Re: [EXT] Re: Ping frame drop

Please don't top post.

On Sat, 19 Jun 2021 15:14:35 +0000 Arijit De wrote:

In my network card HW it can verify the received frame's checksum of
IPv4 header, but it can't verify the checksum of ICMP header. 

Linux does not offload IPv4 header checksums.

So for
ICMP kind of received frames driver sets the checksum state to
CHECKSUM_PARTIAL in skb->ip_summed. Which is as per the linux kernel
documentation also. 

What documentation are you reading? Setting ip_summed to PARTIAL on
receive is only valid for software/virtual devices, never real HW.

Now before the commit
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8f9a69a92fc63917c9bd921b28e3b2912980becf
this use case was working. But now after introducing this logic for
CHECKSUM_PARTIAL case, my received ICMP ping frames are getting
dropped in the linux kernel pskb_trim_rcsum_slow(). I do understand
that to bypass this scenario I can use CHECKSUM_NONE, but in that
case HW's capability where checksum is already verified for the IPv4
header will be unutilized. 

So please do share if any documentation update has happened for the
CHECKSUM_PARTIAL scenario or please do let me know what need to be
updated in the skb for the receive frame in this scenario where only
Networking layer (i.e. IPv4 in this case) checksum is verified but
the ICMP(ping) header checksum is not verified  ?