ftrace: Add default recursion protection for function tracing

As more users of the function tracer utility are being added, they do
not always add the necessary recursion protection. To protect from
function recursion due to tracing, if the callback ftrace_ops does not
specifically specify that it protects against recursion (by setting
the FTRACE_OPS_FL_RECURSION_SAFE flag), the list operation will be
called by the mcount trampoline which adds recursion protection.

If the flag is set, then the function will be called directly with no
extra protection.

Note, the list operation is called if more than one function callback
is registered, or if the arch does not support all of the function
tracer features.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 5675ebd541f0..fdff65dff1bb 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -153,13 +153,13 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
 static struct ftrace_ops trace_ops __read_mostly =
 {
         .func = function_trace_call,
-        .flags = FTRACE_OPS_FL_GLOBAL,
+        .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
 };
 
 static struct ftrace_ops trace_stack_ops __read_mostly =
 {
         .func = function_stack_trace_call,
-        .flags = FTRACE_OPS_FL_GLOBAL,
+        .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
 };
 
 /* Our two options */