MdeModulePkg/UefiPxeBcDxe: Question about IcmpErrorListenHandler in PxeBcImpl.c

[Guo Heyi <heyi.guo@linaro.org>]

Hi folks,

In PxeBcImpl.c, we have IcmpErrorListenHandler which seems to process ICMP errors. But in EfiPxeBcStart function, we can see Private->IcmpErrorRcvToken.Event is only a common event and Ip4->Receive is called to receive IP4 packets. So will IcmpErrorListenHandler receive all IP4 packets belonging to this network interface, or will it only receive ICMP error packets? If it is the latter situation, how do we make it?

The background of this question is that when we flush the network with deprecated ICMP packets (type 15, 16, ...), RxData will not be recycled and the list of UEFI events becomes longer and longer, which finally impacts system performance a lot. If only error ICMP will be received by IcmpErrorListenHandler, we'd like to patch it as below:

diff --git a/MdeModulePkg/Universal/Network/UefiPxeBcDxe/PxeBcImpl.c b/MdeModulePkg/Universal/Network/UefiPxeBcDxe/PxeBcImpl.c
index 6d4f33f..f74b264 100644
--- a/MdeModulePkg/Universal/Network/UefiPxeBcDxe/PxeBcImpl.c
+++ b/MdeModulePkg/Universal/Network/UefiPxeBcDxe/PxeBcImpl.c
@@ -216,8 +216,6 @@ IcmpErrorListenHandlerDpc (
     CopiedPointer += CopiedLen;
   }

-  goto Resume;
-
 CleanUp:
   gBS->SignalEvent (RxData->RecycleSignal);

We tested and it worked, but we are still not sure whether it will impact other code in the network stack.

Please let me know your comments.

Thanks,

Gary (Heyi Guo)