Re: [PATCH v2] tracing: fix "gfp_t" format for synthetic events

[Steven Rostedt]

On Fri, 18 Oct 2019 09:20:34 +0800
Zhengjun Xing <zhengjun.xing@xxxxxxxxxxxxxxx> wrote:

> In the format of synthetic events, the "gfp_t" is shown as "signed:1",
> but in fact the "gfp_t" is "unsigned", should be shown as "signed:0".
> 
> The issue can be reproduced by the following commands:
> 
> echo 'memlatency u64 lat; unsigned int order; gfp_t gfp_flags; int migratetype' > /sys/kernel/debug/tracing/synthetic_events
> cat  /sys/kernel/debug/tracing/events/synthetic/memlatency/format
> 
> name: memlatency
> ID: 2233
> format:
>         field:unsigned short common_type;       offset:0;       size:2; signed:0;
>         field:unsigned char common_flags;       offset:2;       size:1; signed:0;
>         field:unsigned char common_preempt_count;       offset:3;       size:1; signed:0;
>         field:int common_pid;   offset:4;       size:4; signed:1;
> 
>         field:u64 lat;  offset:8;       size:8; signed:0;
>         field:unsigned int order;       offset:16;      size:4; signed:0;
>         field:gfp_t gfp_flags;  offset:24;      size:4; signed:1;
>         field:int migratetype;  offset:32;      size:4; signed:1;
> 
> print fmt: "lat=%llu, order=%u, gfp_flags=%x, migratetype=%d", REC->lat, REC->order, REC->gfp_flags, REC->migratetype
> 

Tom,

Can you give a Reviewed-by for this?

-- Steve

> Signed-off-by: Zhengjun Xing <zhengjun.xing@xxxxxxxxxxxxxxx>
> ---
>  kernel/trace/trace_events_hist.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 57648c5aa679..7482a1466ebf 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -679,6 +679,8 @@ static bool synth_field_signed(char *type)
>  {
>  	if (str_has_prefix(type, "u"))
>  		return false;
> +	if (strcmp(type, "gfp_t") == 0)
> +		return false;
>  
>  	return true;
>  }