linux-kernel - Re: [RFC/RFT 05/14] soc: amlogic: meson-clk-measure: protect measure with a mutex

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Message-Id: <20190625202702.B9A9B208CB@mail.kernel.org>
Date:   Tue, 25 Jun 2019 13:27:01 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Neil Armstrong <narmstrong@...libre.com>, jbrunet@...libre.com,
        khilman@...libre.com
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, martin.blumenstingl@...glemail.com,
        Neil Armstrong <narmstrong@...libre.com>
Subject: Re: [RFC/RFT 05/14] soc: amlogic: meson-clk-measure: protect measure with a mutex

Quoting Neil Armstrong (2019-06-20 08:00:04)
> In order to protect clock measuring when multiple process asks for
> a mesure, protect the main measure function with mutexes.
> 
> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
> ---
>  drivers/soc/amlogic/meson-clk-measure.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/amlogic/meson-clk-measure.c b/drivers/soc/amlogic/meson-clk-measure.c
> index 19d4cbc93a17..c470e24f1dfa 100644
> --- a/drivers/soc/amlogic/meson-clk-measure.c
> +++ b/drivers/soc/amlogic/meson-clk-measure.c
> @@ -11,6 +11,8 @@
>  #include <linux/debugfs.h>
>  #include <linux/regmap.h>
>  
> +static DEFINE_MUTEX(measure_lock);
> +
>  #define MSR_CLK_DUTY           0x0
>  #define MSR_CLK_REG0           0x4
>  #define MSR_CLK_REG1           0x8
> @@ -360,6 +362,10 @@ static int meson_measure_id(struct meson_msr_id *clk_msr_id,
>         unsigned int val;
>         int ret;
>  
> +       ret = mutex_lock_interruptible(&measure_lock);

Why interruptible?

> +       if (ret)
> +               return ret;
> +
>         regmap_write(priv->regmap, MSR_CLK_REG0, 0);
>  
>         /* Set measurement duration */