linux-kernel - Re: [PATCH v12 05/15] PCI/ERR: Simplify by using pci_upstream

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Date:   Thu, 3 Dec 2020 18:45:00 +0000
From:   "Kelley, Sean V" <sean.v.kelley@...el.com>
To:     "bhelgaas@...gle.com" <bhelgaas@...gle.com>
CC:     Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        "xerces.zhao@...il.com" <xerces.zhao@...il.com>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "Kuppuswamy, Sathyanarayanan" <sathyanarayanan.kuppuswamy@...el.com>,
        "Zhuo, Qiuxu" <qiuxu.zhuo@...el.com>,
        Linux PCI <linux-pci@...r.kernel.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        "Kuppuswamy Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Subject: Re: [PATCH v12 05/15] PCI/ERR: Simplify by using
 pci_upstream_bridge()


Hi Bjorn,

Just confirming that when switched from dev->bus->self to pci_upstream_bridge() we’re okay with the NULL case:

> On Nov 20, 2020, at 4:10 PM, Sean V Kelley <sean.v.kelley@...el.com> wrote:
> 
> Use pci_upstream_bridge() in place of dev->bus->self.  No functional change
> intended.
> 
> [bhelgaas: split to separate patch]
> Link: https://lore.kernel.org/r/20201002184735.1229220-6-seanvk.dev@oregontracks.org
> Signed-off-by: Sean V Kelley <sean.v.kelley@...el.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> Acked-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> ---
> drivers/pci/pcie/err.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> index db149c6ce4fb..05f61da5ed9d 100644
> --- a/drivers/pci/pcie/err.c
> +++ b/drivers/pci/pcie/err.c
> @@ -159,7 +159,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> 	 */
> 	if (!(pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
> 	      pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM))
> -		dev = dev->bus->self;
> +		dev = pci_upstream_bridge(dev);


The only case where pci_upstream_bridge(dev) could be NULL is if dev->bus is the root bus and we are being
selective based on the type.

Even later in this series when we actually add in RC_EC/RC_END we maintain the conditional checks:

https://lore.kernel.org/linux-pci/20201121001036.8560-11-sean.v.kelley@intel.com/

 pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,

@@ -174,10 +180,13 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,

 
 	/*
 	 * Error recovery runs on all subordinates of the bridge.  If the
-	 * bridge detected the error, it is cleared at the end.
+	 * bridge detected the error, it is cleared at the end.  For RCiEPs
+	 * we should reset just the RCiEP itself.

 	 */
 	if (type == PCI_EXP_TYPE_ROOT_PORT ||
-	    type == PCI_EXP_TYPE_DOWNSTREAM)
+	    type == PCI_EXP_TYPE_DOWNSTREAM ||
+	    type == PCI_EXP_TYPE_RC_EC ||
+	    type == PCI_EXP_TYPE_RC_END)
 		bridge = dev;
 	else
 		bridge = pci_upstream_bridge(dev);

I believe we are okay here.

Sean


> 	bus = dev->subordinate;
> 
> 	pci_dbg(dev, "broadcast error_detected message\n");
> -- 
> 2.29.2
> 
>