[PATCH 1/3] parisc: don't use dereference_function_descriptor() in trace stub

[Sven Schnelle <svens@stackframe.org>]

dereference_function_descriptor() calls get_kernel_nofault(),
which itself might call into tracing. This leads to a deadlock.

Instead of reverting back to casts to compare whether there's
a trace function set, just always call the appropriate trace function.
With dynamic ftrace this function shouldn't be called at all
when ftrace is disabled. It adds a function call for the non-dynamic
case, but people concerned about the costs of ftrace should use
dynamic ftrace anyways.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 arch/parisc/kernel/ftrace.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c
index 0a1e75af5382..f5f467ebf94c 100644
--- a/arch/parisc/kernel/ftrace.c
+++ b/arch/parisc/kernel/ftrace.c
@@ -58,10 +58,7 @@ void notrace __hot ftrace_function_trampoline(unsigned long parent,
 #endif
 	extern struct ftrace_ops *function_trace_op;
 
-	if (function_trace_op->flags & FTRACE_OPS_FL_ENABLED &&
-	    ftrace_trace_function != ftrace_stub)
-		ftrace_trace_function(self_addr, parent,
-				function_trace_op, fregs);
+	ftrace_trace_function(self_addr, parent, function_trace_op, fregs);
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	if (dereference_function_descriptor(ftrace_graph_return) !=
@@ -101,6 +98,7 @@ int __init ftrace_dyn_arch_init(void)
 }
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
+	ftrace_trace_function = func;
 	return 0;
 }
 
-- 
2.33.0