tracing/filters: Use a different op for glob match

"==" will always do a full match, and "~" will do a glob match.

In the future, we may add "=~" for regex match.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <4AD69528.3050309@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/trace/trace.h

@@ -702,7 +702,7 @@ typedef int (*filter_pred_fn_t) (struct filter_pred *pred, void *event,
 typedef int (*regex_match_func)(char *str, struct regex *r, int len);
 
 enum regex_type {
-	MATCH_FULL,
+	MATCH_FULL = 0,
 	MATCH_FRONT_ONLY,
 	MATCH_MIDDLE_ONLY,
 	MATCH_END_ONLY,

kernel/trace/trace_events_filter.c

@@ -29,6 +29,7 @@ enum filter_op_ids
 {
 	OP_OR,
 	OP_AND,
+	OP_GLOB,
 	OP_NE,
 	OP_EQ,
 	OP_LT,
@@ -48,6 +49,7 @@ struct filter_op {
 static struct filter_op filter_ops[] = {
 	{ OP_OR,	"||",		1 },
 	{ OP_AND,	"&&",		2 },
+	{ OP_GLOB,	"~",		4 },
 	{ OP_NE,	"!=",		4 },
 	{ OP_EQ,	"==",		4 },
 	{ OP_LT,	"<",		5 },
@@ -329,22 +331,18 @@ enum regex_type filter_parse_regex(char *buff, int len, char **search, int *not)
 	return type;
 }
 
-static int filter_build_regex(struct filter_pred *pred)
+static void filter_build_regex(struct filter_pred *pred)
 {
 	struct regex *r = &pred->regex;
-	char *search, *dup;
-	enum regex_type type;
-	int not;
+	char *search;
+	enum regex_type type = MATCH_FULL;
+	int not = 0;
 
+	if (pred->op == OP_GLOB) {
 		type = filter_parse_regex(r->pattern, r->len, &search, &not);
-	dup = kstrdup(search, GFP_KERNEL);
-	if (!dup)
-		return -ENOMEM;
-
-	strcpy(r->pattern, dup);
-	kfree(dup);
-
-	r->len = strlen(r->pattern);
+		r->len = strlen(search);
+		memmove(r->pattern, search, r->len+1);
+	}
 
 	switch (type) {
 	case MATCH_FULL:
@@ -362,8 +360,6 @@ static int filter_build_regex(struct filter_pred *pred)
 	}
 
 	pred->not ^= not;
-
-	return 0;
 }
 
 /* return 1 if event matches, 0 otherwise (discard) */
@@ -676,7 +672,10 @@ static bool is_string_field(struct ftrace_event_field *field)
 
 static int is_legal_op(struct ftrace_event_field *field, int op)
 {
-	if (is_string_field(field) && (op != OP_EQ && op != OP_NE))
+	if (is_string_field(field) &&
+	    (op != OP_EQ && op != OP_NE && op != OP_GLOB))
+		return 0;
+	if (!is_string_field(field) && op == OP_GLOB)
 		return 0;
 
 	return 1;
@@ -761,9 +760,7 @@ static int filter_add_pred(struct filter_parse_state *ps,
 	}
 
 	if (is_string_field(field)) {
-		ret = filter_build_regex(pred);
-		if (ret)
-			return ret;
+		filter_build_regex(pred);
 
 		if (field->filter_type == FILTER_STATIC_STRING) {
 			fn = filter_pred_string;