Merge tag 'trace-v6.0-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...

[sfrench/cifs-2.6.git] / kernel / trace / ftrace.c

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index bc921a3f7ea894f975238c7d0319f1cbd94ec9c5..126c769d36c3cf48cf46bb495b96cf834662b5cc 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2974,6 +2974,16 @@ int ftrace_startup(struct ftrace_ops *ops, int command)
 
        ftrace_startup_enable(command);
 
+       /*
+        * If ftrace is in an undefined state, we just remove ops from list
+        * to prevent the NULL pointer, instead of totally rolling it back and
+        * free trampoline, because those actions could cause further damage.
+        */
+       if (unlikely(ftrace_disabled)) {
+               __unregister_ftrace_function(ops);
+               return -ENODEV;
+       }
+
        ops->flags &= ~FTRACE_OPS_FL_ADDING;
 
        return 0;