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Subject[for-next][PATCH 16/25] tracing: Fix issue of missing one synthetic field
From: Zheng Yejian <>

The maximum number of synthetic fields supported is defined as
SYNTH_FIELDS_MAX which value currently is 64, but it actually fails
when try to generate a synthetic event with 64 fields by executing like:

# echo "my_synth_event int v1; int v2; int v3; int v4; int v5; int v6;\
int v7; int v8; int v9; int v10; int v11; int v12; int v13; int v14;\
int v15; int v16; int v17; int v18; int v19; int v20; int v21; int v22;\
int v23; int v24; int v25; int v26; int v27; int v28; int v29; int v30;\
int v31; int v32; int v33; int v34; int v35; int v36; int v37; int v38;\
int v39; int v40; int v41; int v42; int v43; int v44; int v45; int v46;\
int v47; int v48; int v49; int v50; int v51; int v52; int v53; int v54;\
int v55; int v56; int v57; int v58; int v59; int v60; int v61; int v62;\
int v63; int v64" >> /sys/kernel/tracing/synthetic_events

Correct the field counting to fix it.


Cc: <>
Cc: <>
Fixes: c9e759b1e845 ("tracing: Rework synthetic event command parsing")
Signed-off-by: Zheng Yejian <>
Signed-off-by: Steven Rostedt (Google) <>
kernel/trace/trace_events_synth.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index c3b582d19b62..67592eed0be8 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -1282,12 +1282,12 @@ static int __create_synth_event(const char *name, const char *raw_fields)
goto err_free_arg;

- fields[n_fields++] = field;
if (n_fields == SYNTH_FIELDS_MAX) {
ret = -EINVAL;
goto err_free_arg;
+ fields[n_fields++] = field;


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