linux-kernel - Re: [PATCH] Fix warning and undefined behavior in mmc voltage handling

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Date:   Tue, 16 Apr 2019 09:48:51 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Pavel Machek <pavel@....cz>
Cc:     kernel list <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...l.org>,
        Trivial patch monkey <trivial@...nel.org>
Subject: Re: [PATCH] Fix warning and undefined behavior in mmc voltage handling

On Fri, 12 Apr 2019 at 11:34, Pavel Machek <pavel@....cz> wrote:
>
> !voltage_ranges is tested for too late, allowing warning and undefined
> behavior. Fix that.
>
> Signed-off-by: Pavel Machek <pavel@....cz>

Pavel, thanks for your patch.

Would you mind re-posting to linux-mmc so I can get it into the
patchtracker. Please also change the prefix of the header to "mmc:
core:".

Otherwise this looks good to me.

Kind regards
Uffe

>
> ---
>
> Plus I guess author should add parenthesis in the expression. a / b /
> c is _not_ common idiom.
>
> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> index 3a4402a..b3fa9c9 100644
> --- a/drivers/mmc/core/host.c
> +++ b/drivers/mmc/core/host.c
> @@ -363,11 +363,11 @@ int mmc_of_parse_voltage(struct device_node *np, u32 *mask)
>         int num_ranges, i;
>
>         voltage_ranges = of_get_property(np, "voltage-ranges", &num_ranges);
> -       num_ranges = num_ranges / sizeof(*voltage_ranges) / 2;
>         if (!voltage_ranges) {
>                 pr_debug("%pOF: voltage-ranges unspecified\n", np);
>                 return 0;
>         }
> +       num_ranges = num_ranges / sizeof(*voltage_ranges) / 2;
>         if (!num_ranges) {
>                 pr_err("%pOF: voltage-ranges empty\n", np);
>                 return -EINVAL;
>
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html