From: Laszlo Ersek <lersek@redhat.com>
Sent: Sunday, February 25, 2024 7:59 AM
To: Hsueh, Hong-Chih (Neo) <Hong-Chih.Hsueh@amd.com>; devel@edk2.groups.io <devel@edk2.groups.io>
Cc: Ding, Feng (Sunnyvale) <feng1.ding@amd.com>; He, Jiangang <Jiangang.He@amd.com>; Chang, Abner <Abner.Chang@amd.com>; ray.ni@intel.com <ray.ni@intel.com>; gaoliming@byosoft.com.cn <gaoliming@byosoft.com.cn>
Subject: Re: [PATCH v2] MdeModulePkg/PciBusDxe: plug device hierarchy leak upon bridge hot-unplug

Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.


On 2/22/24 17:28, Neo Hsueh wrote:
> A USB4 or TBT bridge can be plugged or unplugged on USB4 port. The actions require PciHotPlugRequestNotify to add a root bridge or remove a root bridge completely.
> In the plug-unplug-plug scenerio, PciHotPlugRequestNotify will return with no-action on second plug because bridge tree shows configured.
> Destroy Pci Device Tree in function PciHotPlugRequestNotify for unplug event to fix this issue.
>
> Cc: Feng Ding <feng1.ding@amd.com>
> Cc: Jiangang He <jiangang.he@amd.com>
> Signed-off-by: Neo Hsueh <Hong-Chih.Hsueh@amd.com>
> ---
>  MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumerator.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumerator.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumerator.c
> index 3f8c6e6da7..2b7af60e0a 100644
> --- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumerator.c
> +++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumerator.c
> @@ -2103,6 +2103,8 @@ PciHotPlugRequestNotify (
>        }
>      }
>
> +    DestroyPciDeviceTree (Bridge);
> +
>      //
>      // End for
>      //

This looks convincing to me, but I don't now nearly enough about
PciBusDxe internals (resource management in particular) to confidently
approve this patch. I can give an

Acked-by: Laszlo Ersek <lersek@redhat.com>

but the patch should not be merged until Ray provides an R-b.

Laszlo