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Date: Tue, 21 Jun 2016 10:59:51 +0800 From: Yongji Xie <xyjxie@...ux.vnet.ibm.com> To: Bjorn Helgaas <helgaas@...nel.org> Cc: nikunj@...ux.vnet.ibm.com, zhong@...ux.vnet.ibm.com, linux-doc@...r.kernel.org, aik@...abs.ru, linux-pci@...r.kernel.org, corbet@....net, linux-kernel@...r.kernel.org, gwshan@...ux.vnet.ibm.com, warrier@...ux.vnet.ibm.com, alex.williamson@...hat.com, paulus@...ba.org, bhelgaas@...gle.com, linuxppc-dev@...ts.ozlabs.org Subject: Re: [RESEND PATCH v2 2/4] PCI: Do not Use IORESOURCE_STARTALIGN to identify bridge resources On 2016/6/21 9:50, Bjorn Helgaas wrote: > On Thu, Jun 02, 2016 at 01:46:49PM +0800, Yongji Xie wrote: >> Now we use the IORESOURCE_STARTALIGN to identify bridge resources >> in __assign_resources_sorted(). That's quite fragile. We can't >> make sure that the PCI devices' resources will not use >> IORESOURCE_STARTALIGN any more. > Can you explain this a little more? I don't quite understand the > problem. Maybe you can give an example of the problem? Now there are two kinds of additional resources in the list: bridge resource and SR-IOV resource. Here we just want to fix the additional alignment for bridge. But if SR-IOV resource get the flag IORESOURCE_STARTALIGN which is not only for bridge, the current check seems to be wrong. And kernel parameter "resource_alignment" could set IORESOURCE_STARTALIGN for SR-IOV resource with my next patch applied. Thanks, Yongji >> In this patch, we try to use a more robust way to identify >> bridge resources. >> >> Signed-off-by: Yongji Xie <xyjxie@...ux.vnet.ibm.com> >> --- >> drivers/pci/setup-bus.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c >> index 55641a3..216ddbc 100644 >> --- a/drivers/pci/setup-bus.c >> +++ b/drivers/pci/setup-bus.c >> @@ -390,6 +390,7 @@ static void __assign_resources_sorted(struct list_head *head, >> struct pci_dev_resource *dev_res, *tmp_res, *dev_res2; >> unsigned long fail_type; >> resource_size_t add_align, align; >> + int index; >> >> /* Check if optional add_size is there */ >> if (!realloc_head || list_empty(realloc_head)) >> @@ -410,11 +411,13 @@ static void __assign_resources_sorted(struct list_head *head, >> >> /* >> * There are two kinds of additional resources in the list: >> - * 1. bridge resource -- IORESOURCE_STARTALIGN >> - * 2. SR-IOV resource -- IORESOURCE_SIZEALIGN >> + * 1. bridge resource >> + * 2. SR-IOV resource >> * Here just fix the additional alignment for bridge >> */ >> - if (!(dev_res->res->flags & IORESOURCE_STARTALIGN)) >> + index = dev_res->res - dev_res->dev->resource; >> + if (index < PCI_BRIDGE_RESOURCES || >> + index > PCI_BRIDGE_RESOURCE_END) > I think the code looks OK; at least, it seems to match the comment. > I'd just like to understand the problem a little better. > >> continue; >> >> add_align = get_res_add_align(realloc_head, dev_res->res); >> -- >> 1.7.9.5 >> > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@...ts.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev
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