Re: [ndctl PATCH v11 4/7] cxl/event_trace: add helpers to retrieve tep fields by type

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

On 3/13/24 9:05 PM, alison.schofield@intel.com wrote:
> From: Alison Schofield <alison.schofield@intel.com>
> 
> Add helpers to extract the value of an event record field given the
> field name. This is useful when the user knows the name and format
> of the field and simply needs to get it. The helpers also return
> the 'type'_MAX of the type when the field is
> 
> Since this is in preparation for adding a cxl_poison private parser
> for 'cxl list --media-errors' support those specific required
> types: u8, u32, u64.
> 
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  cxl/event_trace.c | 37 +++++++++++++++++++++++++++++++++++++
>  cxl/event_trace.h |  8 +++++++-
>  2 files changed, 44 insertions(+), 1 deletion(-)
> 
> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
> index 640abdab67bf..324edb982888 100644
> --- a/cxl/event_trace.c
> +++ b/cxl/event_trace.c
> @@ -15,6 +15,43 @@
>  #define _GNU_SOURCE
>  #include <string.h>
>  
> +u64 cxl_get_field_u64(struct tep_event *event, struct tep_record *record,
> +		      const char *name)
> +{
> +	unsigned long long val;
> +
> +	if (tep_get_field_val(NULL, event, name, record, &val, 0))
> +		return ULLONG_MAX;
> +
> +	return val;
> +}
> +
> +u32 cxl_get_field_u32(struct tep_event *event, struct tep_record *record,
> +		      const char *name)
> +{
> +	char *val;
> +	int len;
> +
> +	val = tep_get_field_raw(NULL, event, name, record, &len, 0);
> +	if (!val)
> +		return UINT_MAX;
> +
> +	return *(u32 *)val;
> +}
> +
> +u8 cxl_get_field_u8(struct tep_event *event, struct tep_record *record,
> +		    const char *name)
> +{
> +	char *val;
> +	int len;
> +
> +	val = tep_get_field_raw(NULL, event, name, record, &len, 0);
> +	if (!val)
> +		return UCHAR_MAX;
> +
> +	return *(u8 *)val;
> +}
> +
>  static struct json_object *num_to_json(void *num, int elem_size, unsigned long flags)
>  {
>  	bool sign = flags & TEP_FIELD_IS_SIGNED;
> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
> index b77cafb410c4..7b30c3922aef 100644
> --- a/cxl/event_trace.h
> +++ b/cxl/event_trace.h
> @@ -5,6 +5,7 @@
>  
>  #include <json-c/json.h>
>  #include <ccan/list/list.h>
> +#include <ccan/short_types/short_types.h>
>  
>  struct jlist_node {
>  	struct json_object *jobj;
> @@ -32,5 +33,10 @@ int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx);
>  int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system,
>  		const char *event);
>  int cxl_event_tracing_disable(struct tracefs_instance *inst);
> -
> +u8 cxl_get_field_u8(struct tep_event *event, struct tep_record *record,
> +		    const char *name);
> +u32 cxl_get_field_u32(struct tep_event *event, struct tep_record *record,
> +		      const char *name);
> +u64 cxl_get_field_u64(struct tep_event *event, struct tep_record *record,
> +		      const char *name);
>  #endif