Re: [Patch] MdeModulePkg/Mtftp4Dxe: Restore the TPL before the poll function.

["Fu, Siyuan" <siyuan.fu@intel.com>]

Hi, Jiaxin

Do you mean the code which calls MTFTP4->Poll() at TPL_CALLBACK will cause system hang? This should not happen because all network protocol should be able to run at TPL_CALLBACK.

BestRegards
Fu Siyuan


> -----Original Message-----
> From: Wu, Jiaxin
> Sent: Thursday, March 1, 2018 5:38 PM
> To: edk2-devel@lists.01.org
> Cc: Wang, Fan <fan.wang@intel.com>; Fu, Siyuan <siyuan.fu@intel.com>; Ye,
> Ting <ting.ye@intel.com>
> Subject: [Patch] MdeModulePkg/Mtftp4Dxe: Restore the TPL before the poll
> function.
> 
> This patch is to fix the hang issue, which was enrolled by the commit of
> 39b0867d.
> The TPL should be restored before calling poll function at TPL_CALLBACK.
> 
> Cc: Wang Fan <fan.wang@intel.com>
> Cc: Fu Siyuan <siyuan.fu@intel.com>
> Cc: Ye Ting <ting.ye@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
> ---
>  MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.c
> b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.c
> index f5f9e6d8f7..64e0463dd9 100644
> --- a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.c
> +++ b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.c
> @@ -507,24 +507,27 @@ Mtftp4Start (
>    if (EFI_ERROR (Status)) {
>      Status = EFI_DEVICE_ERROR;
>      goto ON_ERROR;
>    }
> 
> +  //
> +  // Restore the TPL now, don't call poll function at TPL_CALLBACK.
> +  //
> +  gBS->RestoreTPL (OldTpl);
> +
>    if (Token->Event != NULL) {
> -    gBS->RestoreTPL (OldTpl);
>      return EFI_SUCCESS;
>    }
> 
>    //
>    // Return immediately for asynchronous operation or poll the
>    // instance for synchronous operation.
>    //
>    while (Token->Status == EFI_NOT_READY) {
>      This->Poll (This);
>    }
> -
> -  gBS->RestoreTPL (OldTpl);
> +
>    return Token->Status;
> 
>  ON_ERROR:
>    Mtftp4CleanOperation (Instance, Status);
>    gBS->RestoreTPL (OldTpl);
> --
> 2.16.2.windows.1