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

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Date:   Thu, 21 Mar 2019 16:29:59 +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:
> 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.

eg:

> @@ -66,12 +64,11 @@ void __kunmap_atomic(void *kvaddr)
>  
-  	type = kmap_atomic_idx();
>  
> -#ifdef CONFIG_DEBUG_HIGHMEM
> -	{
> +	if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM)) {
  		int type = kmap_atomic_idx();
>  		unsigned int idx;
>  
>  		idx = type + KM_TYPE_NR * smp_processor_id();
> -		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
> +		WARN_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));


cheers