linux-kernel - Re: [PATCH] PCI/AER: Fix an AER enabling/disabling race

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Date:   Mon, 3 Sep 2018 19:32:47 +0000
From:   "Derrick, Jonathan" <jonathan.derrick@...el.com>
To:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "okaya@...nel.org" <okaya@...nel.org>,
        "willy@...radead.org" <willy@...radead.org>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "hch@....de" <hch@....de>,
        "helgaas@...nel.org" <helgaas@...nel.org>,
        "lukas@...ner.de" <lukas@...ner.de>,
        "mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>,
        "poza@...eaurora.org" <poza@...eaurora.org>,
        "Busch, Keith" <keith.busch@...el.com>
Subject: Re: [PATCH] PCI/AER: Fix an AER enabling/disabling race

Hi,

After giving this a few days thought, I think the right way is to call
pci_enable_pcie_error_reporting after portdrv probe, and prevent AER's
pci_walk_bus from enabling err reporting if the port hasn't been
probed.

I'm going to Self-NAK this and follow-up

Sorry for the noise

On Sat, 2018-09-01 at 19:06 -0600, Jon Derrick wrote:
> There is a sequence with non-ACPI root ports where the AER driver can
> enable error reporting on the tree before port drivers have bound to
> ports on the tree. The port driver assumes the AER driver will set up
> error reporting afterwards, so instead add a check if error reporting
> was set up first.
> 
> Example:
> [  343.790573] pcieport 10000:00:00.0:
> pci_disable_pcie_error_reporting
> [  343.809812] pcieport 10000:00:00.0:
> pci_enable_pcie_error_reporting
> [  343.819506] pci 10000:01:00.0: pci_enable_pcie_error_reporting
> [  343.828814] pci 10000:02:00.0: pci_enable_pcie_error_reporting
> [  343.838089] pci 10000:02:01.0: pci_enable_pcie_error_reporting
> [  343.847478] pci 10000:02:02.0: pci_enable_pcie_error_reporting
> [  343.856659] pci 10000:02:03.0: pci_enable_pcie_error_reporting
> [  343.865794] pci 10000:02:04.0: pci_enable_pcie_error_reporting
> [  343.874875] pci 10000:02:05.0: pci_enable_pcie_error_reporting
> [  343.883918] pci 10000:02:06.0: pci_enable_pcie_error_reporting
> [  343.892922] pci 10000:02:07.0: pci_enable_pcie_error_reporting
> [  343.918900] pcieport 10000:01:00.0:
> pci_disable_pcie_error_reporting
> [  343.968426] pcieport 10000:02:00.0:
> pci_disable_pcie_error_reporting
> [  344.028179] pcieport 10000:02:01.0:
> pci_disable_pcie_error_reporting
> [  344.091269] pcieport 10000:02:02.0:
> pci_disable_pcie_error_reporting
> [  344.156473] pcieport 10000:02:03.0:
> pci_disable_pcie_error_reporting
> [  344.238042] pcieport 10000:02:04.0:
> pci_disable_pcie_error_reporting
> [  344.321864] pcieport 10000:02:05.0:
> pci_disable_pcie_error_reporting
> [  344.411601] pcieport 10000:02:06.0:
> pci_disable_pcie_error_reporting
> [  344.505332] pcieport 10000:02:07.0:
> pci_disable_pcie_error_reporting
> [  344.621824] nvme 10000:06:00.0: pci_enable_pcie_error_reporting
> 
> Signed-off-by: Jon Derrick <jonathan.derrick@...el.com>
> ---
>  drivers/pci/pcie/aer.c          | 1 +
>  drivers/pci/pcie/portdrv_core.c | 5 ++++-
>  include/linux/pci.h             | 1 +
>  3 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index 83180ed..a4e36b6 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -1333,6 +1333,7 @@ static int set_device_error_reporting(struct
> pci_dev *dev, void *data)
>  	if (enable)
>  		pcie_set_ecrc_checking(dev);
>  
> +	dev->aer_configured = 1;
>  	return 0;
>  }
>  
> diff --git a/drivers/pci/pcie/portdrv_core.c
> b/drivers/pci/pcie/portdrv_core.c
> index 7c37d81..f5de554 100644
> --- a/drivers/pci/pcie/portdrv_core.c
> +++ b/drivers/pci/pcie/portdrv_core.c
> @@ -224,8 +224,11 @@ static int get_port_device_capability(struct
> pci_dev *dev)
>  		/*
>  		 * Disable AER on this port in case it's been
> enabled by the
>  		 * BIOS (the AER service driver will enable it when
> necessary).
> +		 * Don't disable it if the AER service driver has
> already
> +		 * enabled it from the root port bus walking
>  		 */
> -		pci_disable_pcie_error_reporting(dev);
> +		if (!dev->aer_configured)
> +			pci_disable_pcie_error_reporting(dev);
>  	}
>  #endif
>  
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index e72ca8d..c071622 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -402,6 +402,7 @@ struct pci_dev {
>  	unsigned int	has_secondary_link:1;
>  	unsigned int	non_compliant_bars:1;	/* Broken
> BARs; ignore them */
>  	unsigned int	is_probed:1;		/* Device
> probing in progress */
> +	unsigned int	aer_configured:1;	/* AER
> configured for device */
>  	pci_dev_flags_t dev_flags;
>  	atomic_t	enable_cnt;	/* pci_enable_device has
> been called */
>  
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