From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: MSI interrupts and disable_irq Date: Mon, 15 Oct 2007 18:17:55 -0400 Message-ID: <4713E713.9060702@pobox.com> References: <46FC15A9.1070803@nvidia.com> <46FDBCB4.9090802@pobox.com> <4710901F.8010206@colorfullife.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Ayaz Abdulla , nedev , Linux Kernel Mailing List , David Miller , Andrew Morton To: Manfred Spraul Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:39684 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751431AbXJOWR7 (ORCPT ); Mon, 15 Oct 2007 18:17:59 -0400 In-Reply-To: <4710901F.8010206@colorfullife.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Manfred Spraul wrote: > Jeff Garzik wrote: >> >> I think the scenario you outline is an illustration of the approach's >> fragility: disable_irq() is a heavy hammer that originated with INTx, >> and it relies on a chip-specific disable method (kernel/irq/manage.c) >> that practically guarantees behavior will vary across MSI/INTx/etc. >> > I checked the code: IRQ_DISABLE is implemented in software, i.e. > handle_level_irq() only calls handle_IRQ_event() [and then the nic irq > handler] if IRQ_DISABLE is not set. > OTHO: The last trace looks as if nv_do_nic_poll() is interrupted by an irq. > > Perhaps something corrupts dev->irq? The irq is requested with > request_irq(np->pci_dev->irq, handler, IRQF_SHARED, dev->name, dev) > and disabled with > disable_irq_lockdep(dev->irq); > > Someone around with a MSI capable board? The forcedeth driver does > dev->irq = pci_dev->irq > in nv_probe(), especially before pci_enable_msi(). > Does pci_enable_msi() change pci_dev->irq? Then we would disable the > wrong interrupt.... Remember, fundamentally MSI-X is a one-to-many relationship, when you consider a single PCI device might have multiple vectors. Jeff