Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754039Ab1DVI7q (ORCPT ); Fri, 22 Apr 2011 04:59:46 -0400 Received: from mail-gy0-f174.google.com ([209.85.160.174]:61103 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752718Ab1DVI7n (ORCPT ); Fri, 22 Apr 2011 04:59:43 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=wUjxrzN/97FQZxHH5oQeTHxjSOcRJcN6KJV7wGAEG+nw2AgJIWbe5vgNckWWsShOp/ 36AMQxtmpxdlsYqb4RFOyKJiNnV59TIIGKWLCcRomCaV8d1RA4PHwbJKWoYQhO+aYGba 1fedByP40pMyYdSP88AD9ywCSsG0qRN+2vNcU= MIME-Version: 1.0 In-Reply-To: <201104220831.p3M8VgAO017323@www262.sakura.ne.jp> References: <20110417094505.865828233@chello.nl> <201104180341.p3I3fnxc000638@www262.sakura.ne.jp> <201104220744.p3M7indA004922@www262.sakura.ne.jp> <201104220831.p3M8VgAO017323@www262.sakura.ne.jp> Date: Fri, 22 Apr 2011 16:59:42 +0800 Message-ID: Subject: Re: [RFC][PATCH 0/7] lockdep: Support recurise-read locks From: Yong Zhang To: Tetsuo Handa Cc: a.p.zijlstra@chello.nl, rostedt@goodmis.org, tglx@linutronix.de, mingo@elte.hu, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1388 Lines: 38 2011/4/22 Tetsuo Handa : >> But if you call locktest1/locktest2 firstly, the chain will not be established >> just because recursive read is not added to prev->after. > > This part is not OK. At least, I think lockdep should be able to establish the > chain when locktest1 is called AGAIN after locktest2 is called (i.e. > "cat /proc/locktest1 /proc/locktest2 /proc/locktest1" case). I guess lockdep will warn on "cat /proc/locktest1 /proc/locktest2 /proc/locktest1" > But lockdep can > establish the chain for only "cat /proc/locktest2 /proc/locktest1" case. > I think there is a bug that prevents the lockdep from establishing the chain > when locktest1 is called AGAIN after locktest2 is called. If we want to fully support recursive read validation, it's a bug; but that also mean some head-burning work :) > If we can't fix the > bug, we should consider periodically (or upon printing stall warning messages) > revalidating already established chains. I don't think periodically revalidating make sense; because lockdep do validate everything real-time. Thanks, Yong -- Only stand for myself -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/