This is a note to let you know that I've just added the patch titled net: dsa: hellcreek: Calculate checksums in tagger to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-dsa-hellcreek-calculate-checksums-in-tagger.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 10baf446d2207839ebfb7bd3bd7e21274192ec70 Author: Kurt Kanzenbach <kurt@xxxxxxxxxxxxx> Date: Fri Apr 15 12:33:20 2022 +0200 net: dsa: hellcreek: Calculate checksums in tagger [ Upstream commit 0763120b090418a5257402754e22a34227ae5f12 ] In case the checksum calculation is offloaded to the DSA master network interface, it will include the switch trailing tag. As soon as the switch strips that tag on egress, the calculated checksum is wrong. Therefore, add the checksum calculation to the tagger (if required) before adding the switch tag. This way, the hellcreek code works with all DSA master interfaces regardless of their declared feature set. Fixes: 01ef09caad66 ("net: dsa: Add tag handling for Hirschmann Hellcreek switches") Signed-off-by: Kurt Kanzenbach <kurt@xxxxxxxxxxxxx> Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx> Link: https://lore.kernel.org/r/20220415103320.90657-1-kurt@xxxxxxxxxxxxx Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/dsa/tag_hellcreek.c b/net/dsa/tag_hellcreek.c index f64b805303cd..eb204ad36eee 100644 --- a/net/dsa/tag_hellcreek.c +++ b/net/dsa/tag_hellcreek.c @@ -21,6 +21,14 @@ static struct sk_buff *hellcreek_xmit(struct sk_buff *skb, struct dsa_port *dp = dsa_slave_to_port(dev); u8 *tag; + /* Calculate checksums (if required) before adding the trailer tag to + * avoid including it in calculations. That would lead to wrong + * checksums after the switch strips the tag. + */ + if (skb->ip_summed == CHECKSUM_PARTIAL && + skb_checksum_help(skb)) + return NULL; + /* Tag encoding */ tag = skb_put(skb, HELLCREEK_TAG_LEN); *tag = BIT(dp->index);