From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH v3 2/4] genirq: Inform handler about line sharing state Date: Wed, 15 Dec 2010 10:37:59 +0100 Message-ID: <4D088C77.8030701@siemens.com> References: <4D07F738.8080204@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Jan Kiszka , Avi Kivity , Marcelo Tosatti , "linux-kernel@vger.kernel.org" , kvm , Tom Lyon , Alex Williamson , "Michael S. Tsirkin" To: Thomas Gleixner Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Am 15.12.2010 09:05, Thomas Gleixner wrote: > On Wed, 15 Dec 2010, Jan Kiszka wrote: > >> Am 14.12.2010 22:46, Thomas Gleixner wrote: >>> On Mon, 13 Dec 2010, Jan Kiszka wrote: >>>> From: Jan Kiszka >>>> chip_bus_lock(desc); >>>> retval = __setup_irq(irq, desc, action); >>>> chip_bus_sync_unlock(desc); >>>> >>>> - if (retval) >>>> + if (retval) { >>>> + if (desc->action && !desc->action->next) >>>> + desc->irq_data.drv_status &= ~IRQS_SHARED; >>> >>> This is redundant. IRQS_SHARED gets set in a code path where all >>> checks are done already. >> >> Nope, it's also set before entry of __setup_irq in case we call an >> IRQF_ADAPTIVE handler. >> >> We need to set it that early as we may race with IRQ events for the >> already registered handler happening between the sharing notification >> and the actual registration of the second handler. > > Hmm, ok. Though the MAKE_SHAREABLE flag should be sufficient to do the > notification. For notification, yes. But we need SHARED once we reenable the line after the notification. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux