Messages in this thread | | | Date | Sat, 07 Dec 2019 11:10:58 +0300 | From | Alexander Lobakin <> | Subject | Re: [PATCH net] net: dsa: fix flow dissection on Tx path |
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David Miller wrote 07.12.2019 07:19: > From: Alexander Lobakin <alobakin@dlink.ru> > Date: Thu, 5 Dec 2019 13:02:35 +0300 > >> Commit 43e665287f93 ("net-next: dsa: fix flow dissection") added an >> ability to override protocol and network offset during flow dissection >> for DSA-enabled devices (i.e. controllers shipped as switch CPU ports) >> in order to fix skb hashing for RPS on Rx path. >> >> However, skb_hash() and added part of code can be invoked not only on >> Rx, but also on Tx path if we have a multi-queued device and: >> - kernel is running on UP system or >> - XPS is not configured. >> >> The call stack in this two cases will be like: dev_queue_xmit() -> >> __dev_queue_xmit() -> netdev_core_pick_tx() -> netdev_pick_tx() -> >> skb_tx_hash() -> skb_get_hash(). >> >> The problem is that skbs queued for Tx have both network offset and >> correct protocol already set up even after inserting a CPU tag by DSA >> tagger, so calling tag_ops->flow_dissect() on this path actually only >> breaks flow dissection and hashing. >> >> This can be observed by adding debug prints just before and right >> after >> tag_ops->flow_dissect() call to the related block of code: > ... >> In order to fix that we can add the check 'proto == htons(ETH_P_XDSA)' >> to prevent code from calling tag_ops->flow_dissect() on Tx. >> I also decided to initialize 'offset' variable so tagger callbacks can >> now safely leave it untouched without provoking a chaos. >> >> Fixes: 43e665287f93 ("net-next: dsa: fix flow dissection") >> Signed-off-by: Alexander Lobakin <alobakin@dlink.ru> > > Applied and queued up for -stable.
David, Andrew, Florian, Rainer, Thank you!
Regards, ᚷ ᛖ ᚢ ᚦ ᚠ ᚱ
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