Re: [PATCH bpf 1/3] bpf, sockmap: zap ingress queues after stopping strparser
From: Jakub Sitnicki <jakub@cloudflare.com>
Date: 2021-07-20 10:31:37
Also in:
bpf
On Mon, Jul 19, 2021 at 11:48 PM CEST, John Fastabend wrote:
We don't want strparser to run and pass skbs into skmsg handlers when
the psock is null. We just sk_drop them in this case. When removing
a live socket from map it means extra drops that we do not need to
incur. Move the zap below strparser close to avoid this condition.
This way we stop the stream parser first stopping it from processing
packets and then delete the psock.
Fixes: a136678c0bdbb ("bpf: sk_msg, zap ingress queue on psock down")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
---To confirm my understanding - the extra drops can happen because currently we are racing to clear SK_PSOCK_TX_ENABLED flag in sk_psock_drop with sk_psock_verdict_apply, which checks the flag before pushing skb onto psock->ingress_skb queue (or possibly straight into psock->ingress_msg queue on no redirect).