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    Subject[PATCH AUTOSEL 5.3 043/203] soc: amlogic: meson-clk-measure: protect measure with a mutex
    Date
    From: Neil Armstrong <narmstrong@baylibre.com>

    [ Upstream commit 3a760d986568b67d1f8411dab64608075817b90d ]

    In order to protect clock measuring when multiple process asks for
    a measure, protect the main measure function with mutexes.

    Reviewed-by: Kevin Hilman <khilman@baylibre.com>
    Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
    Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
    Signed-off-by: Kevin Hilman <khilman@baylibre.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 19d4cbc93a17a..c470e24f1dfa6 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);
    + if (ret)
    + return ret;
    +
    regmap_write(priv->regmap, MSR_CLK_REG0, 0);

    /* Set measurement duration */
    @@ -377,8 +383,10 @@ static int meson_measure_id(struct meson_msr_id *clk_msr_id,

    ret = regmap_read_poll_timeout(priv->regmap, MSR_CLK_REG0,
    val, !(val & MSR_BUSY), 10, 10000);
    - if (ret)
    + if (ret) {
    + mutex_unlock(&measure_lock);
    return ret;
    + }

    /* Disable */
    regmap_update_bits(priv->regmap, MSR_CLK_REG0, MSR_ENABLE, 0);
    @@ -386,6 +394,8 @@ static int meson_measure_id(struct meson_msr_id *clk_msr_id,
    /* Get the value in multiple of gate time counts */
    regmap_read(priv->regmap, MSR_CLK_REG2, &val);

    + mutex_unlock(&measure_lock);
    +
    if (val >= MSR_VAL_MASK)
    return -EINVAL;

    --
    2.20.1
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