Hi,
On Sat, Apr 06, 2024 at 03:52:02PM +0200, Lukas Wunner wrote:
> 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.
>
Not really; see below.
> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
> Acked-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> (powerpc)
> ---
...
> index da79760..5193fae 100644
> --- a/init/initramfs.c
> +++ b/init/initramfs.c
> @@ -575,15 +575,7 @@ static int __init initramfs_async_setup(char *str)
> #include <linux/initrd.h>
> #include <linux/kexec.h>
>
> -static ssize_t raw_read(struct file *file, struct kobject *kobj,
> - struct bin_attribute *attr, char *buf,
> - loff_t pos, size_t count)
> -{
> - memcpy(buf, attr->private + pos, count);
> - return count;
> -}
> -
> -static BIN_ATTR(initrd, 0440, raw_read, NULL, 0);
> +static BIN_ATTR(initrd, 0440, sysfs_bin_attr_simple_read, NULL, 0);
>
sysfs_bin_attr_simple_read is only declared and available if CONFIG_SYSFS=y.
With m68k:m5208evb_defconfig + CONFIG_BLK_DEV_INITRD=y, this results in
/opt/buildbot/slave/qemu-m68k/build/init/initramfs.c:578:31:
error: 'sysfs_bin_attr_simple_read' undeclared here (not in a function)
This happens because CONFIG_SYSFS=n and there is no dummy function for
sysfs_bin_attr_simple_read(). Presumably the problem will be seen for all
configurations with CONFIG_BLK_DEV_INITRD=y and CONFIG_SYSFS=n.
On a side note, init/initramfs.c does not directly include linux/sysfs.h.
I don't know if that might cause problems with other builds.
Guenter
