get_hist_field_flags() returns "stacktrace" for any field carrying
HIST_FIELD_FL_STACKTRACE, including the common_stacktrace pseudo-field,
which has no ftrace_event_field behind it. parse_field() no longer takes
the modifier there:
if (stack_modifier &&
(!field || field->filter_type != FILTER_STACKTRACE)) {
hist_err(tr, HIST_ERR_BAD_FIELD_MODIFIER, errpos(field_str));
so expr_field_str() renders "common_stacktrace.stacktrace", a spelling
that cannot be parsed back.
Report the modifier only when there is a field to report it for.
hist_field_print(), the other caller of get_hist_field_flags(), excludes
HIST_FIELD_FL_STACKTRACE before it calls, so this is confined to
expr_field_str(), whose only key renderer arrives in the next patch.
Fixes: a5e70ba87ca8 ("tracing: Fix memory corruption from the histogram
stacktrace modifier")
Signed-off-by: Donggeun Yoo <[email protected]>
Assisted-by: Claude:claude-fable-5
---
kernel/trace/trace_events_hist.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 91a550411e8a..fdd097abb0d6 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1725,7 +1725,7 @@ static const char *get_hist_field_flags(struct hist_field
*hist_field)
flags_str = "percent";
else if (hist_field->flags & HIST_FIELD_FL_GRAPH)
flags_str = "graph";
- else if (hist_field->flags & HIST_FIELD_FL_STACKTRACE)
+ else if (hist_field->flags & HIST_FIELD_FL_STACKTRACE &&
hist_field->field)
flags_str = "stacktrace";
return flags_str;
--
2.53.0
