspace function. > > > > I'm not good at English, and I don't know why "kernel memory duplicated > from user space" is so bad... > > or memdup_user() ? > > >> A qucik grep shows 250+ places where kmemdup_from_user() *may* be > >> used. I'll prepare a patchset to do this conversion. > > > > 250? > > > > I just found out how many copy_from_user() following km/zalloc(), so > not all of them are replace-able. > > > 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? Please, read through them. This "250+" number suddenly will become like 20, because wrapper is not good enough. -- 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