linux-kernel - [PATCH 3.10 141/180] arc: unwind: warn only once if DW2

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Date:   Sun, 21 Aug 2016 17:31:11 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        Alexey Brodkin <abrodkin@...opsys.com>,
        Vineet Gupta <vgupta@...opsys.com>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 141/180] arc: unwind: warn only once if DW2_UNWIND is disabled

From: Alexey Brodkin <Alexey.Brodkin@...opsys.com>

commit 9bd54517ee86cb164c734f72ea95aeba4804f10b upstream.

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@...opsys.com>
Cc: stable@...r.kernel.org
Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
Signed-off-by: Willy Tarreau <w@....eu>
---
 arch/arc/kernel/stacktrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c
index ca0207b..06997ad 100644
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -131,7 +131,7 @@ 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
-- 
2.8.0.rc2.1.gbe9624a