From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 368856B00A8 for ; Mon, 23 Feb 2009 09:02:06 -0500 (EST) From: Nick Piggin Subject: Re: [patch 1/7] slab: introduce kzfree() Date: Tue, 24 Feb 2009 01:01:24 +1100 References: <499BE7F8.80901@csr.com> <499DB6EC.3020904@cs.helsinki.fi> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200902240101.26362.nickpiggin@yahoo.com.au> Sender: owner-linux-mm@kvack.org To: Hugh Dickins Cc: Pekka Enberg , Matt Mackall , KOSAKI Motohiro , David Vrabel , Johannes Weiner , Andrew Morton , Chas Williams , Evgeniy Polyakov , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Lameter , Nick Piggin List-ID: On Friday 20 February 2009 07:36:48 Hugh Dickins wrote: > On Thu, 19 Feb 2009, Pekka Enberg wrote: > > Quite frankly, I fail to see how kzfree() is fundamentally different from > > kfree(). I don't see kzfree() as a memset() + kfree() but rather as a > > kfree() "and make sure no one sees my data". So the zeroing happens > > _after_ you've invalidated the pointer with kzfree() so there's no > > "zeroing of buffer going on". > > Well, that would be one way of picturing it, yes. > Imagine the "z" as for "zap" rather than "zero", > and the mechanism as opaque as Hannes suggests. > > > So the way I see it, Linus' argument for having const for kfree() applies > > to kzfree(). > > > > That said, if you guys think it's a merge blocker, by all means remove > > the const. I just want few less open-coded ksize() users, that's all. > > I wouldn't call it a merge blocker, no; though I still > think it makes far more sense without the "const" there. Well, the buffer is only non-modified in the case of one of the allocators (SLAB). All others overwrite some of the data region with their own metadata. I think it is OK to use const, though. Because k(z)free has the knowledge that the data will not be touched by the caller any longer. -- 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