On Wed, Sep 9, 2015 at 4:32 AM, Lorenzo Pieralisi
<lorenzo.pieralisi@xxxxxxx> wrote:
> Subject: [PATCH] PCI: remove dead code in pci_claim_bridge_resource()
>
> Commit 8505e729a2f6eb ("PCI: Add pci_claim_bridge_resource() to clip
> window if necessary") introduced a new API to claim bridge resources.
>
> pci_claim_bridge_resource() tries to claim a bridge resource, and if
> the claiming fails the function tries to clip the resource to make
> it fit within the parent resource window.
>
> If the clipping succeeds the bridge apertures are set-up accordingly
> and the pci_claim_bridge_resource() tries to claim the resource
> again.
>
> Commit c770cb4cb505 ("PCI: Mark invalid BARs as unassigned") added
> code that sets the IORESOURCE_UNSET flag on claiming failure.
>
> This means that the second resource claiming after window clipping will
> always fail, since the resource flags contain IORESOURCE_UNSET,
> previously set on failure by pci_claim_resource(), so the subsequent
> pci_claim_resource() call ends up spitting a log message and return
> failure with no chance whatsoever to succeed.
>
> This patch removes the second pci_claim_resource() call in
> pci_claim_bridge_resource() since it basically has no chance to
> succeed, leaving the current behaviour unchanged.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
> ---
> drivers/pci/setup-bus.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 508cc56..2bf4ac1 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -728,14 +728,10 @@ int pci_claim_bridge_resource(struct pci_dev *bridge, int i)
> break;
> case 2:
> pci_setup_bridge_mmio_pref(bridge);
> - break;
> default:
> - return -EINVAL;
> + break;
> }
>
> - if (pci_claim_resource(bridge, i) == 0)
> - return 0; /* claimed a smaller window */
> -
> return -EINVAL;
> }
That should be regression from c770cb4cb505 ("PCI: Mark invalid BARs
as unassigned")
so right fix should be:
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 508cc56..76b3349 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -733,6 +733,7 @@ int pci_claim_bridge_resource(struct pci_dev *bridge, int i)
return -EINVAL;
}
+ bridge->resource[i].flags &= ~IORESOURCE_UNSET;
if (pci_claim_resource(bridge, i) == 0)
return 0; /* claimed a smaller window */
--
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