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>

1 files changed, 3 insertions, 3 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7968762c8167..1e6640f80454 100644
--- 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;
         }