arc: unwind: warn only once if DW2_UNWIND is disabled

If CONFIG_ARC_DW2_UNWIND is disabled every time arc_unwind_core()
gets called following message gets printed in debug console:
----------------->8---------------
CONFIG_ARC_DW2_UNWIND needs to be enabled
----------------->8---------------

That message makes sense if user indeed wants to see a backtrace or
get nice function call-graphs in perf but what if user disabled
unwinder for the purpose? Why pollute his debug console?

So instead we'll warn user about possibly missing feature once and
let him decide if that was what he or she really wanted.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: stable@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c
index e0efff15a5aece29f9bf8ca45b95f856fc206eab..b9192a653b7e3a2a2a34c8ddaed1dfad037f30c0 100644 (file)
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -142,7 +142,7 @@ arc_unwind_core(struct task_struct *tsk, struct pt_regs *regs,
         * prelogue is setup (callee regs saved and then fp set and not other
         * way around
         */
-       pr_warn("CONFIG_ARC_DW2_UNWIND needs to be enabled\n");
+       pr_warn_once("CONFIG_ARC_DW2_UNWIND needs to be enabled\n");
        return 0;
 
 #endif