linux-kernel - Re: [PATCH] PCI/portdrv: Enable error reporting on managed ports

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Message-ID: <20181011151610.GM5906@bhelgaas-glaptop.roam.corp.google.com>
Date:   Thu, 11 Oct 2018 10:16:10 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Dongdong Liu <liudongdong3@...wei.com>
Cc:     "Derrick, Jonathan" <jonathan.derrick@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "okaya@...nel.org" <okaya@...nel.org>,
        "willy@...radead.org" <willy@...radead.org>,
        "hch@....de" <hch@....de>, "lukas@...ner.de" <lukas@...ner.de>,
        "mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>,
        "poza@...eaurora.org" <poza@...eaurora.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "Busch, Keith" <keith.busch@...el.com>
Subject: Re: [PATCH] PCI/portdrv: Enable error reporting on managed ports

On Thu, Oct 11, 2018 at 07:58:47PM +0800, Dongdong Liu wrote:
> Hi Bjorn
> 
> > commit 15a6711649915ca3e9d1086dc88ff4b616b99aac
> > Author: Bjorn Helgaas <bhelgaas@...gle.com>
> > Date:   Tue Oct 9 17:25:25 2018 -0500
> > 
> >     PCI/AER: Enable reporting for ports enumerated after AER driver registration
> > 
> >     Previously we enabled AER error reporting only for Switch Ports that were
> >     enumerated prior to registering the AER service driver.  Switch Ports
> >     enumerated after AER driver registration were left with error reporting
> >     disabled.
> > 
> >     A common order, which works correctly, is that we enumerate devices before
> >     registering portdrv and the AER driver:
> > 
> >       - Enumerate all the devices at boot-time
> > 
> >       - Register portdrv and bind it to all Root Ports and Switch Ports, which
> >         disables error reporting for these Ports
> > 
> >       - Register AER service driver and bind it to all Root Ports, which
> >         enables error reporting for the Root Ports and any Switch Ports below
> >         them
> > 
> >     But if we enumerate devices *after* registering portdrv and the AER driver,
> >     e.g., if a host bridge driver is loaded as a module, error reporting is not
> >     enabled correctly:
> > 
> >       - Register portdrv and AER driver (this happens at boot-time)
> > 
> >       - Enumerate a Root Port
> > 
> >       - Bind portdrv to Root Port, disabling its error reporting
> > 
> >       - Bind AER service driver to Root Port, enabling error reporting for it
> >         and its children (none, since we haven't enumerated them yet)
> > 
> >       - Enumerate Switch Port below the Root Port
> > 
> >       - Bind portdrv to Switch Port, disabling its error reporting
> > 
> >       - AER service driver doesn't bind to Switch Ports, so error reporting
> >         remains disabled
> > 
> >     Hot-adding a Switch fails similarly: error reporting is enabled correctly
> >     for the Root Port, but when the Switch is enumerated, the AER service
> >     driver doesn't claim it, so there's nothing to enable error reporting for
> >     the Switch Ports.
> > 
> >     Change the AER service driver so it binds to *all* PCIe ports, including
> >     Switch Upstream and Downstream Ports.  For Switch Ports, enable AER error
> >     reporting.
> > 
> >     Link: https://lore.kernel.org/linux-pci/1536085989-2956-1-git-send-email-jonathan.derrick@intel.com
> >     Based-on-patch-by: Jon Derrick <jonathan.derrick@...el.com>
> >     Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> > 
> > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> > index 90b53abf621d..fe6c16461367 100644
> > --- a/drivers/pci/pcie/aer.c
> > +++ b/drivers/pci/pcie/aer.c
> > @@ -1316,12 +1316,6 @@ static void aer_enable_rootport(struct aer_rpc *rpc)
> >  	pci_read_config_dword(pdev, aer_pos + PCI_ERR_UNCOR_STATUS, &reg32);
> >  	pci_write_config_dword(pdev, aer_pos + PCI_ERR_UNCOR_STATUS, reg32);
> > 
> > -	/*
> > -	 * Enable error reporting for the root port device and downstream port
> > -	 * devices.
> > -	 */
> > -	set_downstream_devices_error_reporting(pdev, true);
> > -
> 
> Delete the code will also disable error reporting for the root port as
> the portdrv to Root Port has disabled its error reporting,
> so need to enable enable error reporting for the root port.
> +pci_enable_pcie_error_reporting(pdev);

Oh, you're right, thank you!

I'll post a "v3" to fix this, i.e.,

  v1 - Jon's original post, https://lore.kernel.org/linux-pci/1536085989-2956-1-git-send-email-jonathan.derrick@intel.com
  v2 - My rework, https://lore.kernel.org/linux-pci/20181009231915.GC5906@bhelgaas-glaptop.roam.corp.google.com
  v3 - My rework + enable error reporting for Root Ports

Bjorn