2019-06-20 15:01:06

by Neil Armstrong

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

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 <[email protected]>
---
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);
+ 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;

--
2.21.0

2019-06-25 20:28:46

by Stephen Boyd

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 <[email protected]>
> ---
> 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 */

2019-06-26 08:26:47

by Neil Armstrong

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

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 <[email protected]>
>> ---
>> 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 */

2019-06-26 18:07:33

by Stephen Boyd

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

Quoting Neil Armstrong (2019-06-26 01:24:47)
> 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.

s/mesure/measure/

> >>
> >> Signed-off-by: Neil Armstrong <[email protected]>
> >> ---
> >> 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...
>

Sounds plausible to me.