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

[Neil Armstrong]

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@xxxxxxxxxxxx>
>> ---
>>  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 */