ftrace: Fix MATCH_END_ONLY function filter

For '*foo' pattern, we should allow any string ending with
'foo', but ftrace filter incorrectly disallows strings
like bar_foo_foo:

  # echo '*io' > set_ftrace_filter
  # cat set_ftrace_filter | grep 'req_bio_endio'
  # cat available_filter_functions | grep 'req_bio_endio'
  req_bio_endio

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4B4E870E.6060607@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7968762c8167062d1f05d2e14531b349ba840518..1e6640f80454000de4155a81a6c32a2f46816830 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1690,7 +1690,7 @@ ftrace_regex_lseek(struct file *file, loff_t offset, int origin)
 static int ftrace_match(char *str, char *regex, int len, int type)
 {
        int matched = 0;
-       char *ptr;
+       int slen;
 
        switch (type) {
        case MATCH_FULL:
@@ -1706,8 +1706,8 @@ static int ftrace_match(char *str, char *regex, int len, int type)
                        matched = 1;
                break;
        case MATCH_END_ONLY:
-               ptr = strstr(str, regex);
-               if (ptr && (ptr[len] == 0))
+               slen = strlen(str);
+               if (slen >= len && memcmp(str + slen - len, regex, len) == 0)
                        matched = 1;
                break;
        }