Re: [PATCH 02/12] kho: store incoming radix tree in kho_in

[Mike Rapoport <rppt@kernel.org>]

On Wed, Apr 29, 2026 at 03:39:04PM +0200, Pratyush Yadav wrote:
> From: "Pratyush Yadav (Google)" <pratyush@kernel.org>
> 
> This allows other functions to also use the radix tree. While at it,
> also use kho_get_mem_map_phys() instead of duplicating the code to get
> the radix tree root from the FDT.
> 
> Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
> ---
>  kernel/liveupdate/kexec_handover.c | 27 ++++++++-------------------
>  1 file changed, 8 insertions(+), 19 deletions(-)
> 
> diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
> index ba568d34c5b4..5758dc6fab5d 100644
> --- a/kernel/liveupdate/kexec_handover.c
> +++ b/kernel/liveupdate/kexec_handover.c
> @@ -1294,6 +1294,7 @@ struct kho_in {
>  	char previous_release[__NEW_UTS_LEN + 1];
>  	u32 kexec_count;
>  	struct kho_debugfs dbg;
> +	struct kho_radix_tree radix_tree;
>  };
>  
>  static struct kho_in kho_in = {
> @@ -1373,24 +1374,10 @@ EXPORT_SYMBOL_GPL(kho_retrieve_subtree);
>  
>  static int __init kho_mem_retrieve(const void *fdt)
>  {
> -	struct kho_radix_tree tree;
> -	const phys_addr_t *mem;
> -	int len;
> -
> -	/* Retrieve the KHO radix tree from passed-in FDT. */
> -	mem = fdt_getprop(fdt, 0, KHO_FDT_MEMORY_MAP_PROP_NAME, &len);
> -
> -	if (!mem || len != sizeof(*mem)) {
> -		pr_err("failed to get preserved KHO memory tree\n");
> -		return -ENOENT;
> -	}
> -
> -	if (!*mem)
> -		return -EINVAL;
> -
> -	tree.root = phys_to_virt(*mem);
> -	mutex_init(&tree.lock);
> -	return kho_radix_walk_tree(&tree, kho_preserved_memory_reserve);
> +	kho_in.radix_tree.root = phys_to_virt(kho_get_mem_map_phys(fdt));

Do we really want to remove an explicit check for 0 and get a WARN() in
kho_radix_walk_tree()?

> +	mutex_init(&kho_in.radix_tree.lock);
> +	return kho_radix_walk_tree(&kho_in.radix_tree,
> +				   kho_preserved_memory_reserve);
>  }
>  
>  static __init int kho_out_fdt_setup(void)
> @@ -1597,8 +1584,10 @@ void __init kho_memory_init(void)
>  	if (kho_in.scratch_phys) {
>  		kho_scratch = phys_to_virt(kho_in.scratch_phys);
>  
> -		if (kho_mem_retrieve(kho_get_fdt()))
> +		if (kho_mem_retrieve(kho_get_fdt())) {
>  			kho_in.fdt_phys = 0;
> +			kho_in.radix_tree.root = NULL;

I'd make kho_mem_retrieve() void and put these there.

> +		}
>  	} else {
>  		kho_reserve_scratch();
>  	}
> -- 
> 2.54.0.545.g6539524ca2-goog
> 

-- 
Sincerely yours,
Mike.