linux-kernel - Re: [PATCH 2/3] panic: improve panic

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Date:	Mon, 11 Nov 2013 06:44:35 -0600
From:	Felipe Contreras <felipe.contreras@...il.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 2/3] panic: improve panic_timeout calculation

On Mon, Nov 11, 2013 at 5:32 AM, Ingo Molnar <mingo@...nel.org> wrote:
>
> * Felipe Contreras <felipe.contreras@...il.com> wrote:
>
>> We want to calculate the blinks per second, and instead of making it 5
>> (1000 / (3600 / 18)), let's make it 4, so the user can see two blinks
>> per second.
>
> Please use the customary changelog style we use in the kernel:
>
>   " Current code does (A), this has a problem when (B).
>     We can improve this doing (C), because (D)."

A is explained, B is empty, C is explained, D is because it makes sense.

>> Signed-off-by: Felipe Contreras <felipe.contreras@...il.com>
>> ---
>>  kernel/panic.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/kernel/panic.c b/kernel/panic.c
>> index 46e37ff..5a0bdaa 100644
>> --- a/kernel/panic.c
>> +++ b/kernel/panic.c
>> @@ -25,7 +25,7 @@
>>  #include <linux/nmi.h>
>>
>>  #define PANIC_TIMER_STEP 100
>> -#define PANIC_BLINK_SPD 18
>> +#define PANIC_BLINK_SPD 4
>
> Please while at it also do another patch that renames it to a sane name,
> PANIC_BLINK_SPEED or so.

If I can do that, I would rather use PANIC_BLINK_PER_SECOND.

>>  int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
>>  static unsigned long tainted_mask;
>> @@ -147,7 +147,7 @@ void panic(const char *fmt, ...)
>>                       touch_nmi_watchdog();
>>                       if (i >= i_next) {
>>                               i += panic_blink(state ^= 1);
>> -                             i_next = i + 3600 / PANIC_BLINK_SPD;
>> +                             i_next = i + 1000 / PANIC_BLINK_SPD;
>
> This changes a magic value to another magic value.

A magic value that is used all over the kernel, including
kernel/time.c and include/linux/delay.h. I'll change it to
MSEC_PER_SEC if that makes you happy.

-- 
Felipe Contreras
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