[PATCH 3/9] tracing: Exclude 'generic fields' from histograms

From: Tom Zanussi
Date: Fri Sep 22 2017 - 15:59:08 EST


There are a small number of 'generic fields' (comm/COMM/cpu/CPU) that
are found by trace_find_event_field() but are only meant for
filtering. Specifically, they unlike normal fields, they have a size
of 0 and thus wreak havoc when used as a histogram key.

Exclude these (return -EINVAL) when used as histogram keys.

Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
---
kernel/trace/trace_events_hist.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1c21d0e..7eb975a 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -450,7 +450,7 @@ static int create_val_field(struct hist_trigger_data *hist_data,
}

field = trace_find_event_field(file->event_call, field_name);
- if (!field) {
+ if (!field || !field->size) {
ret = -EINVAL;
goto out;
}
@@ -548,7 +548,7 @@ static int create_key_field(struct hist_trigger_data *hist_data,
}

field = trace_find_event_field(file->event_call, field_name);
- if (!field) {
+ if (!field || !field->size) {
ret = -EINVAL;
goto out;
}
--
1.9.3