Re: [PATCH] init/main.c: Remove redundant space from saved_command_line

Re: [PATCH] init/main.c: Remove redundant space from saved_command_line

[Masami Hiramatsu]

On Thu, 11 Apr 2024 09:19:32 +0200
Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> CC Hiramatsu-san (now for real :-)

Thanks!

> 
> On Thu, Apr 11, 2024 at 6:13 AM Yuntao Wang <ytcoode@gmail.com> wrote:
> > extra_init_args ends with a space, so when concatenating extra_init_args
> > to saved_command_line, be sure to remove the extra space.

Hi Yuntao,

Hmm, if you want to trim the end space, you should trim extra_init_args
itself instead of this adjustment. Also, can you share the example?

Thank you,

> >
> > Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> > ---
> >  init/main.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/init/main.c b/init/main.c
> > index 2ca52474d0c3..cf2c22aa0e8c 100644
> > --- a/init/main.c
> > +++ b/init/main.c
> > @@ -660,12 +660,14 @@ static void __init setup_command_line(char *command_line)
> >                         strcpy(saved_command_line + len, extra_init_args);
> >                         len += ilen - 4;        /* strlen(extra_init_args) */
> >                         strcpy(saved_command_line + len,
> > -                               boot_command_line + initargs_offs - 1);
> > +                               boot_command_line + initargs_offs);
> >                 } else {
> >                         len = strlen(saved_command_line);
> >                         strcpy(saved_command_line + len, " -- ");
> >                         len += 4;
> >                         strcpy(saved_command_line + len, extra_init_args);
> > +                       len += ilen - 4; /* strlen(extra_init_args) */
> > +                       saved_command_line[len-1] = '\0'; /* remove trailing space */
> >                 }
> >         }
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> -- 
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68korg
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

Re: [PATCH] init/main.c: Remove redundant space from saved_command_line

[Yuntao Wang]

On Thu, 11 Apr 2024 23:07:45 +0900, Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:

> On Thu, 11 Apr 2024 09:19:32 +0200
> Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> 
> > CC Hiramatsu-san (now for real :-)
> 
> Thanks!
> 
> > 
> > On Thu, Apr 11, 2024 at 6:13 AM Yuntao Wang <ytcoode@gmail.com> wrote:
> > > extra_init_args ends with a space, so when concatenating extra_init_args
> > > to saved_command_line, be sure to remove the extra space.
> 
> Hi Yuntao,
> 
> Hmm, if you want to trim the end space, you should trim extra_init_args
> itself instead of this adjustment. Also, can you share the example?
> 
> Thank you,

At first, I also intended to fix this issue as you suggested. However,
because both extra_command_line and extra_init_args end with a space,
making such a change would require modifications in many places.
That's why I chose this approach instead.

Here are some examples before and after modification:

Before: [    0.829179] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1 '
After:  [    0.032648] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1'

Before: [    0.757217] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1  arg1'
After:  [    0.068184] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1 arg1'

In order to make it easier to observe spaces, I added quotes when outputting saved_command_line.

Note that the first 'before' ends with a space, and there are two spaces between
'bootconfig_arg1' and 'arg1' in the second 'before'.

> > >
> > > Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> > > ---
> > >  init/main.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/init/main.c b/init/main.c
> > > index 2ca52474d0c3..cf2c22aa0e8c 100644
> > > --- a/init/main.c
> > > +++ b/init/main.c
> > > @@ -660,12 +660,14 @@ static void __init setup_command_line(char *command_line)
> > >                         strcpy(saved_command_line + len, extra_init_args);
> > >                         len += ilen - 4;        /* strlen(extra_init_args) */
> > >                         strcpy(saved_command_line + len,
> > > -                               boot_command_line + initargs_offs - 1);
> > > +                               boot_command_line + initargs_offs);
> > >                 } else {
> > >                         len = strlen(saved_command_line);
> > >                         strcpy(saved_command_line + len, " -- ");
> > >                         len += 4;
> > >                         strcpy(saved_command_line + len, extra_init_args);
> > > +                       len += ilen - 4; /* strlen(extra_init_args) */
> > > +                       saved_command_line[len-1] = '\0'; /* remove trailing space */
> > >                 }
> > >         }
> > 
> > Gr{oetje,eeting}s,
> > 
> >                         Geert
> > 
> > -- 
> > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68korg
> > 
> > In personal conversations with technical people, I call myself a hacker. But
> > when I'm talking to journalists I just say "programmer" or something like that.
> >                                 -- Linus Torvalds
> > 
> 
> 
> -- 
> Masami Hiramatsu (Google) <mhiramat@kernel.org>

Re: [PATCH] init/main.c: Remove redundant space from saved_command_line

[Masami Hiramatsu]

On Thu, 11 Apr 2024 23:29:40 +0800
Yuntao Wang <ytcoode@gmail.com> wrote:

> On Thu, 11 Apr 2024 23:07:45 +0900, Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
> 
> > On Thu, 11 Apr 2024 09:19:32 +0200
> > Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > 
> > > CC Hiramatsu-san (now for real :-)
> > 
> > Thanks!
> > 
> > > 
> > > On Thu, Apr 11, 2024 at 6:13 AM Yuntao Wang <ytcoode@gmail.com> wrote:
> > > > extra_init_args ends with a space, so when concatenating extra_init_args
> > > > to saved_command_line, be sure to remove the extra space.
> > 
> > Hi Yuntao,
> > 
> > Hmm, if you want to trim the end space, you should trim extra_init_args
> > itself instead of this adjustment. Also, can you share the example?
> > 
> > Thank you,
> 
> At first, I also intended to fix this issue as you suggested. However,
> because both extra_command_line and extra_init_args end with a space,
> making such a change would require modifications in many places.

You may just need:

if (extra_init_args)
	strim(extra_init_args);

> That's why I chose this approach instead.
> 
> Here are some examples before and after modification:
> 
> Before: [    0.829179] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1 '
> After:  [    0.032648] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1'
> 
> Before: [    0.757217] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1  arg1'
> After:  [    0.068184] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1 arg1'
> 
> In order to make it easier to observe spaces, I added quotes when outputting saved_command_line.

BTW, is this tailing space harm anything? I don't like a cosmetic change.

Thank you,

> 
> Note that the first 'before' ends with a space, and there are two spaces between
> 'bootconfig_arg1' and 'arg1' in the second 'before'.
> 
> > > >
> > > > Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> > > > ---
> > > >  init/main.c | 4 +++-
> > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/init/main.c b/init/main.c
> > > > index 2ca52474d0c3..cf2c22aa0e8c 100644
> > > > --- a/init/main.c
> > > > +++ b/init/main.c
> > > > @@ -660,12 +660,14 @@ static void __init setup_command_line(char *command_line)
> > > >                         strcpy(saved_command_line + len, extra_init_args);
> > > >                         len += ilen - 4;        /* strlen(extra_init_args) */
> > > >                         strcpy(saved_command_line + len,
> > > > -                               boot_command_line + initargs_offs - 1);
> > > > +                               boot_command_line + initargs_offs);
> > > >                 } else {
> > > >                         len = strlen(saved_command_line);
> > > >                         strcpy(saved_command_line + len, " -- ");
> > > >                         len += 4;
> > > >                         strcpy(saved_command_line + len, extra_init_args);
> > > > +                       len += ilen - 4; /* strlen(extra_init_args) */
> > > > +                       saved_command_line[len-1] = '\0'; /* remove trailing space */
> > > >                 }
> > > >         }
> > > 
> > > Gr{oetje,eeting}s,
> > > 
> > >                         Geert
> > > 
> > > -- 
> > > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68korg
> > > 
> > > In personal conversations with technical people, I call myself a hacker. But
> > > when I'm talking to journalists I just say "programmer" or something like that.
> > >                                 -- Linus Torvalds
> > > 
> > 
> > 
> > -- 
> > Masami Hiramatsu (Google) <mhiramat@kernel.org>


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

Re: [PATCH] init/main.c: Remove redundant space from saved_command_line

[Yuntao Wang]

On Fri, 12 Apr 2024 08:08:39 +0900, Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:

> On Thu, 11 Apr 2024 23:29:40 +0800
> Yuntao Wang <ytcoode@gmail.com> wrote:
> 
> > On Thu, 11 Apr 2024 23:07:45 +0900, Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
> > 
> > > On Thu, 11 Apr 2024 09:19:32 +0200
> > > Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > 
> > > > CC Hiramatsu-san (now for real :-)
> > > 
> > > Thanks!
> > > 
> > > > 
> > > > On Thu, Apr 11, 2024 at 6:13 AM Yuntao Wang <ytcoode@gmail.com> wrote:
> > > > > extra_init_args ends with a space, so when concatenating extra_init_args
> > > > > to saved_command_line, be sure to remove the extra space.
> > > 
> > > Hi Yuntao,
> > > 
> > > Hmm, if you want to trim the end space, you should trim extra_init_args
> > > itself instead of this adjustment. Also, can you share the example?
> > > 
> > > Thank you,
> > 
> > At first, I also intended to fix this issue as you suggested. However,
> > because both extra_command_line and extra_init_args end with a space,
> > making such a change would require modifications in many places.
> 
> You may just need:
> 
> if (extra_init_args)
> 	strim(extra_init_args);

Okay, I'll post another patch, making the changes as you suggested.

> > That's why I chose this approach instead.
> > 
> > Here are some examples before and after modification:
> > 
> > Before: [    0.829179] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1 '
> > After:  [    0.032648] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1'
> > 
> > Before: [    0.757217] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1  arg1'
> > After:  [    0.068184] Kernel command line: 'console=ttyS0 debug -- bootconfig_arg1 arg1'
> > 
> > In order to make it easier to observe spaces, I added quotes when outputting saved_command_line.
> 
> BTW, is this tailing space harm anything? I don't like a cosmetic change.
> 
> Thank you,

I think this modification is necessary.

If saved_command_line is only used internally in the kernel, having extra
spaces, while not perfect, is acceptable to me. However, since saved_command_line
can be accessed by users through the /proc/cmdline file, having these extra
spaces here and there makes it look too casual.

> > 
> > Note that the first 'before' ends with a space, and there are two spaces between
> > 'bootconfig_arg1' and 'arg1' in the second 'before'.
> > 
> > > > >
> > > > > Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> > > > > ---
> > > > >  init/main.c | 4 +++-
> > > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/init/main.c b/init/main.c
> > > > > index 2ca52474d0c3..cf2c22aa0e8c 100644
> > > > > --- a/init/main.c
> > > > > +++ b/init/main.c
> > > > > @@ -660,12 +660,14 @@ static void __init setup_command_line(char *command_line)
> > > > >                         strcpy(saved_command_line + len, extra_init_args);
> > > > >                         len += ilen - 4;        /* strlen(extra_init_args) */
> > > > >                         strcpy(saved_command_line + len,
> > > > > -                               boot_command_line + initargs_offs - 1);
> > > > > +                               boot_command_line + initargs_offs);
> > > > >                 } else {
> > > > >                         len = strlen(saved_command_line);
> > > > >                         strcpy(saved_command_line + len, " -- ");
> > > > >                         len += 4;
> > > > >                         strcpy(saved_command_line + len, extra_init_args);
> > > > > +                       len += ilen - 4; /* strlen(extra_init_args) */
> > > > > +                       saved_command_line[len-1] = '\0'; /* remove trailing space */
> > > > >                 }
> > > > >         }
> > > > 
> > > > Gr{oetje,eeting}s,
> > > > 
> > > >                         Geert
> > > > 
> > > > -- 
> > > > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68korg
> > > > 
> > > > In personal conversations with technical people, I call myself a hacker. But
> > > > when I'm talking to journalists I just say "programmer" or something like that.
> > > >                                 -- Linus Torvalds
> > > > 
> > > 
> > > 
> > > -- 
> > > Masami Hiramatsu (Google) <mhiramat@kernel.org>
> 
> 
> -- 
> Masami Hiramatsu (Google) <mhiramat@kernel.org>

[PATCH v2] init/main.c: Remove redundant space from saved_command_line

[Yuntao Wang]

There is a space at the end of extra_init_args. In the current logic,
copying extra_init_args to saved_command_line will cause extra spaces
in saved_command_line here or there. Remove the trailing space from
extra_init_args to make the string in saved_command_line look more perfect.

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
---
v1 -> v2: Fix the issue using the method suggested by Masami

 init/main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/init/main.c b/init/main.c
index 881f6230ee59..0f03dd15e0e2 100644
--- a/init/main.c
+++ b/init/main.c
@@ -627,8 +627,10 @@ static void __init setup_command_line(char *command_line)
 
 	if (extra_command_line)
 		xlen = strlen(extra_command_line);
-	if (extra_init_args)
+	if (extra_init_args) {
+		extra_init_args = strim(extra_init_args); /* remove trailing space */
 		ilen = strlen(extra_init_args) + 4; /* for " -- " */
+	}
 
 	len = xlen + strlen(boot_command_line) + 1;
 
-- 
2.44.0

Re: [PATCH v2] init/main.c: Remove redundant space from saved_command_line

[Masami Hiramatsu]

On Fri, 12 Apr 2024 11:29:50 +0800
Yuntao Wang <ytcoode@gmail.com> wrote:

> There is a space at the end of extra_init_args. In the current logic,
> copying extra_init_args to saved_command_line will cause extra spaces
> in saved_command_line here or there. Remove the trailing space from
> extra_init_args to make the string in saved_command_line look more perfect.
> 
> Signed-off-by: Yuntao Wang <ytcoode@gmail.com>

OK, this looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Let me pick this to bootconfig/for-next.

Thank you,

> ---
> v1 -> v2: Fix the issue using the method suggested by Masami
> 
>  init/main.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/init/main.c b/init/main.c
> index 881f6230ee59..0f03dd15e0e2 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -627,8 +627,10 @@ static void __init setup_command_line(char *command_line)
>  
>  	if (extra_command_line)
>  		xlen = strlen(extra_command_line);
> -	if (extra_init_args)
> +	if (extra_init_args) {
> +		extra_init_args = strim(extra_init_args); /* remove trailing space */
>  		ilen = strlen(extra_init_args) + 4; /* for " -- " */
> +	}
>  
>  	len = xlen + strlen(boot_command_line) + 1;
>  
> -- 
> 2.44.0
> 

-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>