Subject: Re: [PATCH v2 5/6] arch: simplify several early memory allocations

From: Sam Ravnborg <[email-masked]>
Date: Thu, 6 Dec 2018 19:08:26 +0100

On Mon, Dec 03, 2018 at 06:49:21PM +0200, Mike Rapoport wrote:
> On Mon, Dec 03, 2018 at 05:29:08PM +0100, Sam Ravnborg wrote:
> > Hi Mike.
> > 
> > > index c37955d..2a17665 100644
> > > --- a/arch/sparc/kernel/prom_64.c
> > > +++ b/arch/sparc/kernel/prom_64.c
> > > @@ -34,16 +34,13 @@
> > >  
> > >  void * __init prom_early_alloc(unsigned long size)
> > >  {
> > > -	unsigned long paddr = memblock_phys_alloc(size, SMP_CACHE_BYTES);
> > > -	void *ret;
> > > +	void *ret = memblock_alloc(size, SMP_CACHE_BYTES);
> > >  
> > > -	if (!paddr) {
> > > +	if (!ret) {
> > >  		prom_printf("prom_early_alloc(%lu) failed\n", size);
> > >  		prom_halt();
> > >  	}
> > >  
> > > -	ret = __va(paddr);
> > > -	memset(ret, 0, size);
> > >  	prom_early_allocated += size;
> > >  
> > >  	return ret;
> > 
> > memblock_alloc() calls memblock_alloc_try_nid().
> > And if allocation fails then memblock_alloc_try_nid() calls panic().
> > So will we ever hit the prom_halt() code?
> 
> memblock_phys_alloc_try_nid() also calls panic if an allocation fails. So
> in either case we never reach prom_halt() code.

So we have code here we never reach - not nice.
If the idea is to avoid relying on the panic inside memblock_alloc() then
maybe replace it with a variant that do not call panic?
To make it clear what happens.

	Sam