tracing/kprobe: Fix handling of C-unlike argument names

Check the argument name whether it is invalid (not C-like symbol name). This
makes event format simple.

Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
LKML-Reference: <20100827113912.22882.62313.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

kernel/trace/trace_kprobe.c

@@ -514,8 +514,8 @@ static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
 				struct pt_regs *regs);
 
-/* Check the name is good for event/group */
-static int check_event_name(const char *name)
+/* Check the name is good for event/group/fields */
+static int is_good_name(const char *name)
 {
 	if (!isalpha(*name) && *name != '_')
 		return 0;
@@ -557,7 +557,7 @@ static struct trace_probe *alloc_trace_probe(const char *group,
 	else
 		tp->rp.kp.pre_handler = kprobe_dispatcher;
 
-	if (!event || !check_event_name(event)) {
+	if (!event || !is_good_name(event)) {
 		ret = -EINVAL;
 		goto error;
 	}
@@ -567,7 +567,7 @@ static struct trace_probe *alloc_trace_probe(const char *group,
 	if (!tp->call.name)
 		goto error;
 
-	if (!group || !check_event_name(group)) {
+	if (!group || !is_good_name(group)) {
 		ret = -EINVAL;
 		goto error;
 	}
@@ -883,7 +883,7 @@ static int create_trace_probe(int argc, char **argv)
 	int i, ret = 0;
 	int is_return = 0, is_delete = 0;
 	char *symbol = NULL, *event = NULL, *group = NULL;
-	char *arg, *tmp;
+	char *arg;
 	unsigned long offset = 0;
 	void *addr = NULL;
 	char buf[MAX_EVENT_NAME_LEN];
@@ -1012,9 +1012,13 @@ static int create_trace_probe(int argc, char **argv)
 			ret = -ENOMEM;
 			goto error;
 		}
-		tmp = strchr(tp->args[i].name, ':');
-		if (tmp)
-			*tmp = '_';	/* convert : to _ */
+
+		if (!is_good_name(tp->args[i].name)) {
+			pr_info("Invalid argument[%d] name: %s\n",
+				i, tp->args[i].name);
+			ret = -EINVAL;
+			goto error;
+		}
 
 		if (conflict_field_name(tp->args[i].name, tp->args, i)) {
 			pr_info("Argument[%d] name '%s' conflicts with "