[PATCH] sysfs: Unbreak the build around sysfs_bin_attr_simple_read()

[Rafael J. Wysocki]

On Thu, May 23, 2024 at 1:00 PM Lukas Wunner <lukas at wunner.de> wrote:
>
> Günter reports build breakage for m68k "m5208evb_defconfig" plus
> CONFIG_BLK_DEV_INITRD=y caused by commit 66bc1a173328 ("treewide:
> Use sysfs_bin_attr_simple_read() helper").
>
> The defconfig disables CONFIG_SYSFS, so sysfs_bin_attr_simple_read()
> is not compiled into the kernel.  But init/initramfs.c references
> that function in the initializer of a struct bin_attribute.
>
> Add an empty static inline to avoid the build breakage.
>
> Fixes: 66bc1a173328 ("treewide: Use sysfs_bin_attr_simple_read() helper")
> Reported-by: Guenter Roeck <linux at roeck-us.net>
> Closes: https://lore.kernel.org/r/e12b0027-b199-4de7-b83d-668171447ccc@roeck-us.net
> Signed-off-by: Lukas Wunner <lukas at wunner.de>

Works for me.

Reviewed-by: Rafael J. Wysocki <rafael at kernel.org>

> ---
>  include/linux/sysfs.h | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
> index a7d725fbf739..c4e64dc11206 100644
> --- a/include/linux/sysfs.h
> +++ b/include/linux/sysfs.h
> @@ -750,6 +750,15 @@ static inline int sysfs_emit_at(char *buf, int at, const char *fmt, ...)
>  {
>         return 0;
>  }
> +
> +static inline ssize_t sysfs_bin_attr_simple_read(struct file *file,
> +                                                struct kobject *kobj,
> +                                                struct bin_attribute *attr,
> +                                                char *buf, loff_t off,
> +                                                size_t count)
> +{
> +       return 0;
> +}
>  #endif /* CONFIG_SYSFS */
>
>  static inline int __must_check sysfs_create_file(struct kobject *kobj,
> --
> 2.43.0
>