From mboxrd@z Thu Jan 1 00:00:00 1970 From: Helge Deller Subject: Re: [PATCH] fix parisc runtime hangs wrt pa_tlb_lock Date: Wed, 17 Jun 2009 09:26:05 +0200 Message-ID: <4A389A8D.2010806@gmx.de> References: <20090528015037.3417E4FEA@hiauly1.hia.nrc.ca> <4A2ADEC9.2090403@gmx.de> <4A35741F.6000107@gmx.de> <20090614232046.GA14028@hiauly1.hia.nrc.ca> <4A3805E4.4080305@gmx.de> <20090617025529.GA19032@bombadil.infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: John David Anglin , linux-parisc@vger.kernel.org To: Kyle McMartin Return-path: In-Reply-To: <20090617025529.GA19032@bombadil.infradead.org> List-ID: List-Id: linux-parisc.vger.kernel.org On 06/17/2009 04:55 AM, Kyle McMartin wrote: > On Tue, Jun 16, 2009 at 10:51:48PM +0200, Helge Deller wrote: >> On 06/15/2009 01:20 AM, John David Anglin wrote: >>> I am convinced that interrupts need to be disabled on SMP kernels to >>> prevent deadlock. On UP kernels, I am not convinced that anything bad >>> happens if we do a tlb purge while handling an interrupt since we don't >>> have to worry about preventing bus conflicts. The UP code can't >>> deadlock. I'm thinking that we can stay with disabling preemption. >> Dave is right and it took me long to understand his point... >> I continued testing and we can simply just disable preemption for UP >> kernels and use an irq-safe spinlock for SMP kernels. >> >> Below is the latest and greatest patch which fixes this bug. >> Run-tested onUP kernels and compile-tested on SMP kernels. >> > > Ugh, I'd really prefer it if we just took the irq disable and enable hit > on UP by making the codepaths the same... Is that ok with you or? You mean to use the irq-safe spinlocking path for SMP _and_ UP? Yes, that would be ok for me too. We just thought why we should try to save some cycles on UP if possible, as the UP-kernel often is used on slower machines where it would be beneficial for them... If yes, do you want me to send an updated patch? Helge