On Wed, May 22, 2024 at 07:51:35PM -0700, Guenter Roeck wrote:

Hi,

On Sat, Apr 06, 2024 at 03:52:02PM +0200, Lukas Wunner wrote:

quoted

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.

quoted

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
---

...

quoted

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.

Lukas, can you send a patch adding a dummy function?

thanks,

greg k-h