linux-kernel - Re: [PATCH v2 2/7] PCI: Remove redundant validation of SR-IOV offset/stride registers

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Date:	Fri, 30 Oct 2015 13:08:25 +0800
From:	Wei Yang <weiyang@...ux.vnet.ibm.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Alexander Duyck <aduyck@...antis.com>, linux-pci@...r.kernel.org,
	Ethan Zhao <ethan.zhao@...cle.com>,
	Wei Yang <weiyang@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/7] PCI: Remove redundant validation of SR-IOV
 offset/stride registers

On Thu, Oct 29, 2015 at 05:23:01PM -0500, Bjorn Helgaas wrote:
>From: Alexander Duyck <aduyck@...antis.com>
>
>Previously, we read, validated, and cached PCI_SRIOV_VF_OFFSET and
>PCI_SRIOV_VF_STRIDE in sriov_enable().  But sriov_init() now does
>that via compute_max_vf_buses(), so we don't need to do it again.
>
>Remove the PCI_SRIOV_VF_OFFSET and PCI_SRIOV_VF_STRIDE config reads from
>sriov_enable().  The pci_sriov structure already contains the offset and
>stride corresponding to the current NumVFs.
>
>[bhelgaas: split to separate patch for reviewability]
>Signed-off-by: Alexander Duyck <aduyck@...antis.com>
>Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>

Reviewed-by: Wei Yang <weiyang@...ux.vnet.ibm.com>

>---
> drivers/pci/iov.c |   10 +---------
> 1 file changed, 1 insertion(+), 9 deletions(-)
>
>diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
>index 1b1acc2..ca400a9 100644
>--- a/drivers/pci/iov.c
>+++ b/drivers/pci/iov.c
>@@ -235,7 +235,7 @@ 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;
>@@ -258,11 +258,6 @@ 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))
>-		return -EIO;
>-
> 	nres = 0;
> 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
> 		bars |= (1 << (i + PCI_IOV_RESOURCES));
>@@ -275,9 +270,6 @@ 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",

-- 
Richard Yang
Help you, Help me

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