Re: [PATCH v3 03/10] cxl: add common function to enable event trace

[Dave Jiang <dave.jiang@intel.com>]

On 11/2/2022 11:00 PM, Steven Rostedt wrote:
> On Wed, 02 Nov 2022 14:20:21 -0700
> Dave Jiang <dave.jiang@intel.com> wrote:
> 
>> Add a common function for cxl command to enable event tracing for the
>> instance created. The interested "systems" will be enabled for tracing
>> as well.
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>>   cxl/event_trace.c |   21 +++++++++++++++++++++
>>   cxl/event_trace.h |    1 +
>>   2 files changed, 22 insertions(+)
>>
>> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
>> index cf63d2346f6e..d59e54c33df6 100644
>> --- a/cxl/event_trace.c
>> +++ b/cxl/event_trace.c
>> @@ -200,3 +200,24 @@ int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx)
>>   	tep_free(tep);
>>   	return rc;
>>   }
>> +
>> +int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system)
>> +{
>> +	int rc;
>> +	char *path;
>> +
>> +	rc = asprintf(&path, "events/%s/enable", system);
>> +	if (rc == -1)
>> +		return -errno;
>> +
>> +	rc = tracefs_instance_file_write(inst, path, "1");
>> +	free(path);
>> +	if (rc == -1)
>> +		return -errno;
> 
> Latest libtracefs has:
> 
> 	tracefs_event_enable(inst, system, NULL);
> 
> That enables all events for a system in the instance "inst".

Great. Thanks! I will switch to that.

> 
> -- Steve
> 
> 
>> +
>> +	if (tracefs_trace_is_on(inst))
>> +		return 0;
>> +
>> +	tracefs_trace_on(inst);
>> +	return 0;
>> +}
>> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
>> index 582882c1eb35..0258b8dc65a3 100644
>> --- a/cxl/event_trace.h
>> +++ b/cxl/event_trace.h
>> @@ -20,5 +20,6 @@ struct event_ctx {
>>   };
>>   
>>   int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx);
>> +int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system);
>>   
>>   #endif
>>
>