ACK: [PATCH][focal/linux-azure] PCI/sysfs: Convert "config" to static attribute

[Thadeu Lima de Souza Cascardo]

On Mon, Nov 29, 2021 at 07:31:38AM -0700, Tim Gardner wrote:
> From: Krzysztof Wilczyński <kw at linux.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1952621
> 
> The "config" sysfs attribute allows access to either the legacy (PCI and
> PCI-X Mode 1) or the extended (PCI-X Mode 2 and PCIe) device configuration
> space.  Previously it was dynamically created either when a device was
> added (for hot-added devices) or via a late_initcall (for devices present
> at boot):
> 
>   pci_bus_add_devices
>     pci_bus_add_device
>       pci_create_sysfs_dev_files
>         if (!sysfs_initialized)
> 	  return
> 	sysfs_create_bin_file           # for hot-added devices
> 
>   pci_sysfs_init                        # late_initcall
>     sysfs_initialized = 1
>     for_each_pci_dev(pdev)
>       pci_create_sysfs_dev_files(pdev)  # for devices present at boot
> 
> And dynamically removed when the PCI device is stopped and removed:
> 
>   pci_stop_bus_device
>     pci_stop_dev
>       pci_remove_sysfs_dev_files
>         sysfs_remove_bin_file
> 
> This attribute does not need to be created or removed dynamically, so we
> can use a static attribute so the device model takes care of addition and
> removal automatically.
> 
> Convert "config" to a static attribute and use the .is_bin_visible()
> callback to set the correct object size (either 256 bytes or 4 KiB) at
> runtime.
> 
> The pci_sysfs_init() scheme was added in the pre-git era by
> https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/drivers/pci/pci-sysfs.c?id=f6d553444da2
> 
> [bhelgaas: commit log]
> Suggested-by: Oliver O'Halloran <oohall at gmail.com>
> Link: https://lore.kernel.org/r/CAOSf1CHss03DBSDO4PmTtMp0tCEu5kScn704ZEwLKGXQzBfqaA@mail.gmail.com
> Link: https://lore.kernel.org/r/20210416205856.3234481-2-kw@linux.com
> Signed-off-by: Krzysztof Wilczyński <kw at linux.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
> (cherry picked from commit e1d3f3268b0e512ceb811dd4765e476626bde71c)
> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
> ---
>  drivers/pci/pci-sysfs.c | 64 ++++++++++++++++-------------------------
>  1 file changed, 25 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index b78835742526b..399f441e81a4c 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -814,6 +814,29 @@ static ssize_t pci_write_config(struct file *filp, struct kobject *kobj,
>  
>  	return count;
>  }
> +static BIN_ATTR(config, 0644, pci_read_config, pci_write_config, 0);
> +
> +static struct bin_attribute *pci_dev_config_attrs[] = {
> +	&bin_attr_config,
> +	NULL,
> +};
> +
> +static umode_t pci_dev_config_attr_is_visible(struct kobject *kobj,
> +					      struct bin_attribute *a, int n)
> +{
> +	struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
> +
> +	a->size = PCI_CFG_SPACE_SIZE;
> +	if (pdev->cfg_size > PCI_CFG_SPACE_SIZE)
> +		a->size = PCI_CFG_SPACE_EXP_SIZE;
> +
> +	return a->attr.mode;
> +}
> +
> +static const struct attribute_group pci_dev_config_attr_group = {
> +	.bin_attrs = pci_dev_config_attrs,
> +	.is_bin_visible = pci_dev_config_attr_is_visible,
> +};
>  
>  #ifdef HAVE_PCI_LEGACY
>  /**
> @@ -1283,26 +1306,6 @@ static ssize_t pci_read_rom(struct file *filp, struct kobject *kobj,
>  	return count;
>  }
>  
> -static const struct bin_attribute pci_config_attr = {
> -	.attr =	{
> -		.name = "config",
> -		.mode = 0644,
> -	},
> -	.size = PCI_CFG_SPACE_SIZE,
> -	.read = pci_read_config,
> -	.write = pci_write_config,
> -};
> -
> -static const struct bin_attribute pcie_config_attr = {
> -	.attr =	{
> -		.name = "config",
> -		.mode = 0644,
> -	},
> -	.size = PCI_CFG_SPACE_EXP_SIZE,
> -	.read = pci_read_config,
> -	.write = pci_write_config,
> -};
> -
>  static ssize_t reset_store(struct device *dev, struct device_attribute *attr,
>  			   const char *buf, size_t count)
>  {
> @@ -1354,16 +1357,9 @@ int __must_check pci_create_sysfs_dev_files(struct pci_dev *pdev)
>  	if (!sysfs_initialized)
>  		return -EACCES;
>  
> -	if (pdev->cfg_size > PCI_CFG_SPACE_SIZE)
> -		retval = sysfs_create_bin_file(&pdev->dev.kobj, &pcie_config_attr);
> -	else
> -		retval = sysfs_create_bin_file(&pdev->dev.kobj, &pci_config_attr);
> -	if (retval)
> -		goto err;
> -
>  	retval = pci_create_resource_files(pdev);
>  	if (retval)
> -		goto err_config_file;
> +		goto err;
>  
>  	/* If the device has a ROM, try to expose it in sysfs. */
>  	rom_size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
> @@ -1404,11 +1400,6 @@ int __must_check pci_create_sysfs_dev_files(struct pci_dev *pdev)
>  	}
>  err_resource_files:
>  	pci_remove_resource_files(pdev);
> -err_config_file:
> -	if (pdev->cfg_size > PCI_CFG_SPACE_SIZE)
> -		sysfs_remove_bin_file(&pdev->dev.kobj, &pcie_config_attr);
> -	else
> -		sysfs_remove_bin_file(&pdev->dev.kobj, &pci_config_attr);
>  err:
>  	return retval;
>  }
> @@ -1434,12 +1425,6 @@ void pci_remove_sysfs_dev_files(struct pci_dev *pdev)
>  		return;
>  
>  	pci_remove_capabilities_sysfs(pdev);
> -
> -	if (pdev->cfg_size > PCI_CFG_SPACE_SIZE)
> -		sysfs_remove_bin_file(&pdev->dev.kobj, &pcie_config_attr);
> -	else
> -		sysfs_remove_bin_file(&pdev->dev.kobj, &pci_config_attr);
> -
>  	pci_remove_resource_files(pdev);
>  
>  	if (pdev->rom_attr) {
> @@ -1535,6 +1520,7 @@ static const struct attribute_group pci_dev_group = {
>  
>  const struct attribute_group *pci_dev_groups[] = {
>  	&pci_dev_group,
> +	&pci_dev_config_attr_group,
>  	NULL,
>  };
>  
> -- 
> 2.34.1

Upstream, clean cherry-pick. Restricted to linux-azure and tested.

Cascardo.