Re: [PATCH] powerpc/kexec: Simplify kdump_extra_elfcorehdr_size()

[Thorsten Blum <thorsten.blum@linux.dev>]

On Thu, Jul 30, 2026 at 04:33:18PM +0200, Christophe Leroy (CS GROUP) wrote:
> Le 30/07/2026 à 15:19, Thorsten Blum a écrit :
> > Return the size directly and drop the extra_sz variable to simplify
> > kdump_extra_elfcorehdr_size(). The two warning paths now fall through
> > to the existing return 0 at the end of the function.
> > 
> > Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> > ---
> >   arch/powerpc/kexec/file_load_64.c | 6 +-----
> >   1 file changed, 1 insertion(+), 5 deletions(-)
> > 
> > diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
> > index c3503d698428..d0c544079e03 100644
> > --- a/arch/powerpc/kexec/file_load_64.c
> > +++ b/arch/powerpc/kexec/file_load_64.c
> > @@ -377,16 +377,12 @@ static int load_backup_segment(struct kimage *image, struct kexec_buf *kbuf)
> >   static unsigned int kdump_extra_elfcorehdr_size(struct crash_mem *cmem)
> >   {
> >   #if defined(CONFIG_CRASH_HOTPLUG) && defined(CONFIG_MEMORY_HOTPLUG)
> > -	unsigned int extra_sz = 0;
> > -
> >   	if (CONFIG_CRASH_MAX_MEMORY_RANGES > (unsigned int)PN_XNUM)
> >   		pr_warn("Number of Phdrs %u exceeds max\n", CONFIG_CRASH_MAX_MEMORY_RANGES);
> >   	else if (cmem->nr_ranges >= CONFIG_CRASH_MAX_MEMORY_RANGES)
> >   		pr_warn("Configured crash mem ranges may not be enough\n");
> >   	else
> > -		extra_sz = (CONFIG_CRASH_MAX_MEMORY_RANGES - cmem->nr_ranges) * sizeof(Elf64_Phdr);
> > -
> > -	return extra_sz;
> > +		return (CONFIG_CRASH_MAX_MEMORY_RANGES - cmem->nr_ranges) * sizeof(Elf64_Phdr);
> 
> I don't understand.
> 
> Previously, when cmem->nr_ranges >= CONFIG_CRASH_MAX_MEMORY_RANGES you would
> return 0. Now you will return something different. For instance if
> cmem->nr_ranges is (CONFIG_CRASH_MAX_MEMORY_RANGES + 1) you will return
> (unsigned int)(-1 * sizeof(Elf64_Phdr))

It still returns 0.

When cmem->nr_ranges >= CONFIG_CRASH_MAX_MEMORY_RANGES, the else if
branch prints the warning and then falls through to the return 0 at the
end of the function. The final else branch is not entered in that case.

No functional changes are intended.

> >   #endif
> >   	return 0;
> >   }
>