linux-kernel - Re: [PATCH] mmc-core: One check less in mmc_select

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Date:	Tue, 12 Jan 2016 16:07:12 +0100
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	SF Markus Elfring <elfring@...rs.sourceforge.net>
Cc:	linux-mmc <linux-mmc@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org,
	Julia Lawall <julia.lawall@...6.fr>
Subject: Re: [PATCH] mmc-core: One check less in mmc_select_hs200() after
 error detection

On 29 December 2015 at 20:50, SF Markus Elfring
<elfring@...rs.sourceforge.net> wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Tue, 29 Dec 2015 20:28:46 +0100
>
> This issue was detected by using the Coccinelle software.
>
> Move the jump label directly before the desired log statement
> so that the variable "err" will not be checked once more
> after it was determined that a call of the function
> "__mmc_set_signal_voltage" or "__mmc_switch" failed.
> Use the identifier "report_failure" instead of the label "err".

I understand the report, but this unfortunate not the proper solution.

Instead, the "if (err)" check should be entirely removed from the err label.

To do that, mmc_select_hs200() should pre validate whether 4 or 8 -bit
bus is supported which then prevents starting to switch to hs200
unless really supported. Moreover it means mmc_select_bus_width()
shall return 0 to indicate success instead of as now, returning a
positive value or 0.

Kind regards
Uffe

>
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>  drivers/mmc/core/mmc.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 549c56e..866f72b 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1256,7 +1256,7 @@ static int mmc_select_hs200(struct mmc_card *card)
>
>         /* If fails try again during next card power cycle */
>         if (err)
> -               goto err;
> +               goto report_failure;
>
>         mmc_select_driver_type(card);
>
> @@ -1276,7 +1276,7 @@ static int mmc_select_hs200(struct mmc_card *card)
>                                    card->ext_csd.generic_cmd6_time,
>                                    true, send_status, true);
>                 if (err)
> -                       goto err;
> +                       goto report_failure;
>                 old_timing = host->ios.timing;
>                 mmc_set_timing(host, MMC_TIMING_MMC_HS200);
>                 if (!send_status) {
> @@ -1289,10 +1289,11 @@ static int mmc_select_hs200(struct mmc_card *card)
>                                 mmc_set_timing(host, old_timing);
>                 }
>         }
> -err:
> -       if (err)
> +       if (err) {
> +report_failure:
>                 pr_err("%s: %s failed, error %d\n", mmc_hostname(card->host),
>                        __func__, err);
> +       }
>         return err;
>  }
>
> --
> 2.6.3
>