From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx199.postini.com [74.125.245.199]) by kanga.kvack.org (Postfix) with SMTP id E1E006B004D for ; Sat, 21 Jan 2012 14:44:36 -0500 (EST) Message-ID: <4F1B2356.4040302@xenotime.net> Date: Sat, 21 Jan 2012 12:43:02 -0800 From: Randy Dunlap MIME-Version: 1.0 Subject: Re: [PATCH 1/3] idr: make idr_get_next() good for rcu_read_lock() References: <1326958401.1113.22.camel@edumazet-laptop> <1326979818.2249.12.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> <20120120154807.c55c9ac7.akpm@linux-foundation.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Hugh Dickins Cc: Andrew Morton , Tejun Heo , Eric Dumazet , Li Zefan , Manfred Spraul , KAMEZAWA Hiroyuki , Johannes Weiner , Ying Han , Greg Thelen , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On 01/20/2012 07:45 PM, Hugh Dickins wrote: > On Fri, 20 Jan 2012, Andrew Morton wrote: >> On Thu, 19 Jan 2012 12:48:48 -0800 (PST) >> Hugh Dickins wrote: >>> Copied comment on RCU locking from idr_find(). >>> >>> + * >>> + * This function can be called under rcu_read_lock(), given that the leaf >>> + * pointers lifetimes are correctly managed. >> >> Awkward comment. It translates to "..., because the leaf pointers >> lifetimes are correctly managed". >> >> Is that what we really meant? Or did we mean "..., provided the leaf >> pointers lifetimes are correctly managed"? > > You are right, and part of me realized that even as I copied in the > comment. I wanted to express the same optimism for idr_get_next() > as was already expressed for idr_find() - whatever it meant ;) > > I thought it was meaning a bit of both: idr.c is managing its end well > enough that rcu_read_lock() can now be used, but the caller has to > manage their locking and lifetimes appropriately too. > >> >> Also, "pointers" should have been "pointer" or "pointer's"! > > You're afraid of Linus turning his "its/it's" wrath from Al to yourself. > > Since "lifetimes" is in the plural, I think it would have to be > "pointers'" - I _think_ that's correct, rather than "pointers's". That seems correct to me also. > But then, it's not the lifetimes of the pointers, but the lifetimes > of the objects that they point to, that's in question. So what it > ought to say is... > > ... falls asleep. ack. and thanks for doing all of that radix tree test harness work, Hugh. -- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** -- 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