linux-kernel - Re: [PATCH 01/14] lib/vsprintf.c: pull out padding code from dentry

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Message-ID: <CAHp75Ve_L1K5cat7DX8K67ZWqbyigmwHRkyTqXbCanX+3sASVA@mail.gmail.com>
Date:	Tue, 24 Nov 2015 00:56:27 +0200
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Ingo Molnar <mingo@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/14] lib/vsprintf.c: pull out padding code from dentry_name()

On Mon, Nov 23, 2015 at 11:29 PM, Rasmus Villemoes
<linux@...musvillemoes.dk> wrote:
> Pull out the logic in dentry_name() which handles field width space
> padding, in preparation for reusing it from string(). Rename the
> widen() helper to move_right(), since it is used for handling the
> !(flags & LEFT) case.
>
> Cc: Al Viro <viro@...IV.linux.org.uk>
> Cc: Ingo Molnar <mingo@...nel.org>
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
> ---
>  lib/vsprintf.c | 46 +++++++++++++++++++++++++++++++---------------
>  1 file changed, 31 insertions(+), 15 deletions(-)
>
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index f9cee8e1233c..d7452563a6a6 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -538,7 +538,7 @@ char *string(char *buf, char *end, const char *s, struct printf_spec spec)
>         return buf;
>  }
>
> -static void widen(char *buf, char *end, unsigned len, unsigned spaces)
> +static void move_right(char *buf, char *end, unsigned len, unsigned spaces)
>  {
>         size_t size;
>         if (buf >= end) /* nowhere to put anything */
> @@ -556,6 +556,35 @@ static void widen(char *buf, char *end, unsigned len, unsigned spaces)
>         memset(buf, ' ', spaces);
>  }
>
> +/*

Perhaps /**

> + * Handle field width padding for a string.
> + * @buf: current buffer position
> + * @n: length of string
> + * @end: end of output buffer
> + * @spec: for field width and flags
> + * Returns: new buffer position after padding.
> + */
> +static noinline_for_stack
> +char *widen_string(char *buf, int n, char *end, struct printf_spec spec)
> +{
> +       unsigned spaces;
> +
> +       if (likely(n >= spec.field_width))

> +               return buf;
> +       /* we want to pad the sucker */
> +       spaces = spec.field_width - n;
> +       if (!(spec.flags & LEFT)) {
> +               move_right(buf - n, end, n, spaces);
> +               return buf + spaces;
> +       }
> +       while (spaces--) {
> +               if (buf < end)
> +                       *buf = ' ';
> +               ++buf;
> +       }
> +       return buf;
> +}
> +
>  static noinline_for_stack
>  char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_spec spec,
>                   const char *fmt)
> @@ -597,20 +626,7 @@ char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_sp
>                         *buf = c;
>         }
>         rcu_read_unlock();
> -       if (n < spec.field_width) {
> -               /* we want to pad the sucker */
> -               unsigned spaces = spec.field_width - n;
> -               if (!(spec.flags & LEFT)) {
> -                       widen(buf - n, end, n, spaces);
> -                       return buf + spaces;
> -               }
> -               while (spaces--) {
> -                       if (buf < end)
> -                               *buf = ' ';
> -                       ++buf;
> -               }
> -       }
> -       return buf;
> +       return widen_string(buf, n, end, spec);
>  }
>
>  static noinline_for_stack
> --
> 2.6.1
>
> --
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-- 
With Best Regards,
Andy Shevchenko
--
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