Return-path: Subject: Re: [PATCH -v2 6/8] kexec jump: fix for lockdep From: Peter Zijlstra In-Reply-To: <1218416396.30464.9.camel@caritas-dev.intel.com> References: <1218178365.22039.79.camel@caritas-dev.intel.com> <1218190426.8625.71.camel@twins> <1218416396.30464.9.camel@caritas-dev.intel.com> Date: Mon, 11 Aug 2008 08:09:54 +0200 Message-Id: <1218434994.10800.16.camel@twins> Mime-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Huang Ying Cc: nigel@nigel.suspend2.net, Kexec Mailing List , linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , "Eric W. Biederman" , Pavel Machek , Andrew Morton , Linus Torvalds , mingo@elte.hu, Vivek Goyal On Mon, 2008-08-11 at 08:59 +0800, Huang Ying wrote: > On Fri, 2008-08-08 at 12:13 +0200, Peter Zijlstra wrote: > > On Fri, 2008-08-08 at 14:52 +0800, Huang Ying wrote: > > > Replace local_irq_disable() with raw_local_irq_disable() to prevent > > > lockdep complain. > > Uhhm, please provide more information - just using raw_* to silence > > lockdep is generally the wrong thing to do. > > In traditional kexec, the new kernel will replace current one, so the > irq is simply disabled. But now jumping back from kexeced kernel is > supported, so the irq should be enabled again. > > The code sequence of irq during kexec jump is as follow: > > local_irq_disable(); /* in kernel_kexec() */ > local_irq_disable(); /* in machine_kexec() */ > local_irq_enable(); /* in kernel_kexec() */ > > The disable and enable is not match. Maybe another method is to use > local_irq_save(), local_irq_restore() pair in machine_kexec(), so the > disable and enable is matched. And its the machine kernel's lockdep instance that goes complain? whichever annotation gets used - and I think I can agree that raw_* might be approriate there, this should be accompanied with a rather elaborate changelog and preferably a comment in the code too. Without such we'll be wondering in the years to come WTH happens here. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec