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1/3 [
Author: Paul Gortmaker
Email: paul.gortmaker@windriver.com
Subject: clear_warn_once: expand debugfs to include read support
Date: Wed, 16 Dec 2020 12:22:56 -0500
The existing clear_warn_once variable is write-only; used as per the
documentation to reset the warn_once to as-booted state with:
echo 1 > /sys/kernel/debug/clear_warn_once
The objective is to expand on that functionality, which requires the
debugfs variable to be read/write and not just write-only.
Here, we deal with the debugfs boilerplate associated with converting
it from write-only to read-write, in order to factor that out for easier
review, and for what may be a possible future useful bisect point.
Existing functionality is unchanged - the only difference is that we
have tied in a variable that lets you now read the variable and see
the last value written.
Link: https://lore.kernel.org/r/20201126063029.2030-1-paul.gortmaker@windriver.com
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
]
2/3 [
Author: Paul Gortmaker
Email: paul.gortmaker@windriver.com
Subject: clear_warn_once: bind a timer to written reset value
Date: Wed, 16 Dec 2020 12:22:57 -0500
Existing documentation has a write of "1" to clear/reset all the
WARN_ONCE and similar to the as-booted state, so they can possibly
be re-triggered again during debugging/testing.
But having them auto-reset once a day, or once a week, might shed
valuable information to a sysadmin on what the system is doing while
trying to debug an issue.
Here we extend the existing debugfs variable to bind a timer to the
written value N, so that it will reset every N minutes, for N>1.
Writing a zero will clear any previously set timer value.
The pre-existing behaviour of writing N=1 will do a one-shot clear.
Link: https://lore.kernel.org/r/20201126063029.2030-1-paul.gortmaker@windriver.com
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
]
3/3 [
Author: Paul Gortmaker
Email: paul.gortmaker@windriver.com
Subject: clear_warn_once: add a clear_warn_once= boot parameter
Date: Wed, 16 Dec 2020 12:22:58 -0500
In the event debugfs is not mounted, or if built with the .config
setting DEBUG_FS_ALLOW_NONE chosen, this gives the sysadmin access
to reset the WARN_ONCE() state on a periodic basis.
Link: https://lore.kernel.org/r/20201126063029.2030-1-paul.gortmaker@windriver.com
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
]
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
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Bruce Ashfield