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Message-ID: <56330771.90509@oracle.com> Date: Fri, 30 Oct 2015 14:00:17 +0800 From: ethan zhao <ethan.zhao@...cle.com> To: Wei Yang <weiyang@...ux.vnet.ibm.com>, Bjorn Helgaas <bhelgaas@...gle.com> CC: Alexander Duyck <aduyck@...antis.com>, linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v2 5/7] PCI: Wait 1 second between disabling VFs and clearing NumVFs 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 <aduyck@...antis.com> >> >> 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 <aduyck@...antis.com> >> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com> >> --- >> 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; >> } >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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