tracing, alpha: undefined reference to `save_stack_trace'

Impact: build fix on !stacktrace architectures

only select STACKTRACE on architectures that have STACKTRACE_SUPPORT

... since we also need to ifdef out the guts of ftrace_trace_stack().
We also want to disallow setting TRACE_ITER_STACKTRACE in trace_flags
on such configs, but that can wait.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 3 insertions, 1 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index b58f43bec363..33dbefd471e8 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -25,7 +25,7 @@ config TRACING
         bool
         select DEBUG_FS
         select RING_BUFFER
-        select STACKTRACE
+        select STACKTRACE if STACKTRACE_SUPPORT
         select TRACEPOINTS
         select NOP_TRACER
 
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8a499e2adaec..85bee775a03e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -705,6 +705,7 @@ static void ftrace_trace_stack(struct trace_array *tr,
                                unsigned long flags,
                                int skip, int pc)
 {
+#ifdef CONFIG_STACKTRACE
         struct ring_buffer_event *event;
         struct stack_entry *entry;
         struct stack_trace trace;
@@ -730,6 +731,7 @@ static void ftrace_trace_stack(struct trace_array *tr,
 
         save_stack_trace(&trace);
         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
+#endif
 }
 
 void __trace_stack(struct trace_array *tr,