The utility macro from the sysfs core is sufficient to implement this
attribute. Make use of it.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
Changes in v2:
- Use __BIN_ATTR_SIMPLE_RO() (Thanks Masahiro)
- Link to v1: https://lore.kernel.org/r/20241215-sysfs-const-bin_attr-kheaders-v1-1-319bbd50e224@weissschuh.net
---
__BIN_ATTR() is used over the normal struct initializer because it is
shorter and can also handle the transition to const struct bin_attr
callbacks.
If you prefer, I can switch that back, but it will introduce a trivial
conflict with [0].

Note: There is no formal maintainer for that source file.

[0] https://lore.kernel.org/lkml/20241205-sysfs-const-bin_attr-simple-v1-0-4a4e4ced71e3@weissschuh.net/
---
 kernel/kheaders.c | 19 +++----------------
 1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/kernel/kheaders.c b/kernel/kheaders.c
index 42163c9e94e557c5043e2ac7987b567f23087ee2..378088b07f46d643736c04b9075f631e0dc2a53d 100644
--- a/kernel/kheaders.c
+++ b/kernel/kheaders.c
@@ -29,25 +29,12 @@ asm (
 extern char kernel_headers_data[];
 extern char kernel_headers_data_end[];
 
-static ssize_t
-ikheaders_read(struct file *file,  struct kobject *kobj,
-	       struct bin_attribute *bin_attr,
-	       char *buf, loff_t off, size_t len)
-{
-	memcpy(buf, &kernel_headers_data[off], len);
-	return len;
-}
-
-static struct bin_attribute kheaders_attr __ro_after_init = {
-	.attr = {
-		.name = "kheaders.tar.xz",
-		.mode = 0444,
-	},
-	.read = &ikheaders_read,
-};
+static struct bin_attribute kheaders_attr __ro_after_init =
+	__BIN_ATTR_SIMPLE_RO(kheaders.tar.xz, 0444);
 
 static int __init ikheaders_init(void)
 {
+	kheaders_attr.private = kernel_headers_data;
 	kheaders_attr.size = (kernel_headers_data_end -
 			      kernel_headers_data);
 	return sysfs_create_bin_file(kernel_kobj, &kheaders_attr);

---
base-commit: 499551201b5f4fd3c0618a3e95e3d0d15ea18f31
change-id: 20241215-sysfs-const-bin_attr-kheaders-440887f23892

Best regards,
-- 
Thomas Weißschuh <linux@weissschuh.net>

On Sat, Dec 21, 2024 at 11:09 PM Thomas Weißschuh <linux@weissschuh.net> wrote:
>
> The utility macro from the sysfs core is sufficient to implement this
> attribute. Make use of it.
>
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>


Applied to linux-kbuild. Thanks.

> ---
> Changes in v2:
> - Use __BIN_ATTR_SIMPLE_RO() (Thanks Masahiro)
> - Link to v1: https://lore.kernel.org/r/20241215-sysfs-const-bin_attr-kheaders-v1-1-319bbd50e224@weissschuh.net
> ---
> __BIN_ATTR() is used over the normal struct initializer because it is
> shorter and can also handle the transition to const struct bin_attr
> callbacks.
> If you prefer, I can switch that back, but it will introduce a trivial
> conflict with [0].
>
> Note: There is no formal maintainer for that source file.
>
> [0] https://lore.kernel.org/lkml/20241205-sysfs-const-bin_attr-simple-v1-0-4a4e4ced71e3@weissschuh.net/
> ---
>  kernel/kheaders.c | 19 +++----------------
>  1 file changed, 3 insertions(+), 16 deletions(-)
>
> diff --git a/kernel/kheaders.c b/kernel/kheaders.c
> index 42163c9e94e557c5043e2ac7987b567f23087ee2..378088b07f46d643736c04b9075f631e0dc2a53d 100644
> --- a/kernel/kheaders.c
> +++ b/kernel/kheaders.c
> @@ -29,25 +29,12 @@ asm (
>  extern char kernel_headers_data[];
>  extern char kernel_headers_data_end[];
>
> -static ssize_t
> -ikheaders_read(struct file *file,  struct kobject *kobj,
> -              struct bin_attribute *bin_attr,
> -              char *buf, loff_t off, size_t len)
> -{
> -       memcpy(buf, &kernel_headers_data[off], len);
> -       return len;
> -}
> -
> -static struct bin_attribute kheaders_attr __ro_after_init = {
> -       .attr = {
> -               .name = "kheaders.tar.xz",
> -               .mode = 0444,
> -       },
> -       .read = &ikheaders_read,
> -};
> +static struct bin_attribute kheaders_attr __ro_after_init =
> +       __BIN_ATTR_SIMPLE_RO(kheaders.tar.xz, 0444);
>
>  static int __init ikheaders_init(void)
>  {
> +       kheaders_attr.private = kernel_headers_data;
>         kheaders_attr.size = (kernel_headers_data_end -
>                               kernel_headers_data);
>         return sysfs_create_bin_file(kernel_kobj, &kheaders_attr);
>
> ---
> base-commit: 499551201b5f4fd3c0618a3e95e3d0d15ea18f31
> change-id: 20241215-sysfs-const-bin_attr-kheaders-440887f23892
>
> Best regards,
> --
> Thomas Weißschuh <linux@weissschuh.net>
>


-- 
Best Regards
Masahiro Yamada

Hi Masahiro,

On 2024-12-28 23:52:13+0900, Masahiro Yamada wrote:
> On Sat, Dec 21, 2024 at 11:09 PM Thomas Weißschuh <linux@weissschuh.net> wrote:
> >
> > The utility macro from the sysfs core is sufficient to implement this
> > attribute. Make use of it.
> >
> > Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> 
> 
> Applied to linux-kbuild. Thanks.

Thanks, but FYI it is also already applied to the driver-core tree.
Unfortunately Greg's confirmation mails don't go to the list.

IMO having an explicit maintainer for this file could avoid this issue
in the future.

> > ---
> > Changes in v2:
> > - Use __BIN_ATTR_SIMPLE_RO() (Thanks Masahiro)
> > - Link to v1: https://lore.kernel.org/r/20241215-sysfs-const-bin_attr-kheaders-v1-1-319bbd50e224@weissschuh.net
> > ---
> > __BIN_ATTR() is used over the normal struct initializer because it is
> > shorter and can also handle the transition to const struct bin_attr
> > callbacks.
> > If you prefer, I can switch that back, but it will introduce a trivial
> > conflict with [0].
> >
> > Note: There is no formal maintainer for that source file.
> >
> > [0] https://lore.kernel.org/lkml/20241205-sysfs-const-bin_attr-simple-v1-0-4a4e4ced71e3@weissschuh.net/
> > ---
> >  kernel/kheaders.c | 19 +++----------------
> >  1 file changed, 3 insertions(+), 16 deletions(-)
> >
> > diff --git a/kernel/kheaders.c b/kernel/kheaders.c
> > index 42163c9e94e557c5043e2ac7987b567f23087ee2..378088b07f46d643736c04b9075f631e0dc2a53d 100644
> > --- a/kernel/kheaders.c
> > +++ b/kernel/kheaders.c
> > @@ -29,25 +29,12 @@ asm (
> >  extern char kernel_headers_data[];
> >  extern char kernel_headers_data_end[];
> >
> > -static ssize_t
> > -ikheaders_read(struct file *file,  struct kobject *kobj,
> > -              struct bin_attribute *bin_attr,
> > -              char *buf, loff_t off, size_t len)
> > -{
> > -       memcpy(buf, &kernel_headers_data[off], len);
> > -       return len;
> > -}
> > -
> > -static struct bin_attribute kheaders_attr __ro_after_init = {
> > -       .attr = {
> > -               .name = "kheaders.tar.xz",
> > -               .mode = 0444,
> > -       },
> > -       .read = &ikheaders_read,
> > -};
> > +static struct bin_attribute kheaders_attr __ro_after_init =
> > +       __BIN_ATTR_SIMPLE_RO(kheaders.tar.xz, 0444);
> >
> >  static int __init ikheaders_init(void)
> >  {
> > +       kheaders_attr.private = kernel_headers_data;
> >         kheaders_attr.size = (kernel_headers_data_end -
> >                               kernel_headers_data);
> >         return sysfs_create_bin_file(kernel_kobj, &kheaders_attr);
> >
> > ---
> > base-commit: 499551201b5f4fd3c0618a3e95e3d0d15ea18f31
> > change-id: 20241215-sysfs-const-bin_attr-kheaders-440887f23892
> >
> > Best regards,
> > --
> > Thomas Weißschuh <linux@weissschuh.net>
> >
> 
> 
> -- 
> Best Regards
> Masahiro Yamada

On Sat, Dec 28, 2024 at 11:57 PM Thomas Weißschuh <linux@weissschuh.net> wrote:
>
> Hi Masahiro,
>
> On 2024-12-28 23:52:13+0900, Masahiro Yamada wrote:
> > On Sat, Dec 21, 2024 at 11:09 PM Thomas Weißschuh <linux@weissschuh.net> wrote:
> > >
> > > The utility macro from the sysfs core is sufficient to implement this
> > > attribute. Make use of it.
> > >
> > > Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> >
> >
> > Applied to linux-kbuild. Thanks.
>
> Thanks, but FYI it is also already applied to the driver-core tree.
> Unfortunately Greg's confirmation mails don't go to the list.

OK, I will drop it.






-- 
Best Regards
Masahiro Yamada