[SLOF] [PATCH v2] fdt: Delete nodes of devices removed between boot and CAS

[Alexey Kardashevskiy]

On 11/02/2020 00:16, Greg Kurz wrote:
> We recently fixed node creation at CAS in order to support early hotplug
> of devices between boot and CAS. Let's handle node removal now to support
> early hot *un*plug of devices.
> 
> This is achieved by associating a generation number to each FDT received
> from QEMU and tagging all nodes with this number in a "slof,from-fdt"
> property. The generation number is kept in the fdt-generation# variable.
> It starts at 0 for the initial boot time FDT, and it is incremented at
> each subsequent CAS. All boot time nodes hence get "slof,from-fdt" == 0,
> all nodes present at CAS get "slof,from-fdt" == 1 and so on in case the
> guest calls CAS again. If a device gets hot unplugged before quiesce, we
> hence can detect it doesn't have the right generation number and thus
> delete the node from the DT. Note that this only affects nodes coming
> from the FDT. Nodes created by SLOF don't have the "slof,from-fdt"
> property, and therefore cannot be candidates to deletion.
> 
> Signed-off-by: Greg Kurz <groug at kaod.org>
> ---
> v2: - global rewrite using a generation number which gets copied to
>       a "slof,from-fdt" property
>     - delete aliases in a separate loop



Thanks, applied.



> ---
>  board-qemu/slof/fdt.fs |   72 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 72 insertions(+)
> 
> diff --git a/board-qemu/slof/fdt.fs b/board-qemu/slof/fdt.fs
> index 66f8fe74d9dd..6a694c17517a 100644
> --- a/board-qemu/slof/fdt.fs
> +++ b/board-qemu/slof/fdt.fs
> @@ -13,6 +13,11 @@
>  1 VALUE fdt-debug
>  TRUE VALUE fdt-cas-fix?
>  0 VALUE fdt-cas-pass
> +0 VALUE fdt-generation#
> +
> +: fdt-update-from-fdt ( -- )
> +  fdt-generation# encode-int s" slof,from-fdt" property
> +;
>  
>  \ Bail out if no fdt
>  fdt-start 0 = IF -1 throw THEN
> @@ -198,6 +203,8 @@ fdt-check-header
>      decode-int dup fdt-create-dec fdt-create-enc 2drop
>    THEN
>  
> +  fdt-update-from-fdt
> +
>    finish-device  
>  ;
>  
> @@ -514,6 +521,9 @@ r> drop
>      swap			( newnode? a1 )
>  
>      fdt-debug IF ." Current  now: " pwd  get-node ."  = " . cr THEN
> +    fdt-cas-pass 0= IF
> +	fdt-update-from-fdt
> +    THEN
>      BEGIN
>  	fdt-next-tag dup OF_DT_END_NODE <>
>      WHILE
> @@ -584,8 +594,70 @@ r> drop
>      THEN
>  ;
>  
> +: alias-dev-path ( xt -- dev-path len )
> +    link> execute decode-string	2swap 2drop
> +;
> +
> +: alias-name ( xt -- alias-name len )
> +    link> >name name>string
> +;
> +
> +: fdt-cas-alias-obsolete? ( xt -- true|false )
> +    alias-dev-path find-node 0=
> +;
> +
> +: (fdt-cas-delete-obsolete-aliases) ( xt -- )
> +    dup IF
> +	dup @
> +	recurse
> +	dup alias-name s" name" str= IF ELSE
> +	    dup fdt-cas-alias-obsolete? IF
> +		fdt-debug IF ." Deleting obsolete alias: " dup alias-name type ."  -> " dup alias-dev-path type cr THEN
> +		dup alias-name
> +		delete-property
> +	    THEN
> +	THEN
> +    THEN
> +    drop
> +;
> +
> +: fdt-cas-delete-obsolete-aliases ( -- )
> +    s" /aliases" find-device
> +    get-node node>properties @ cell+ @ (fdt-cas-delete-obsolete-aliases)
> +    device-end
> +;
> +
> +: fdt-cas-node-obsolete? ( node -- true|false)
> +    s" slof,from-fdt" rot get-package-property IF
> +	\ Not a QEMU originated node
> +	false
> +    ELSE
> +	decode-int nip nip fdt-generation# <
> +    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
> +    THEN
> +    2drop
> +;
> +
> +: fdt-cas-delete-obsolete-nodes ( start -- )
> +    s" /" find-device get-node (fdt-cas-search-obsolete-nodes)
> +    fdt-cas-delete-obsolete-aliases
> +;
> +
>  : 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
>      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
> 

-- 
Alexey