From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0DB5C28CC0 for ; Thu, 30 May 2019 14:33:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9345325250 for ; Thu, 30 May 2019 14:33:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726439AbfE3Odm (ORCPT ); Thu, 30 May 2019 10:33:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48496 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726250AbfE3Odl (ORCPT ); Thu, 30 May 2019 10:33:41 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8DBEB7EBAE; Thu, 30 May 2019 14:33:41 +0000 (UTC) Received: from x1.home (ovpn-116-22.phx2.redhat.com [10.3.116.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2E90310027B6; Thu, 30 May 2019 14:33:36 +0000 (UTC) Date: Thu, 30 May 2019 08:33:35 -0600 From: Alex Williamson To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, myron.stowe@redhat.com, bodong@mellanox.com, eli@mellanox.com, laine@redhat.com Subject: Re: [PATCH] PCI: Return error if cannot probe VF Message-ID: <20190530083335.4f16a9bc@x1.home> In-Reply-To: <20190530134727.GM28250@google.com> References: <155672991496.20698.4279330795743262888.stgit@gimli.home> <20190530134727.GM28250@google.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Thu, 30 May 2019 14:33:41 +0000 (UTC) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, 30 May 2019 08:47:27 -0500 Bjorn Helgaas wrote: > On Wed, May 01, 2019 at 11:00:16AM -0600, Alex Williamson wrote: > > Commit 0e7df22401a3 ("PCI: Add sysfs sriov_drivers_autoprobe to control > > VF driver binding") allows the user to specify that drivers for VFs of > > a PF should not be probed, but it actually causes pci_device_probe() to > > return success back to the driver core in this case. Therefore by all > > sysfs appearances the device is bound to a driver, the driver link from > > the device exists as does the device link back from the driver, yet the > > driver's probe function is never called on the device. We also fail to > > do any sort of cleanup when we're prohibited from probing the device, > > the irq setup remains in place and we even hold a device reference. > > > > Instead, abort with errno before any setup or references are taken when > > pci_device_can_probe() prevents us from trying to probe the device. > > > > Fixes: 0e7df22401a3 ("PCI: Add sysfs sriov_drivers_autoprobe to control VF driver binding") > > Signed-off-by: Alex Williamson > > Applied to pci/enumeration for v5.3, thanks! > > The scenario you describe, Laine, indeed sounds cumbersome. If you > want to propose an alternate or additional patch to address that, or > if you think Alex's patch will make it harder to clean up that > scenario, I'm all ears. But it seems like Alex's patch is an > improvement even if it leaves some problems unsolved. Hi Bjorn, It's probably deeper in your queue, but I've posted: https://patchwork.kernel.org/patch/10937577/ which allows devices with a driver_override to always probe. I think it gives us the more desirable usage model. Thanks, Alex > > --- > > > > This issue is easily tested by disabling sriov_drivers_autoprobe and > > creating VFs: > > > > # echo 0 > sriov_drivers_autoprobe > > # echo 3 > sriov_numvfs > > # readlink -f virtfn*/driver > > /sys/bus/pci/drivers/iavf > > /sys/bus/pci/drivers/iavf > > /sys/bus/pci/drivers/iavf > > (yet no netdevs exist for these VFs) > > > > The semantics of this autoprobe disabling are a bit strange for the > > user as well, I suppose it works if we force a bind through a driver's > > bind attribute, but tools like libvirt and driverctl expect to bind > > devices by setting the driver_override and then pushing the device > > through driver_probe on the bus. Is the intention of disabling > > "autoprobe" that a driver_override should still work? Otherwise the > > user needs to set the driver_override for each VF, re-enable > > sriov_drivers_autoprobe on the PF, and then probe the VFs. Thus maybe > > pci_device_can_probe() should allow probes of the driver_override > > driver? Thanks, > > > > Alex > > > > drivers/pci/pci-driver.c | 13 +++++++------ > > 1 file changed, 7 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c > > index 71853befd435..da7b82e56c83 100644 > > --- a/drivers/pci/pci-driver.c > > +++ b/drivers/pci/pci-driver.c > > @@ -414,6 +414,9 @@ static int pci_device_probe(struct device *dev) > > struct pci_dev *pci_dev = to_pci_dev(dev); > > struct pci_driver *drv = to_pci_driver(dev->driver); > > > > + if (!pci_device_can_probe(pci_dev)) > > + return -ENODEV; > > + > > pci_assign_irq(pci_dev); > > > > error = pcibios_alloc_irq(pci_dev); > > @@ -421,12 +424,10 @@ static int pci_device_probe(struct device *dev) > > return error; > > > > pci_dev_get(pci_dev); > > - if (pci_device_can_probe(pci_dev)) { > > - error = __pci_device_probe(drv, pci_dev); > > - if (error) { > > - pcibios_free_irq(pci_dev); > > - pci_dev_put(pci_dev); > > - } > > + error = __pci_device_probe(drv, pci_dev); > > + if (error) { > > + pcibios_free_irq(pci_dev); > > + pci_dev_put(pci_dev); > > } > > > > return error; > >