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From:   Kalle Valo <kvalo@kernel.org>
To:     David Hildenbrand <david@redhat.com>
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        Linus Torvalds <torvalds@linux-foundation.org>,
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        Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>
Subject: Re: [PATCH v1 1/3] coding-style.rst: document BUG() and WARN() rules ("do not crash the kernel")
References: <20220920122302.99195-1-david@redhat.com>
        <20220920122302.99195-2-david@redhat.com> <87pmfp8hnj.fsf@kernel.org>
        <d1ceedca-b28e-c47e-aa0d-aa1cb36d12b9@redhat.com>
Date:   Mon, 26 Sep 2022 10:44:23 +0300
In-Reply-To: <d1ceedca-b28e-c47e-aa0d-aa1cb36d12b9@redhat.com> (David
        Hildenbrand's message of "Thu, 22 Sep 2022 16:12:05 +0200")
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David Hildenbrand <david@redhat.com> writes:

>>> +Use WARN_ON_ONCE() rather than WARN() or WARN_ON()
>>> +**************************************************
>>> +
>>> +WARN_ON_ONCE() is generally preferred over WARN() or WARN_ON(), because it
>>> +is common for a given warning condition, if it occurs at all, to occur
>>> +multiple times. This can fill up and wrap the kernel log, and can even slow
>>> +the system enough that the excessive logging turns into its own, additional
>>> +problem.
>>
>> FWIW I have had cases where WARN() messages caused a reboot, maybe
>> mention that here? In my case the logging was so excessive that the
>> watchdog wasn't updated and in the end the device was forcefully
>> rebooted.
>>
>
> That should be covered by the last part, no? What would be your suggestion?

I was just thinking that maybe make it more obvious that even WARN_ON()
can crash the system, something along these lines:

"..., additional problem like stalling the system so much that it causes
a reboot."

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