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SubjectRe: [RFC/RFT 05/14] soc: amlogic: meson-clk-measure: protect measure with a mutex
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On 25/06/2019 22:27, Stephen Boyd wrote:
> 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@baylibre.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?


I supposed _interruptible was needed since it's called from userspace via
debugfs, locking indefinitely isn't wanted, no ? or maybe I missed something...

Neil

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

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