linux-kernel - Re: [PATCH 1/2] IB/hfi1: Try slot reset before secondary bus reset

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Date:   Thu, 19 Apr 2018 14:26:32 -0600
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Sinan Kaya <okaya@...eaurora.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     linux-pci@...r.kernel.org, sulrich@...eaurora.org,
        timur@...eaurora.org, linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Mike Marciniszyn <mike.marciniszyn@...el.com>,
        Dennis Dalessandro <dennis.dalessandro@...el.com>,
        Doug Ledford <dledford@...hat.com>,
        "open list:HFI1 DRIVER" <linux-rdma@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] IB/hfi1: Try slot reset before secondary bus reset

On Thu, Apr 19, 2018 at 03:56:23PM -0400, Sinan Kaya wrote:
> The infiniband adapter 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/infiniband/hw/hfi1/pcie.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/hw/hfi1/pcie.c b/drivers/infiniband/hw/hfi1/pcie.c
> index 83d66e8..75f49e3 100644
> +++ b/drivers/infiniband/hw/hfi1/pcie.c
> @@ -908,7 +908,8 @@ static int trigger_sbr(struct hfi1_devdata *dd)

The code above this hunk is:

/*
 * Trigger a secondary bus reset (SBR) on ourselves using our parent.
 *
 * Based on pci_parent_bus_reset() which is not exported by the
 * kernel core.
 */
static int trigger_sbr(struct hfi1_devdata *dd)
{

[..]

This really seems like something the PCI core should be helping with,
drivers shouldn't be doing stuff like this. I get the feeling this
should be a common need if drivers support various error recovery
schemes?

Bjorn, would be appropriate to export pci_parent_bus_reset() or some
variation therin??

Thanks,
Jason