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

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Date:   Thu, 26 Nov 2020 01:30:26 -0500
From:   Paul Gortmaker <paul.gortmaker@...driver.com>
To:     linux-kernel@...r.kernel.org
Cc:     Paul Gortmaker <paul.gortmaker@...driver.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        John Ogness <john.ogness@...utronix.de>
Subject: [PATCH 0/3] clear_warn_once: add timed interval resetting

The existing clear_warn_once functionality is currently a manually
issued state reset via the file /sys/kernel/debug/clear_warn_once when
debugfs is mounted.  The idea being that a developer would be running
some tests, like LTP or similar, and want to check reproducibility
without having to reboot.

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.

The functionality added here allows for periodic resets in addition to
the one-shot reset it already had.  Then we allow for a boot-time setting
of the periodic resets so it can be used even when debugfs isn't mounted.

By having a periodic reset, we also open the door for having the various
"once" functions act as long period ratelimited messages, where a sysadmin
can pick an hour or a day reset if they are facing an issue and are
wondering "did this just happen once, or am I only being informed once?"

Tested with DEBUG_FS_ALLOW_ALL and DEBUG_FS_ALLOW_NONE on an otherwise
defconfig.

---

Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Petr Mladek <pmladek@...e.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: John Ogness <john.ogness@...utronix.de>

Paul Gortmaker (3):
  clear_warn_once: expand debugfs to include read support
  clear_warn_once: bind a timer to written reset value
  clear_warn_once: add a warn_once_reset= boot parameter

 .../admin-guide/clearing-warn-once.rst        |  9 +++
 .../admin-guide/kernel-parameters.txt         |  8 ++
 kernel/panic.c                                | 78 +++++++++++++++++--
 3 files changed, 90 insertions(+), 5 deletions(-)

-- 
2.25.1