From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.136]:53812 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758150AbbJVS4v (ORCPT ); Thu, 22 Oct 2015 14:56:51 -0400 Date: Thu, 22 Oct 2015 13:56:47 -0500 From: Bjorn Helgaas To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, Ben Shelton , linux-kernel@vger.kernel.org, Alexander Duyck Subject: Re: [PATCH] PCI: Remove unnecessary re-read of SR-IOV offset/stride registers Message-ID: <20151022185647.GF21237@localhost> References: <20151016211628.31492.86258.stgit@bhelgaas-glaptop2.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20151016211628.31492.86258.stgit@bhelgaas-glaptop2.roam.corp.google.com> Sender: linux-pci-owner@vger.kernel.org List-ID: On Fri, Oct 16, 2015 at 04:16:28PM -0500, Bjorn Helgaas wrote: > Previously, we read PCI_SRIOV_VF_OFFSET and PCI_SRIOV_VF_STRIDE from the > SR-IOV capability in pci_iov_set_numvfs() after changing PCI_SRIOV_NUM_VF, > and we read them again in sriov_enable(). But sriov_init() always calls > pci_iov_set_numvfs() before a successful return, and it caches the offset > and stride values, so there's no need to read the capability again in > sriov_enable(). > > Remove the PCI_SRIOV_VF_OFFSET and PCI_SRIOV_VF_STRIDE config reads from > sriov_enable() and use the cached values from the pci_sriov structure. > > Signed-off-by: Bjorn Helgaas I haven't seen any objections, so I applied this to pci/virtualization for v4.4. > --- > drivers/pci/iov.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) > > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c > index 0202ab0..9b52ad4 100644 > --- a/drivers/pci/iov.c > +++ b/drivers/pci/iov.c > @@ -230,7 +230,7 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn) > int rc; > int i, j; > int nres; > - u16 offset, stride, initial; > + u16 initial; > struct resource *res; > struct pci_dev *pdev; > struct pci_sriov *iov = dev->sriov; > @@ -253,9 +253,7 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn) > (!(iov->cap & PCI_SRIOV_CAP_VFM) && (nr_virtfn > initial))) > return -EINVAL; > > - pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_OFFSET, &offset); > - pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_STRIDE, &stride); > - if (!offset || (nr_virtfn > 1 && !stride)) > + if (!iov->offset || (nr_virtfn > 1 && !iov->stride)) > return -EIO; > > nres = 0; > @@ -270,9 +268,6 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn) > return -ENOMEM; > } > > - iov->offset = offset; > - iov->stride = stride; > - > bus = pci_iov_virtfn_bus(dev, nr_virtfn - 1); > if (bus > dev->bus->busn_res.end) { > dev_err(&dev->dev, "can't enable %d VFs (bus %02x out of range of %pR)\n", > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html