[PATCH v2 2/2] tracnig: Add proper error message for glob use with "within" filter

[Steven Rostedt <rostedt@kernel.org>]

From: Steven Rostedt <rostedt@goodmis.org>

If a user were to use a glob expression with the "within" filter, it
currently just fails with an errno return but does not update the
error_log to tell the user why it failed. Update it to use the parsing
error log to tell the user why it failed.

  # echo 'within ~ "*_read"' > events/kmem/kmem_cache_alloc/filter
  -bash: echo: write error: Invalid argument

  # cat error_log
  [ 4676.606481] event filter parse error: error: 'within' filter cannot take glob expressions
    Command: within ~ "*_read"
                              ^

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_events_filter.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 297bf156ea65..f811c527cce8 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -118,6 +118,7 @@ struct filter_pred {
 	C(IP_FIELD_ONLY,	"Only 'ip' field is supported for function trace"), \
 	C(INVALID_VALUE,	"Invalid value (did you forget quotes)?"), \
 	C(NO_FUNCTION,		"Function not found"),			\
+	C(GLOB_WITHIN,		"'within' filter cannot take glob expressions"), \
 	C(ERRNO,		"Error"),				\
 	C(NO_FILTER,		"No filter found")
 
@@ -2024,8 +2025,10 @@ static int parse_pred(const char *str, void *data,
 		} else if (field->filter_type == FILTER_WITHIN) {
 			unsigned long func;
 
-			if (op == OP_GLOB)
+			if (op == OP_GLOB) {
+				parse_error(pe, FILT_ERR_GLOB_WITHIN, pos + i);
 				goto err_free;
+			}
 
 			pred->fn_num = FILTER_PRED_FN_WITHIN;
 			func = kallsyms_lookup_name(pred->regex->pattern);
-- 
2.53.0