ftrace: fix "notrace" filtering priority

This is a fix to give notrace filter rules priority over "set_ftrace_filter"
rules.

This fix ensures that functions which are set to be filtered and are
concurrently marked as "notrace" don't get recorded. As of now, if
a record is marked as FTRACE_FL_FILTER and is enabled, then the notrace
flag is not checked. Tested on x86-32.

Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 9 insertions, 3 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0118979e211f..b532e4a68c74 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -355,20 +355,26 @@ __ftrace_replace_code(struct dyn_ftrace *rec,
                  * If this record is set not to trace then
                  * do nothing.
                  *
+                 * If this record is set not to trace and
+                 * it is enabled then disable it.
+                 *
                  * If this record is not set to be filtered and
                  * it is enabled, disable it.
                  */
-                fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_ENABLED);
+
+                fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_NOTRACE |
+                                   FTRACE_FL_ENABLED);
 
                 if ((fl ==  (FTRACE_FL_FILTER | FTRACE_FL_ENABLED)) ||
-                    (fl == 0) || (rec->flags & FTRACE_FL_NOTRACE))
+                    (fl ==  (FTRACE_FL_FILTER | FTRACE_FL_NOTRACE)) ||
+                    !fl || (fl == FTRACE_FL_NOTRACE))
                         return 0;
 
                 /*
                  * If it is enabled disable it,
                  * otherwise enable it!
                  */
-                if (fl == FTRACE_FL_ENABLED) {
+                if (fl & FTRACE_FL_ENABLED) {
                         /* swap new and old */
                         new = old;
                         old = ftrace_call_replace(ip, FTRACE_ADDR);