linux-kernel - Re: [PATCH] PCI: rework error checking in the reset path

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Date:   Wed, 25 Oct 2017 08:45:11 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Sinan Kaya <okaya@...eaurora.org>
Cc:     linux-pci@...r.kernel.org, timur@...eaurora.org,
        linux-arm-msm@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Alex Williamson <alex.williamson@...hat.com>
Subject: Re: [PATCH] PCI: rework error checking in the reset path

[+cc Alex]

On Mon, Oct 23, 2017 at 05:36:48PM -0400, Sinan Kaya wrote:
> The return codes from various reset types are not consistent. The code is
> assuming that all reset types will return -ENOTTY when things go wrong.
> Instead of relying on negative error status, let's bail out if the
> operation is successful instead.

I like this (no surprise since I suggested something similar at
http://lkml.kernel.org/r/20171011210057.GU25517@bhelgaas-glaptop.roam.corp.google.com),
but I'd like Alex's opinion before merging it.

Previously, we only tried the next reset method if one method failed
with -ENOTTY.  With this patch, we'll try the next reset method if one
method fails for any reason, not just -ENOTTY.

> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> ---
>  drivers/pci/pci.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 6078dfc..a753e07 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4200,20 +4200,20 @@ int __pci_reset_function_locked(struct pci_dev *dev)
>  	might_sleep();
>  
>  	rc = pci_dev_specific_reset(dev, 0);
> -	if (rc != -ENOTTY)
> +	if (!rc)
>  		return rc;
>  	if (pcie_has_flr(dev)) {
>  		pcie_flr(dev);
>  		return 0;
>  	}
>  	rc = pci_af_flr(dev, 0);
> -	if (rc != -ENOTTY)
> +	if (!rc)
>  		return rc;
>  	rc = pci_pm_reset(dev, 0);
> -	if (rc != -ENOTTY)
> +	if (!rc)
>  		return rc;
>  	rc = pci_dev_reset_slot_function(dev, 0);
> -	if (rc != -ENOTTY)
> +	if (!rc)
>  		return rc;
>  	return pci_parent_bus_reset(dev, 0);
>  }
> -- 
> 1.9.1
> 
> 
> _______________________________________________
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> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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