[SLOF] [PATCH slof] fdt: Avoid recursion when traversing tree

[Greg Kurz]

Hi Alexey,

It seems it did again ! I haven't received this in my inbox, despite you've
put me on Cc... :-\

On Thu, 16 Jul 2020 14:55:42 +1000
Alexey Kardashevskiy <aik at ozlabs.ru> wrote:

> A loop over peers does not need recursion which becomes a problem with
> hundreds devices.
> 

You're likely right but, per curiosity, do you have some numbers to
share ?

> Cc: Greg Kurz <groug at kaod.org>
> Fixes: efa56b851fab ("fdt: Delete nodes of devices removed between boot and CAS")
> Suggested-by: Jordan Niethe <jniethe5 at gmail.com>
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> ---
>  board-qemu/slof/fdt.fs | 27 +++++++++++++++------------
>  1 file changed, 15 insertions(+), 12 deletions(-)
> 
> diff --git a/board-qemu/slof/fdt.fs b/board-qemu/slof/fdt.fs
> index 7da4ff066702..03b1d4034d0a 100644
> --- a/board-qemu/slof/fdt.fs
> +++ b/board-qemu/slof/fdt.fs
> @@ -636,20 +636,23 @@ r> drop
>      THEN
>  ;
>  
> -: (fdt-cas-search-obsolete-nodes) ( start node -- )
> -    dup IF
> -	dup child 2 pick swap recurse
> -	dup peer 2 pick swap recurse
> -
> -	dup fdt-cas-node-obsolete? IF
> -	    fdt-debug IF dup ." Deleting obsolete node: " dup .node ." = " . cr THEN
> -	    dup delete-node
> -	THEN
> +: (fdt-cas-search-obsolete-nodes) ( node -- )
> +    dup child
> +    BEGIN
> +	dup
> +    WHILE
> +	dup recurse
> +	peer
> +    REPEAT
> +    drop
> +    dup fdt-cas-node-obsolete? IF
> +        fdt-debug IF dup ." Deleting obsolete node: " dup .node ." = " . cr THEN
> +        dup delete-node
>      THEN
> -    2drop
> +    drop
>  ;
>  
> -: fdt-cas-delete-obsolete-nodes ( start -- )
> +: fdt-cas-delete-obsolete-nodes ( -- )
>      s" /" find-device get-node (fdt-cas-search-obsolete-nodes)
>      fdt-cas-delete-obsolete-aliases
>  ;
> @@ -657,7 +660,7 @@ r> drop
>  : fdt-fix-cas-node ( start -- )
>      fdt-generation# 1+ to fdt-generation#
>      0 to fdt-cas-pass dup (fdt-fix-cas-node) drop \ Add phandles
> -    dup fdt-cas-delete-obsolete-nodes             \ Delete removed devices
> +    fdt-cas-delete-obsolete-nodes             \ Delete removed devices

Maybe keep the comment aligned with the other ones ?

Reviewed-by: Greg Kurz <groug at kaod.org>

>      1 to fdt-cas-pass dup (fdt-fix-cas-node) drop \ Patch+add other properties
>      2 to fdt-cas-pass dup (fdt-fix-cas-node) drop \ Delete phandles from pass 0
>      drop