Subject: Re: [PATCH 2/2] treewide: Use sysfs_bin_attr_simple_read() helper

From: Michael Ellerman <[email-masked]>
Date: Mon, 08 Apr 2024 21:11:57 +1000

Lukas Wunner <[email-masked]> writes:
> Deduplicate ->read() callbacks of bin_attributes which are backed by a
> simple buffer in memory:
>
> Use the newly introduced sysfs_bin_attr_simple_read() helper instead,
> either by referencing it directly or by declaring such bin_attributes
> with BIN_ATTR_SIMPLE_RO() or BIN_ATTR_SIMPLE_ADMIN_RO().
>
> Aside from a reduction of LoC, this shaves off a few bytes from vmlinux
> (304 bytes on an x86_64 allyesconfig).
>
> No functional change intended.
>
> Signed-off-by: Lukas Wunner <[email-masked]>
> ---
>  arch/powerpc/platforms/powernv/opal.c              | 10 +--------
>  drivers/acpi/bgrt.c                                |  9 +-------
>  drivers/firmware/dmi_scan.c                        | 12 ++--------
>  drivers/firmware/efi/rci2-table.c                  | 10 +--------
>  drivers/gpu/drm/i915/gvt/firmware.c                | 26 +++++-----------------
>  .../intel/int340x_thermal/int3400_thermal.c        |  9 +-------
>  init/initramfs.c                                   | 10 +--------
>  kernel/module/sysfs.c                              | 13 +----------
>  8 files changed, 14 insertions(+), 85 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
> index 45dd77e..5d0f35b 100644
> --- a/arch/powerpc/platforms/powernv/opal.c
> +++ b/arch/powerpc/platforms/powernv/opal.c
> @@ -792,14 +792,6 @@ static int __init opal_sysfs_init(void)
>  	return 0;
>  }
>  
> -static ssize_t export_attr_read(struct file *fp, struct kobject *kobj,
> -				struct bin_attribute *bin_attr, char *buf,
> -				loff_t off, size_t count)
> -{
> -	return memory_read_from_buffer(buf, count, &off, bin_attr->private,
> -				       bin_attr->size);
> -}
> -
>  static int opal_add_one_export(struct kobject *parent, const char *export_name,
>  			       struct device_node *np, const char *prop_name)
>  {
> @@ -826,7 +818,7 @@ static int opal_add_one_export(struct kobject *parent, const char *export_name,
>  	sysfs_bin_attr_init(attr);
>  	attr->attr.name = name;
>  	attr->attr.mode = 0400;
> -	attr->read = export_attr_read;
> +	attr->read = sysfs_bin_attr_simple_read;
>  	attr->private = __va(vals[0]);
>  	attr->size = vals[1];

I gave it a quick boot and checked I could still read the attributes,
everything seems fine.

Acked-by: Michael Ellerman <[email-masked]> (powerpc)

cheers