linux-kernel - Re: [PATCH v3 5/7] PCI: Do not use IORESOURCE

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Message-Id: <20160701023423.GB6739@gwshan>
Date:	Fri, 1 Jul 2016 12:34:23 +1000
From:	Gavin Shan <gwshan@...ux.vnet.ibm.com>
To:	Yongji Xie <xyjxie@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-doc@...r.kernel.org,
	bhelgaas@...gle.com, alex.williamson@...hat.com, aik@...abs.ru,
	benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au,
	corbet@....net, warrier@...ux.vnet.ibm.com,
	zhong@...ux.vnet.ibm.com, nikunj@...ux.vnet.ibm.com,
	gwshan@...ux.vnet.ibm.com
Subject: Re: [PATCH v3 5/7] PCI: Do not use IORESOURCE_STARTALIGN to identify
 bridge resources

On Thu, Jun 30, 2016 at 06:53:11PM +0800, Yongji Xie wrote:
>Now we use the IORESOURCE_STARTALIGN to identify bridge resources
>in __assign_resources_sorted(). That's quite fragile. We may also
>set flag IORESOURCE_STARTALIGN for SR-IOV resources in some cases,
>for example, using the option "noresize" of parameter
>"pci=resource_alignment".
>
>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>

Reviewed-by: Gavin Shan <gwshan@...ux.vnet.ibm.com>

Yongji, I think this doesn't have to be part of this series, meaning
it can be sent or merged separately.

>---
> 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)
> 			continue;
>
> 		add_align = get_res_add_align(realloc_head, dev_res->res);

Thanks,
Gavin