[PATCH] arc: warn only once if DW2_UNWIND is disabled

[PATCH] arc: warn only once if DW2_UNWIND is disabled

[Alexey Brodkin]

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  [3.18+]
---
 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 e0efff1..b9192a6 100644
--- 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
-- 
2.5.5

Re: [PATCH] arc: warn only once if DW2_UNWIND is disabled

[Vineet Gupta]

On Thursday 23 June 2016 01:30 PM, Alexey Brodkin wrote:
> 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  [3.18+]

Does this really need to be stable backport ?

> ---
>  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 e0efff1..b9192a6 100644
> --- 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
> 

Re: [PATCH] arc: warn only once if DW2_UNWIND is disabled

[Alexey Brodkin]

Hi Vineet,

On Tue, 2016-06-28 at 10:00 +0530, Vineet Gupta wrote:
> On Thursday 23 June 2016 01:30 PM, Alexey Brodkin wrote:
> > 
> > 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  [3.18+]
>
> Does this really need to be stable backport ?

I think it makes perfect sense for any kernel version because
it saves debug console from being polluted with messages which
most probably have no point (Ok I disabled unwinder in kernel config,
why then spam me with proposals to enable it)?

-Alexey