Re: [patch 2.6.28-rc4] gpiolib: extend gpio label column width in debugfs file

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 12 Nov 2008 08:56:13 +0200
Jarkko Nikula <jarkko.nikula@nokia.com> wrote:

> There are already various drivers having bigger label than 12 bytes. Most
> of them fit well under 20 bytes but make column width exact so that
> oversized labels don't mess up output alignment.

Please provide before-and-after example output for this sort of change
so that we can better understand its effect.

> Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
> ---
>  drivers/gpio/gpiolib.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index faa1cc6..82020ab 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1134,7 +1134,7 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
>  			continue;
>  
>  		is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
> -		seq_printf(s, " gpio-%-3d (%-12s) %s %s",
> +		seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",
>  			gpio, gdesc->label,
>  			is_out ? "out" : "in ",
>  			chip->get

This is a non-backward-compatible change to a userspace interface.  It
looks like a pretty safe one, but this is always a fairly big deal.

If we're going to make this change then we should backport it to
2.6.27.x, 2.6.26.x and to 2.6.25.x to minimise the chance that someone
will write a parser which works on one kernel version and fails on
another.

David?  Thoughts?