perf tools: Add file_only config option to strlist

If strlist_config.dirname is present, the strlist__new() tries to load
stirngs from dirname/list file first but if it failes it falls back to
add 'list' as string. But sometimes it's not desired so adds new
file_only field to prevent it.

Signed-off-by: Namhyung Kim <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
[ Add documentation for strlist_config::file_only, in the struct definition */
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/strlist.c

···
 			err = strlist__load(slist, subst);
 			goto out;
 		}
+
+		if (slist->file_only) {
+			err = -ENOENT;
+			goto out;
+		}
 	}
 
 	err = strlist__add(slist, s);
···
 
 	if (slist != NULL) {
 		bool dupstr = true;
+		bool file_only = false;
 		const char *dirname = NULL;
 
 		if (config) {
 			dupstr = !config->dont_dupstr;
 			dirname = config->dirname;
+			file_only = config->file_only;
 		}
 
 		rblist__init(&slist->rblist);
···
 		slist->rblist.node_delete = strlist__node_delete;
 
 		slist->dupstr	 = dupstr;
+		slist->file_only = file_only;
 
 		if (list && strlist__parse_list(slist, list, dirname) != 0)
 			goto out_error;

tools/perf/util/strlist.h

···
 
 struct strlist {
 	struct rblist rblist;
-	bool	       dupstr;
+	bool	      dupstr;
+	bool	      file_only;
 };
 
+/*
+ * @file_only: When dirname is present, only consider entries as filenames,
+ *             that should not be added to the list if dirname/entry is not
+ *             found
+ */
 struct strlist_config {
 	bool dont_dupstr;
+	bool file_only;
 	const char *dirname;
 };