linux-kernel - Re: [PATCH 32/37] PCI/sysfs: make I/O resource depend on HAS

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Date:   Thu, 5 May 2022 16:41:54 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Niklas Schnelle <schnelle@...ux.ibm.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-pci@...r.kernel.org, Arnd Bergmann <arnd@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH 32/37] PCI/sysfs: make I/O resource depend on HAS_IOPORT

Capitalize "Make" in the subject to match previous drivers/pci
history.

On Fri, Apr 29, 2022 at 03:50:55PM +0200, Niklas Schnelle wrote:
> Exporting I/O resources only makes sense if legacy I/O spaces are
> supported so conditionally add them only if HAS_IOPORT is set.

This doesn't quite match what the patch does.  We still *add* the
sysfs files, it's just that reads/writes return error.

> Co-developed-by: Arnd Bergmann <arnd@...nel.org>
> Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
> ---
>  drivers/pci/pci-sysfs.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index c263ffc5884a..eda258fa4981 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -1091,6 +1091,7 @@ static int pci_mmap_resource_wc(struct file *filp, struct kobject *kobj,
>  	return pci_mmap_resource(kobj, attr, vma, 1);
>  }
>  
> +#ifdef CONFIG_HAS_IOPORT
>  static ssize_t pci_resource_io(struct file *filp, struct kobject *kobj,
>  			       struct bin_attribute *attr, char *buf,
>  			       loff_t off, size_t count, bool write)
> @@ -1149,6 +1150,21 @@ static ssize_t pci_write_resource_io(struct file *filp, struct kobject *kobj,
>  
>  	return pci_resource_io(filp, kobj, attr, buf, off, count, true);
>  }
> +#else
> +static ssize_t pci_read_resource_io(struct file *filp, struct kobject *kobj,
> +				    struct bin_attribute *attr, char *buf,
> +				    loff_t off, size_t count)
> +{
> +	return -ENXIO;
> +}
> +
> +static ssize_t pci_write_resource_io(struct file *filp, struct kobject *kobj,
> +				     struct bin_attribute *attr, char *buf,
> +				     loff_t off, size_t count)
> +{
> +	return -ENXIO;
> +}
> +#endif

I would move the #ifdef inside pci_resource_io().  Only need one
#ifdef and it's closer to the inb/outb.