linux-kernel - Re: [PATCH v7 09/13] PCI: Give pcim_set

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Message-ID: <17445053-18a1-a56d-79d0-3b3d3ecab033@linux.intel.com>
Date: Thu, 13 Jun 2024 20:19:47 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Philipp Stanner <pstanner@...hat.com>
cc: Hans de Goede <hdegoede@...hat.com>, 
    Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
    Maxime Ripard <mripard@...nel.org>, 
    Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
    Daniel Vetter <daniel@...ll.ch>, Bjorn Helgaas <bhelgaas@...gle.com>, 
    Sam Ravnborg <sam@...nborg.org>, dakr@...hat.com, 
    dri-devel@...ts.freedesktop.org, LKML <linux-kernel@...r.kernel.org>, 
    linux-pci@...r.kernel.org
Subject: Re: [PATCH v7 09/13] PCI: Give pcim_set_mwi() its own devres
 callback

On Wed, 5 Jun 2024, Philipp Stanner wrote:

> Managing pci_set_mwi() with devres can easily be done with its own
> callback, without the necessity to store any state about it in a
> device-related struct.
> 
> Remove the MWI state from struct pci_devres.
> Give pcim_set_mwi() a separate devres-callback.
> 
> Signed-off-by: Philipp Stanner <pstanner@...hat.com>
> ---
>  drivers/pci/devres.c | 29 ++++++++++++++++++-----------
>  drivers/pci/pci.h    |  1 -
>  2 files changed, 18 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
> index 936369face4b..0bafb67e1886 100644
> --- a/drivers/pci/devres.c
> +++ b/drivers/pci/devres.c
> @@ -361,24 +361,34 @@ void __iomem *devm_pci_remap_cfg_resource(struct device *dev,
>  }
>  EXPORT_SYMBOL(devm_pci_remap_cfg_resource);
>  
> +static void __pcim_clear_mwi(void *pdev_raw)
> +{
> +	struct pci_dev *pdev = pdev_raw;
> +
> +	pci_clear_mwi(pdev);
> +}
> +
>  /**
>   * pcim_set_mwi - a device-managed pci_set_mwi()
> - * @dev: the PCI device for which MWI is enabled
> + * @pdev: the PCI device for which MWI is enabled
>   *
>   * Managed pci_set_mwi().
>   *
>   * RETURNS: An appropriate -ERRNO error value on error, or zero for success.
>   */
> -int pcim_set_mwi(struct pci_dev *dev)
> +int pcim_set_mwi(struct pci_dev *pdev)
>  {
> -	struct pci_devres *dr;
> +	int ret;
>  
> -	dr = find_pci_dr(dev);
> -	if (!dr)
> -		return -ENOMEM;
> +	ret = devm_add_action(&pdev->dev, __pcim_clear_mwi, pdev);
> +	if (ret != 0)
> +		return ret;
> +
> +	ret = pci_set_mwi(pdev);
> +	if (ret != 0)
> +		devm_remove_action(&pdev->dev, __pcim_clear_mwi, pdev);

I'm sorry if this is a stupid question but why this cannot use 
devm_add_action_or_reset()?

> -	dr->mwi = 1;
> -	return pci_set_mwi(dev);
> +	return ret;
>  }
>  EXPORT_SYMBOL(pcim_set_mwi);

-- 
 i.