From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx101.postini.com [74.125.245.101]) by kanga.kvack.org (Postfix) with SMTP id B8D036B0083 for ; Tue, 22 May 2012 16:11:01 -0400 (EDT) Date: Tue, 22 May 2012 13:10:59 -0700 From: Andrew Morton Subject: Re: [PATCH v3] scatterlist: add sg_alloc_table_from_pages function Message-Id: <20120522131059.415a881c.akpm@linux-foundation.org> In-Reply-To: <4FBA4ACE.4080602@samsung.com> References: <4FA8EC69.8010805@samsung.com> <20120517165614.d5e6e4b6.akpm@linux-foundation.org> <4FBA4ACE.4080602@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Tomasz Stanislawski Cc: paul.gortmaker@windriver.com, =?UTF-8?Q?'=EB=B0=95=EA=B2=BD=EB=AF=BC'?= , amwang@redhat.com, dri-devel@lists.freedesktop.org, "'???/Mobile S/W Platform Lab.(???)/E3(??)/????'" , prashanth.g@samsung.com, Marek Szyprowski , "linux-media@vger.kernel.org" , Laurent Pinchart , Rob Clark , Dave Airlie , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andy Whitcroft , Johannes Weiner On Mon, 21 May 2012 16:01:50 +0200 Tomasz Stanislawski wrote: > >> +int sg_alloc_table_from_pages(struct sg_table *sgt, > >> + struct page **pages, unsigned int n_pages, > >> + unsigned long offset, unsigned long size, > >> + gfp_t gfp_mask) > > > > I guess a 32-bit n_pages is OK. A 16TB IO seems enough ;) > > > > Do you think that 'unsigned long' for offset is too big? > > Ad n_pages. Assuming that Moore's law holds it will take > circa 25 years before the limit of 16 TB is reached :) for > high-end scatterlist operations. > Or I can change the type of n_pages to 'unsigned long' now at > no cost :). By then it will be Someone Else's Problem ;) > >> +{ > >> + unsigned int chunks; > >> + unsigned int i; > > > > erk, please choose a different name for this. When a C programmer sees > > "i", he very much assumes it has type "int". Making it unsigned causes > > surprise. > > > > And don't rename it to "u"! Let's give it a nice meaningful name. pageno? > > > > The problem is that 'i' is a natural name for a loop counter. It's also the natural name for an integer. If a C programmer sees "i", he thinks "int". It's a Fortran thing ;) > AFAIK, in the kernel code developers try to avoid Hungarian notation. > A name of a variable should reflect its purpose, not its type. > I can change the name of 'i' to 'pageno' and 'j' to 'pageno2' (?) > but I think it will make the code less reliable. Well, one could do something radical such as using "p". -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org