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SubjectRe: [PATCH v10 03/14] powerpc, kexec_file: factor out memblock-based arch_kexec_walk_mem()
James,

On Tue, Jul 03, 2018 at 05:36:24PM +0100, James Morse wrote:
> Hi Akashi,
>
> On 23/06/18 03:20, AKASHI Takahiro wrote:
> > Memblock list is another source for usable system memory layout.
> > A merged new arch_kexec_walk_mem() will walk through either io resource
> > list or memblock list depending on CONFIG_ARCH_DISCARD_MEMBLOCK so that
> > arm64, in addition to powerpc, will be able to utilize this generic
> > function for kexec_file.
>
> > diff --git a/arch/powerpc/kernel/machine_kexec_file_64.c b/arch/powerpc/kernel/machine_kexec_file_64.c
> > index 0bd23dc789a4..3d4be91786ce 100644
> > --- a/arch/powerpc/kernel/machine_kexec_file_64.c
> > +++ b/arch/powerpc/kernel/machine_kexec_file_64.c
>
> Does this file still need its memblock.h include?

OK. Will remove it.

>
> > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> > index 63c7ce1c0c3e..563acd1c9a61 100644
> > --- a/kernel/kexec_file.c
> > +++ b/kernel/kexec_file.c
> > @@ -16,6 +16,7 @@
> > #include <linux/file.h>
> > #include <linux/slab.h>
> > #include <linux/kexec.h>
> > +#include <linux/memblock.h>
> > #include <linux/mutex.h>
> > #include <linux/list.h>
> > #include <linux/fs.h>
> > @@ -501,6 +502,53 @@ static int locate_mem_hole_callback(struct resource *res, void *arg)
> > return locate_mem_hole_bottom_up(start, end, kbuf);
> > }
> >
> > +#if defined(CONFIG_HAVE_MEMBLOCK) && !defined(CONFIG_ARCH_DISCARD_MEMBLOCK)
>
> The only caller is also guarded by these same ifdefs. Can't we remove this and
> rely on the compilers dead-code elimination to remove this function when its not
> needed?

I don't think we can remove this #ifdef.
"for_each_free_mem_range[_reverse]()" is defined under CONFIG_HAVE_MEMBLOCK
in memblock.h. If some architecture wants to support KEXEC_FILE but
doesn't have HAVE_MEMBLOCK, compiling kexec_file.c will fail.

>
> > +static int kexec_walk_memblock(struct kexec_buf *kbuf,
> > + int (*func)(struct resource *, void *))
> > +{
> > + u64 i;
> > + phys_addr_t mstart, mend;
> > + struct resource res = { };
> > + int ret = 0;
>
>
> Keeping this patch as 'just' moving code would avoid having to play
> spot-the-difference:

OK. I will split this patch into two.
But just "moving" is impossible because the function names will be
duplicated in kexec_file.c.

> > + if (kbuf->image->type == KEXEC_TYPE_CRASH)
> > + return func(&crashk_res, kbuf);
>
> This will be new for powerpc, but any attempt to use it should be caught by
> arch_kexec_kernel_image_probe(), which has:
> | /* We don't support crash kernels yet. */
> | if (image->type == KEXEC_TYPE_CRASH)
> | return -EOPNOTSUPP;
>
>
> Looks good to me! For what its worth:
> Acked-by: James Morse <james.morse@arm.com>

Thank you for your reviews.

-Takahiro AKASHI

>
> Thanks,
>
> James

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