Re: [PATCH v3 02/13] coresight: etb10: Fix handling of perf mode

Suzuki K Poulose
2018-07-31T21:32:07Z

On 07/31/2018 06:07 PM, Mathieu Poirier wrote:
> Hello,
>
> On Thu, Jul 26, 2018 at 01:54:40PM +0100, Suzuki K Poulose wrote:
>> If the ETB is already enabled in sysfs mode, the ETB reports
>> success even if a perf mode is requested. Fix this by checking
>> the requested mode.
>>
>> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>> ---
>> drivers/hwtracing/coresight/coresight-etb10.c | 8 ++++++--
>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
>> index 306119e..e5808fd 100644
>> --- a/drivers/hwtracing/coresight/coresight-etb10.c
>> +++ b/drivers/hwtracing/coresight/coresight-etb10.c
>> @@ -148,8 +148,12 @@ static int etb_enable(struct coresight_device *csdev, u32 mode)
>> return -EBUSY;
>>
>> /* Nothing to do, the tracer is already enabled. */
>> - if (val == CS_MODE_SYSFS)
>> - goto out;
>> + if (val == CS_MODE_SYSFS) {
>> + if (mode == CS_MODE_SYSFS)
>> + goto out;
>> + else
>> + return -EBUSY;
>> + }
>
> How about:
>
> if (val == CS_MODE_PERF)
> return -EBUSY;
>
> + /* Don't let perf disturb sysFS sessions */
> + if (val == CS_MODE_SYSFS && mode = CS_MODE_PERF)
> + return -EBUSY;
> +
> /* Nothing to do, the tracer is already enabled. */
> if (val == CS_MODE_SYSFS)
> goto out;
>
>
> I just find it more readable that way.

Sure, thats fine by me.

Cheers
Suzuki