Re: [edk2-devel] [PATCH] MdeModulePkg/SMM: Support to unregister SMI handler inside SMI handler

["Ni, Ray" <ray.ni@intel.com>]

Felix, I remember you mentioned to me about the usage of SMI handler unregistering itself.

Reviewed-by: Ray Ni <ray.ni@intel.com>

Thanks,
Ray
> -----Original Message-----
> From: Liu, Zhiguang <zhiguang.liu@intel.com>
> Sent: Wednesday, January 24, 2024 12:03 PM
> To: devel@edk2.groups.io
> Cc: Liu, Zhiguang <zhiguang.liu@intel.com>; Liming Gao
> <gaoliming@byosoft.com.cn>; Wu, Jiaxin <jiaxin.wu@intel.com>; Ni, Ray
> <ray.ni@intel.com>
> Subject: [PATCH] MdeModulePkg/SMM: Support to unregister SMI handler
> inside SMI handler
> 
> To support unregister SMI handler inside SMI handler itself,
> get next node before SMI handler is executed, since LIST_ENTRY that
> Link points to may be freed if unregister SMI handler in SMI handler
> itself.
> 
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Jiaxin Wu <jiaxin.wu@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>
> ---
>  MdeModulePkg/Core/PiSmmCore/Smi.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/MdeModulePkg/Core/PiSmmCore/Smi.c
> b/MdeModulePkg/Core/PiSmmCore/Smi.c
> index 2985f989c3..a75e52b1ae 100644
> --- a/MdeModulePkg/Core/PiSmmCore/Smi.c
> +++ b/MdeModulePkg/Core/PiSmmCore/Smi.c
> @@ -134,8 +134,14 @@ SmiManage (
> 
>    Head = &SmiEntry->SmiHandlers;
> 
> -  for (Link = Head->ForwardLink; Link != Head; Link = Link->ForwardLink) {
> +  for (Link = Head->ForwardLink; Link != Head;) {
>      SmiHandler = CR (Link, SMI_HANDLER, Link,
> SMI_HANDLER_SIGNATURE);
> +    //
> +    // To support unregiser SMI handler inside SMI handler itself,
> +    // get next node before handler is executed, since LIST_ENTRY that
> +    // Link points to may be freed if unregister SMI handler.
> +    //
> +    Link = Link->ForwardLink;
> 
>      Status = SmiHandler->Handler (
>                             (EFI_HANDLE)SmiHandler,
> --
> 2.31.1.windows.1



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