tracing: Set kernel_stack's caller size properly

stable inclusion
from linux-4.19.149
commit 72913876dc5fe6ae97963b5674c1797b19f6efcd

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

[ Upstream commit cbc3b92c ]

I noticed when trying to use the trace-cmd python interface that reading the raw
buffer wasn't working for kernel_stack events.  This is because it uses a
stubbed version of __dynamic_array that doesn't do the __data_loc trick and
encode the length of the array into the field.  Instead it just shows up as a
size of 0.  So change this to __array and set the len to FTRACE_STACK_ENTRIES
since this is what we actually do in practice and matches how user_stack_trace
works.

Link: http://lkml.kernel.org/r/1411589652-1318-1-git-send-email-jbacik@fb.comSigned-off-by: NJosef Bacik <jbacik@fb.com>
[ Pulled from the archeological digging of my INBOX ]
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

kernel/trace/trace_entries.h

@@ -179,7 +179,7 @@ FTRACE_ENTRY(kernel_stack, stack_entry,
 
 	F_STRUCT(
 		__field(	int,		size	)
-		__dynamic_array(unsigned long,	caller	)
+		__array(	unsigned long,	caller,	FTRACE_STACK_ENTRIES	)
 	),
 
 	F_printk("\t=> (" IP_FMT ")\n\t=> (" IP_FMT ")\n\t=> (" IP_FMT ")\n"