[PATCH] PCI: fix link retrain status in pcie_wait_for_link_delay()

[PATCH] PCI: fix link retrain status in pcie_wait_for_link_delay()

[Simon Guinot]

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@vger.kernel.org
Fixes: 1abb47390350 ("Merge branch 'pci/enumeration'")
Signed-off-by: Simon Guinot <simon.guinot@seagate.com>
---
 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);
-- 
2.43.0

Re: [PATCH] PCI: fix link retrain status in pcie_wait_for_link_delay()

[Ilpo Järvinen]

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@vger.kernel.org
> Fixes: 1abb47390350 ("Merge branch 'pci/enumeration'")
> Signed-off-by: Simon Guinot <simon.guinot@seagate.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.

Re: [PATCH] PCI: fix link retrain status in pcie_wait_for_link_delay()

[simon.guinot]

[-- Attachment #1: Type: text/plain, Size: 1523 bytes --]

On Wed, Mar 13, 2024 at 02:00:21PM +0200, Ilpo Järvinen wrote:
> 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@vger.kernel.org
> > Fixes: 1abb47390350 ("Merge branch 'pci/enumeration'")
> > Signed-off-by: Simon Guinot <simon.guinot@seagate.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.)

Hi Ilpo,

Thanks for pointing this patch series. This indeed fixes the timeout delay
issue I observed.

Simon

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]