linux-kernel - Re: [PATCH] BUG: pinmux: release only taken pins on error

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Message-ID: <CAFRkauA3_wOMvn05q4nRBA7_S2UnkUs6T1ma8H91o_uFQ-9zxg@mail.gmail.com>
Date:	Wed, 20 Mar 2013 21:21:59 +0800
From:	Axel Lin <axel.lin@...ics.com>
To:	Richard Genoud <richard.genoud@...il.com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Stephen Warren <swarren@...dia.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] BUG: pinmux: release only taken pins on error

2013/3/20 Richard Genoud <richard.genoud@...il.com>:
> commit e38d457de7be63e6ced1ea254aa51466deb1fef0
> pinctrl: pinmux: Release all taken pins in pinmux_enable_setting
>
> Introduced a bug in the release pin mechanism.
> All the pins (taken or not) where released.
> For instance, if a i2c function has already taken pins 5 and 6.
> And the pins of function PHY are requested (pins 3 4 5 6 7).
> The pins 3 and 4 will be taken, pin 5 is already taken, so the function
> fails.
> And we have pins 3 and 4 release, which is ok. But also pins 5 and 6 !.
> And also pin 7 (which will have its mux_usecount to -1...)
>
> This patch reset the original behaviour.
>
> Signed-off-by: Richard Genoud <richard.genoud@...il.com>
> ---
>  drivers/pinctrl/pinmux.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
> index 1a00658..917e830 100644
> --- a/drivers/pinctrl/pinmux.c
> +++ b/drivers/pinctrl/pinmux.c
> @@ -409,6 +409,8 @@ int pinmux_enable_setting(struct pinctrl_setting const *setting)
>                         dev_err(pctldev->dev,
>                                 "could not request pin %d on device %s\n",
>                                 pins[i], pinctrl_dev_get_name(pctldev));
> +                       /* On error release *only* taken pins */
> +                       num_pins = i - 1; /* this pin just failed */
This seems pointless, in the goto err_pin_request path, the code does
not use num_pins variable at all.

>                         goto err_pin_request;

see the code in err_pin_request,
it actually does "while (--i>-0", so it won't call pin_free for the
just failed pin.

err_pin_request:
        /* On error release all taken pins */
        while (--i >= 0)
                pin_free(pctldev, pins[i], NULL);

        return ret;
--
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