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

Sam Ravnborg
2018-12-06T18:08:49Z

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