Re: [PATCH] powerpc/highmem: change BUG_ON() to WARN_ON()

[Christophe Leroy]

Le 21/03/2019 Ã 06:29, Michael Ellerman a ÃcritÂ:
> Christophe Leroy <christophe.leroy@xxxxxx> 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@xxxxxx>
> > ---
> >   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.

Christophe

> 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