From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yk0-f179.google.com (mail-yk0-f179.google.com [209.85.160.179]) by kanga.kvack.org (Postfix) with ESMTP id 0F9BD6B0035 for ; Tue, 12 Aug 2014 19:30:02 -0400 (EDT) Received: by mail-yk0-f179.google.com with SMTP id 142so7745835ykq.38 for ; Tue, 12 Aug 2014 16:30:01 -0700 (PDT) Received: from g4t3426.houston.hp.com (g4t3426.houston.hp.com. [15.201.208.54]) by mx.google.com with ESMTPS id x61si151680yhk.194.2014.08.12.16.30.01 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 12 Aug 2014 16:30:01 -0700 (PDT) Message-ID: <1407886188.2695.3.camel@buesod1.americas.hpqcorp.net> Subject: Re: [PATCH] mm: introduce for_each_vma helpers From: Davidlohr Bueso Date: Tue, 12 Aug 2014 16:29:48 -0700 In-Reply-To: <20140812215213.GB17497@node.dhcp.inet.fi> References: <1407865523.2633.3.camel@buesod1.americas.hpqcorp.net> <20140812215213.GB17497@node.dhcp.inet.fi> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Andrew Morton , Martin Schwidefsky , Heiko Carstens , "James E.J. Bottomley" , Helge Deller , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Robert Richter , linux-mm@kvack.org, linux-kernel@vger.kernel.org, aswin@hp.com On Wed, 2014-08-13 at 00:52 +0300, Kirill A. Shutemov wrote: > On Tue, Aug 12, 2014 at 10:45:23AM -0700, Davidlohr Bueso wrote: > > The most common way of iterating through the list of vmas, is via: > > for (vma = mm->mmap; vma; vma = vma->vm_next) > > > > This patch replaces this logic with a new for_each_vma(vma) helper, > > which 1) encapsulates this logic, and 2) make it easier to read. > > Why does it need to be encapsulated? > Do you have problem with reading plain for()? No problem in particular. But encapsulation is always good to have, and we have a number of examples similar to what I'm proposing all throughout the kernel (just like at vma_interval_tree_foreach). > Your for_each_vma(vma) assumes "mm" from the scope. This can be confusing > for reader: whether it uses "mm" from the scope or "current->mm". This > will lead to very hard to find bug one day. > I don't like this. > > > It also updates most of the callers, so its a pretty good start. > > > > Similarly, we also have for_each_vma_start(vma, start) when the user > > does not want to start at the beginning of the list. And lastly the > > for_each_vma_start_inc(vma, start, inc) helper in introduced to allow > > users to create higher level special vma abstractions, such as with > > the case of ELF binaries. > > for_each_vma_start_inc() is pretty much the plain for() but with > really_long_and_fancy_name(). Why? Because we can implement things like for_each_vma_gate() on top. Thanks, Davidlohr -- 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