Re: [RFC v5 2/7] PCI: Do not Use IORESOURCE_STARTALIGN to identify bridge resources

From: Yongji Xie
Date: Tue Apr 05 2016 - 22:17:04 EST


On 2016/4/6 8:55, Gavin Shan wrote:
On Tue, Apr 05, 2016 at 09:43:30PM +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.

In this patch, we try to use a more robust way
to identify bridge resources.

Signed-off-by: Yongji Xie <xyjxie@xxxxxxxxxxxxxxxxxx>
---
drivers/pci/setup-bus.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 7796d0a..bffcf1e 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -391,6 +391,7 @@ 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))
@@ -411,11 +412,14 @@ 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 (pci_is_bridge(dev_res->dev) &&
+ index >= PCI_BRIDGE_RESOURCES &&
+ index <= PCI_BRIDGE_RESOURCE_END)
continue;
Yongji, the condition seems incorrect. According to the comments in
the code, it's resizing bridge's windows. So I think the code would
be something like below?

if (!pci_is_bridge(dev_res->dev) ||
index < PCI_BRIDGE_RESOURCES ||
index > PCI_BRIDGE_RESOURCE_END)
continue;

Yes. I made a mistake here. It should be something like
the above code.

Thanks,
Yongji

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

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