linux-kernel - Re: [PATCH 0/3] clear_warn_once: add timed interval resetting

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Date:   Mon, 30 Nov 2020 12:38:43 -0500
From:   Paul Gortmaker <paul.gortmaker@...driver.com>
To:     Andi Kleen <ak@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        John Ogness <john.ogness@...utronix.de>
Subject: Re: [PATCH 0/3] clear_warn_once: add timed interval resetting

[Re: [PATCH 0/3] clear_warn_once: add timed interval resetting] On 29/11/2020 (Sun 19:08) Andi Kleen wrote:

> On Thu, Nov 26, 2020 at 01:30:26AM -0500, Paul Gortmaker wrote:
> > But you currently can't make use of clear_warn_once unless you've got
> > debugfs enabled and mounted - which may not be desired by some people
> > in some deployment situations.
> 
> Seems awfully special purpose. The problem with debugfs is security,
> or is it no convenient process that could do cron like functionality? 

My understanding is that it is a bit of both.  As users of rt tasks,
they won't be running anything like cron that could add to OS jitter on
the (presumably minimal) rootfs - so they were looking for a clean
engineered solution with near zero overhead, that they could easily
deploy on all nodes after the rt tuning was 99% completed and node
images had been bundled.  Just to be sure everything was operating as
they'd aimed to achieve.

I thought a boot arg (and the internal timer) seemed like a good fit to
that requirement.  No kernel or rootfs rebuilding required.  And I
figured others might be in the same boat and could use it too.

Paul.
--

> 
> If it's the first, perhaps what they really need is a way to get
> a partial debugfs? 
> 
> -Andi