Re: [PATCH 2/3] clear_warn_once: bind a timer to written reset value

[Steven Rostedt]

On Thu, 26 Nov 2020 01:30:28 -0500
Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx> wrote:

> +++ b/Documentation/admin-guide/clearing-warn-once.rst
> @@ -7,3 +7,12 @@ echo 1 > /sys/kernel/debug/clear_warn_once
>  
>  clears the state and allows the warnings to print once again.
>  This can be useful after test suite runs to reproduce problems.
> +
> +Values greater than one set a timer for a periodic state reset; e.g.
> +
> +echo 3600 > /sys/kernel/debug/clear_warn_once

I wonder if the value should be in minutes and not seconds, otherwise, a
wrong value could possibly DoS the machine, if you were to write 2 into it.
If there were a lot of warnings in high frequency events.

Or is dumping out a bunch of warnings every 2 seconds not be a problem?

Anyway, would there ever be a need to have it cleared in less than 1 minute
intervals?

-- Steve


> +
> +will establish an hourly state reset, effectively turning WARN_ONCE
> +into a long period rate-limited warning.