ftrace: Ignore FTRACE_FL_DISABLED while walking dyn_ftrace records

commit 977c1f9c8c022d0173181766b34a0db3705265a4 upstream.

ftrace_shutdown() checks for sanity of ftrace records
and if dyn_ftrace->flags is not zero, it will warn.
It can happen that 'flags' are set to FTRACE_FL_DISABLED at this point,
since some module was loaded, but before ftrace_module_enable()
cleared the flags for this module.

In other words the module.c is doing:
ftrace_module_init(mod); // calls ftrace_update_code() that sets flags=FTRACE_FL_DISABLED
... // here ftrace_shutdown() is called that warns, since
err = prepare_coming_module(mod); // didn't have a chance to clear FTRACE_FL_DISABLED

Fix it by ignoring disabled records.
It's similar to what __ftrace_hash_rec_update() is already doing.

Link: http://lkml.kernel.org/r/1478560460-3818619-1-git-send-email-ast@fb.com
Fixes: b7ffffbb46f2 "ftrace: Add infrastructure for delayed enabling of module functions"
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 84752c8e28b5286b03d9422a79a92429427681cb..fb26c78309aa437996ff9c3edf4714c6ed0c3024 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2757,7 +2757,7 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
                struct dyn_ftrace *rec;
 
                do_for_each_ftrace_rec(pg, rec) {
-                       if (FTRACE_WARN_ON_ONCE(rec->flags))
+                       if (FTRACE_WARN_ON_ONCE(rec->flags & ~FTRACE_FL_DISABLED))
                                pr_warn("  %pS flags:%lx\n",
                                        (void *)rec->ip, rec->flags);
                } while_for_each_ftrace_rec();