linux-kernel - Re: [PATCH] PCI: fix link retrain status in pcie_wait_for_link

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Message-ID: <53b2239b-4a23-a948-a422-4005cbf76148@linux.intel.com>
Date: Wed, 13 Mar 2024 14:00:21 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Simon Guinot <simon.guinot@...gate.com>, 
    Bjorn Helgaas <bhelgaas@...gle.com>
cc: "Maciej W . Rozycki" <macro@...am.me.uk>, linux-pci@...r.kernel.org, 
    LKML <linux-kernel@...r.kernel.org>, stable@...r.kernel.org
Subject: Re: [PATCH] PCI: fix link retrain status in
 pcie_wait_for_link_delay()

On Wed, 13 Mar 2024, Simon Guinot wrote:

> The current code in pcie_wait_for_link_delay() handles the value
> returned by pcie_failed_link_retrain() as an integer, expecting 0
> when the link has been successfully retrained. The issue is that
> pcie_failed_link_retrain() returns a boolean: "true" if the link
> has been successfully retrained and "false" otherwise. This leads
> pcie_wait_for_link_delay() to return an incorrect "active link"
> status when pcie_failed_link_retrain() is called.
> 
> This patch fixes the check of the value returned by
> pcie_failed_link_retrain() in pcie_wait_for_link_delay().
> 
> Note that this bug induces abnormal timeout delays when a PCI device
> is unplugged (around 60 seconds per bridge / secondary bus removed).
> 
> Cc: stable@...r.kernel.org
> Fixes: 1abb47390350 ("Merge branch 'pci/enumeration'")
> Signed-off-by: Simon Guinot <simon.guinot@...gate.com>

Hi Simon,

Thanks for your patch. There's, however, already a better series to fix 
this and other related issues. Bjorn just hasn't gotten into applying them 
yet:

https://patchwork.kernel.org/project/linux-pci/list/?series=824858

(I proposed a patch very similar to yours month ago, but Maciej came up 
a better way to fix all the issues.)

--
 i.

> ---
>  drivers/pci/pci.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index ccee56615f78..7ec91b4c5d03 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5101,9 +5101,7 @@ static bool pcie_wait_for_link_delay(struct pci_dev *pdev, bool active,
>  		msleep(20);
>  	rc = pcie_wait_for_link_status(pdev, false, active);
>  	if (active) {
> -		if (rc)
> -			rc = pcie_failed_link_retrain(pdev);
> -		if (rc)
> +		if (rc && !pcie_failed_link_retrain(pdev))
>  			return false;
>  
>  		msleep(delay);
> 

-- 
 i.