linux-kernel - Re: [PATCH 1/2] PCI: Use software node API with additional device properties

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Date:   Wed, 29 Sep 2021 12:08:04 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        Zhangfei Gao <zhangfei.gao@...aro.org>
Subject: Re: [PATCH 1/2] PCI: Use software node API with additional device
 properties

[+cc Zhangfei, author of 8304a3a199ee ("PCI: Set dma-can-stall for
HiSilicon chips"), which added this]

On Wed, Sep 29, 2021 at 04:37:28PM +0300, Heikki Krogerus wrote:
> Using device_create_managed_software_node() to inject the
> properties in quirk_huawei_pcie_sva() instead of with the
> old device_add_properties() API.
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

This is fine with me, but please update the subject line and commit
log something like this:

  PCI: Convert to device_create_managed_software_node()

  In quirk_huawei_pcie_sva(), use device_create_managed_software_node()
  instead of device_add_properties() to set the "dma-can-stall"
  property.

  This resolves a software node lifetime issue (see 151f6ff78cdf
  ("software node: Provide replacement for device_add_properties()"))
  and paves the way for removing device_add_properties() completely.

Actually, 8304a3a199ee was merged during the v5.15 merge window, so if
this does in fact fix a lifetime issue, I can merge this before
v5.15-final.

I know *this* quirk applies to AMBA devices, and I assume they cannot
be removed, so there's no actual lifetime problem in this particular
case, but in general it looks like a problem for PCI devices.

> ---
>  drivers/pci/quirks.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index b6b4c803bdc94..fe5eedba47908 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -1850,7 +1850,7 @@ static void quirk_huawei_pcie_sva(struct pci_dev *pdev)
>  	 * can set it directly.
>  	 */
>  	if (!pdev->dev.of_node &&
> -	    device_add_properties(&pdev->dev, properties))
> +	    device_create_managed_software_node(&pdev->dev, properties, NULL))
>  		pci_warn(pdev, "could not add stall property");
>  }
>  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0xa250, quirk_huawei_pcie_sva);
> -- 
> 2.33.0
>