linux-kernel - Re: [PATCH] powerpc/highmem: change BUG_ON() to WARN

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Date:   Thu, 21 Mar 2019 21:07:35 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Christophe Leroy <christophe.leroy@....fr>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] powerpc/highmem: change BUG_ON() to WARN_ON()

Christophe Leroy <christophe.leroy@....fr> writes:

> Le 21/03/2019 à 06:29, Michael Ellerman a écrit :
>> Christophe Leroy <christophe.leroy@....fr> writes:
>>> In arch/powerpc/mm/highmem.c, BUG_ON() is called only when
>>> CONFIG_DEBUG_HIGHMEM is selected, this means the BUG_ON() is
>>> not vital and can be replaced by a a WARN_ON
>>>
>>> At the sametime, use IS_ENABLED() instead of #ifdef to clean a bit.
>>>
>>> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
>>> ---
>>>   arch/powerpc/mm/highmem.c | 12 ++++--------
>>>   1 file changed, 4 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/arch/powerpc/mm/highmem.c b/arch/powerpc/mm/highmem.c
>>> index 82a0e37557a5..b68c9f20fbdf 100644
>>> --- a/arch/powerpc/mm/highmem.c
>>> +++ b/arch/powerpc/mm/highmem.c
>>> @@ -56,7 +54,7 @@ EXPORT_SYMBOL(kmap_atomic_prot);
>>>   void __kunmap_atomic(void *kvaddr)
>>>   {
>>>   	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
>>> -	int type __maybe_unused;
>>> +	int type;
>> 
>> Why don't we move type into the block below.
>
> Yes you're right, when Mathieu introduced the __maybe_unused, I was 
> wrongly thinging that kmap_atomic_idx() was doing something important 
> that had to be done also when DEBUG was not selected, but indeed it does 
> nothing else than returning the type.
>
> I'll send a new patch.

I can just fix it up when applying.

cheers