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>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0118979..b532e4a 100644 (file)
--- 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);