From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: Broken pci_block_user_cfg_access interface Date: Mon, 29 Aug 2011 20:47:07 +0200 Message-ID: <4E5BDEAB.5000405@siemens.com> References: <20110829150552.GA6851@redhat.com> <4E5BB358.3060705@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4E5BB358.3060705@siemens.com> Sender: linux-pci-owner@vger.kernel.org To: "Michael S. Tsirkin" Cc: Jesse Barnes , Brian King , "James E.J. Bottomley" , "Hans J. Koch" , Greg Kroah-Hartman , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, kvm@vger.kernel.org List-Id: linux-scsi@vger.kernel.org On 2011-08-29 17:42, Jan Kiszka wrote: > I still don't get what prevents converting ipr to allow plain mutex > synchronization. My vision is: > - push reset-on-error of ipr into workqueue (or threaded IRQ?) I'm starting to like your proposal: I had a look at ipr, but it turned out to be anything but trivial to convert that driver. It runs its complete state machine under spin_lock_irq, and the functions calling pci_block/unblock_user_cfg_access are deep inside this thing. I have no hardware to test whatever change, and I feel a bit uncomfortable asking Brian to redesign his driver that massively. So back to your idea: I would generalize pci_block_user_cfg_access to pci_block_cfg_access. It should fail when some other site already holds the access lock, but it should remain non-blocking - for the sake of ipr. We should still provide generic pci-2.3 IRQ masking services, but that could be done in a second step. I could have a look at this. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux