[PATCH 7.1 068/228] ftrace: Protect direct_functions in ftrace_find_rec_direct

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Leon Hwang <[email protected]>

commit 63444b7617c09aeed36282e061c3f80818f2b600 upstream.

Fix accessing the __rcu pointer direct_functions with RCU protection.

Cc: [email protected]
Link: https://patch.msgid.link/[email protected]
Fixes: d05cb470663a ("ftrace: Fix modification of direct_function hash while in use")
Acked-by: Jiri Olsa <[email protected]>
Suggested-by: Steven Rostedt <[email protected]>
Signed-off-by: Leon Hwang <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 kernel/trace/ftrace.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2627,7 +2627,8 @@ unsigned long ftrace_find_rec_direct(uns
 {
 	struct ftrace_func_entry *entry;
 
-	entry = __ftrace_lookup_ip(direct_functions, ip);
+	guard(preempt_notrace)();
+	entry = __ftrace_lookup_ip(rcu_dereference_sched(direct_functions), ip);
 	if (!entry)
 		return 0;