linux-kernel - Re: [PATCH 2/2] PCI/AER: Try slot reset before secondary bus reset

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Date:   Fri, 27 Apr 2018 14:51:24 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     linux-pci@...r.kernel.org, sulrich@...eaurora.org,
        timur@...eaurora.org
Cc:     linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Frederick Lawler <fred@...dlawl.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Juan J. Alvarez" <jjalvare@...ux.vnet.ibm.com>,
        Russell Currey <ruscur@...sell.cc>,
        Gabriele Paoloni <gabriele.paoloni@...wei.com>,
        Keith Busch <keith.busch@...el.com>,
        Tyler Baicar <tbaicar@...eaurora.org>,
        "Bryant G. Ly" <bryantly@...ux.vnet.ibm.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] PCI/AER: Try slot reset before secondary bus reset

Hi Bjorn,

On 4/19/2018 3:56 PM, Sinan Kaya wrote:
> The endpoint observing AER_FATAL error might be connected to a PCI hotplug
> slot. Performing secondary bus reset on a hotplug slot causes PCI link
> up/down interrupts.
> 
> Hotplug driver removes the device from system when a link down interrupt
> is observed and performs re-enumeration when link up interrupt is observed.
> 
> This conflicts with what this code is trying to do. Try secondary bus
> reset only if pci_reset_slot() fails/unsupported.
> 
> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> ---
>  drivers/pci/pcie/aer/aerdrv.c      | 3 ++-
>  drivers/pci/pcie/aer/aerdrv_core.c | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pcie/aer/aerdrv.c b/drivers/pci/pcie/aer/aerdrv.c
> index 779b387..4eaa524 100644
> --- a/drivers/pci/pcie/aer/aerdrv.c
> +++ b/drivers/pci/pcie/aer/aerdrv.c
> @@ -318,7 +318,8 @@ static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
>  	reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK;
>  	pci_write_config_dword(dev, pos + PCI_ERR_ROOT_COMMAND, reg32);
>  
> -	pci_reset_bridge_secondary_bus(dev);
> +	if (pci_reset_slot(dev->slot))
> +		pci_reset_bridge_secondary_bus(dev);
>  	pci_printk(KERN_DEBUG, dev, "Root Port link has been reset\n");
>  
>  	/* Clear Root Error Status */
> diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
> index 0ea5acc..a915b0e6 100644
> --- a/drivers/pci/pcie/aer/aerdrv_core.c
> +++ b/drivers/pci/pcie/aer/aerdrv_core.c
> @@ -407,7 +407,8 @@ static pci_ers_result_t broadcast_error_message(struct pci_dev *dev,
>   */
>  static pci_ers_result_t default_reset_link(struct pci_dev *dev)
>  {
> -	pci_reset_bridge_secondary_bus(dev);
> +	if (pci_reset_slot(dev->slot))
> +		pci_reset_bridge_secondary_bus(dev);
>  	pci_printk(KERN_DEBUG, dev, "downstream link has been reset\n");
>  	return PCI_ERS_RESULT_RECOVERED;
>  }
> 

If we put the 1/2 patch aside, what do you think about pulling this for 4.18?

Sinan

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.