From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:39628 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751219AbbJ3GA1 (ORCPT ); Fri, 30 Oct 2015 02:00:27 -0400 Message-ID: <56330771.90509@oracle.com> Date: Fri, 30 Oct 2015 14:00:17 +0800 From: ethan zhao MIME-Version: 1.0 To: Wei Yang , Bjorn Helgaas CC: Alexander Duyck , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 5/7] PCI: Wait 1 second between disabling VFs and clearing NumVFs References: <20151029221701.11908.82718.stgit@bhelgaas-glaptop2.roam.corp.google.com> <20151029222322.11908.13738.stgit@bhelgaas-glaptop2.roam.corp.google.com> <20151030051458.GD5119@richards-mbp.cn.ibm.com> In-Reply-To: <20151030051458.GD5119@richards-mbp.cn.ibm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-pci-owner@vger.kernel.org List-ID: Wei, On 2015/10/30 13:14, Wei Yang wrote: > On Thu, Oct 29, 2015 at 05:23:22PM -0500, Bjorn Helgaas wrote: >> From: Alexander Duyck >> >> Per sec 3.3.3.1 of the SR-IOV spec, r1.1, we must allow 1.0s after clearing >> VF Enable before reading any field in the SR-IOV Extended Capability. >> >> Wait 1 second before calling pci_iov_set_numvfs(), which reads >> PCI_SRIOV_VF_OFFSET and PCI_SRIOV_VF_STRIDE after it sets PCI_SRIOV_NUM_VF. >> >> [bhelgaas: split to separate patch for reviewability, add spec reference] >> Signed-off-by: Alexander Duyck >> Signed-off-by: Bjorn Helgaas >> --- >> drivers/pci/iov.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c >> index fada98d..24428d5 100644 >> --- a/drivers/pci/iov.c >> +++ b/drivers/pci/iov.c >> @@ -339,13 +339,13 @@ failed: >> iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE); >> pci_cfg_access_lock(dev); >> pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl); >> - pci_iov_set_numvfs(dev, 0); >> ssleep(1); >> pci_cfg_access_unlock(dev); >> >> if (iov->link != dev->devfn) >> sysfs_remove_link(&dev->dev.kobj, "dep_link"); >> >> + pci_iov_set_numvfs(dev, 0); > One small question, any specific reason put it here instead of just after > sleep()? Agree, pci_iov_set_numvfs(dev, 0) should be put before pci_cfg_access_unlock(dev) to avoid race, because "NumVFs may only be written while VF Enable is Clear" Thanks, Ethan >> return rc; >> } >>