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

From: Andrew Morton
Date: Thu Nov 13 2008 - 20:02:58 EST


On Wed, 12 Nov 2008 08:56:13 +0200
Jarkko Nikula <jarkko.nikula@xxxxxxxxx> 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@xxxxxxxxx>
> ---
> 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?
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