linux-kernel - Re: [PATCH] kheaders: Move from proc to sysfs

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Date:   Sat, 4 May 2019 09:18:06 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Adrian Ratiu <adrian.ratiu@...labora.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        atish patra <atishp04@...il.com>, bpf@...r.kernel.org,
        Brendan Gregg <bgregg@...flix.com>,
        Brendan Gregg <brendan.d.gregg@...il.com>,
        Daniel Colascione <dancol@...gle.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Dan Williams <dan.j.williams@...el.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        duyuchao <yuchao.du@...soc.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <groeck@...omium.org>,
        Jonathan Corbet <corbet@....net>,
        Karim Yaghmour <karim.yaghmour@...rsys.com>,
        Kees Cook <keescook@...omium.org>,
        "Cc: Android Kernel" <kernel-team@...roid.com>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        linux-trace-devel@...r.kernel.org,
        Manjo Raja Rao <linux@...ojrajarao.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Michał Gregorczyk <michalgr@...com>,
        Michal Gregorczyk <michalgr@...e.com>,
        Mohammad Husain <russoue@...il.com>,
        Olof Johansson <olof@...om.net>,
        Qais Yousef <qais.yousef@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Shuah Khan <shuah@...nel.org>,
        Srinivas Ramana <sramana@...eaurora.org>,
        Tamir Carmeli <carmeli.tamir@...il.com>,
        Yonghong Song <yhs@...com>
Subject: Re: [PATCH] kheaders: Move from proc to sysfs

On Sat, May 4, 2019 at 3:27 AM Joel Fernandes (Google)
<joel@...lfernandes.org> wrote:
>
> The kheaders archive consisting of the kernel headers used for compiling
> bpf programs is in /proc. However there is concern that moving it here
> will make it permanent. Let us move it to /sys/kernel as discussed [1].
>
> [1] https://lore.kernel.org/patchwork/patch/1067310/#1265969
>
> Suggested-by: Steven Rostedt <rostedt@...dmis.org>
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> ---
> This patch applies on top of the previous patch that was applied to the
> driver tree:
> https://lore.kernel.org/patchwork/patch/1067310/
>
>  kernel/kheaders.c | 40 ++++++++++++++++------------------------


Please rename CONFIG_IKHEADERS_PROC.

Thanks.




>  1 file changed, 16 insertions(+), 24 deletions(-)
>
> diff --git a/kernel/kheaders.c b/kernel/kheaders.c
> index 70ae6052920d..6a16f8f6898d 100644
> --- a/kernel/kheaders.c
> +++ b/kernel/kheaders.c
> @@ -8,9 +8,8 @@
>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> -#include <linux/proc_fs.h>
> +#include <linux/kobject.h>
>  #include <linux/init.h>
> -#include <linux/uaccess.h>
>
>  /*
>   * Define kernel_headers_data and kernel_headers_data_end, within which the
> @@ -31,39 +30,32 @@ extern char kernel_headers_data;
>  extern char kernel_headers_data_end;
>
>  static ssize_t
> -ikheaders_read_current(struct file *file, char __user *buf,
> -                     size_t len, loff_t *offset)
> +ikheaders_read(struct file *file,  struct kobject *kobj,
> +              struct bin_attribute *bin_attr,
> +              char *buf, loff_t off, size_t len)
>  {
> -       return simple_read_from_buffer(buf, len, offset,
> -                                      &kernel_headers_data,
> -                                      &kernel_headers_data_end -
> -                                      &kernel_headers_data);
> +       memcpy(buf, &kernel_headers_data + off, len);
> +       return len;
>  }
>
> -static const struct file_operations ikheaders_file_ops = {
> -       .read = ikheaders_read_current,
> -       .llseek = default_llseek,
> +static struct bin_attribute kheaders_attr __ro_after_init = {
> +       .attr = {
> +               .name = "kheaders.tar.xz",
> +               .mode = S_IRUGO,
> +       },
> +       .read = &ikheaders_read,
>  };
>
>  static int __init ikheaders_init(void)
>  {
> -       struct proc_dir_entry *entry;
> -
> -       /* create the current headers file */
> -       entry = proc_create("kheaders.tar.xz", S_IRUGO, NULL,
> -                           &ikheaders_file_ops);
> -       if (!entry)
> -               return -ENOMEM;
> -
> -       proc_set_size(entry,
> -                     &kernel_headers_data_end -
> -                     &kernel_headers_data);
> -       return 0;
> +       kheaders_attr.size = (&kernel_headers_data_end -
> +                             &kernel_headers_data);
> +       return sysfs_create_bin_file(kernel_kobj, &kheaders_attr);
>  }
>
>  static void __exit ikheaders_cleanup(void)
>  {
> -       remove_proc_entry("kheaders.tar.xz", NULL);
> +       sysfs_remove_bin_file(kernel_kobj, &kheaders_attr);
>  }
>
>  module_init(ikheaders_init);
> --
> 2.21.0.1020.gf2820cf01a-goog



-- 
Best Regards
Masahiro Yamada