Re: [PATCH net v3 2/2] vsock/bpf: fix zero-length, MSG_OOB and MSG_ERRQUEUE reads in recvmsg

[sashiko-bot@kernel.org]

> From: Jerome Mohm <jrmmhm.kernel@eldare.de>
> 
> vsock_bpf_recvmsg() sends every read that cannot be served from the
> transport's own queue through sk_msg_recvmsg() and its wait loop. Three
> kinds of read do not fit that path:
> 
>  - len == 0: with data queued in the psock ingress queue (for example
>    after an SK_PASS verdict), sk_msg_recvmsg() copies nothing and
>    returns 0, and the wait reports data ready at once, so the loop spins
>    with lock_sock() held. The vsock delivery worker then blocks on the
>    same lock and all rx on the transport stops (hung-task).
>    tcp_bpf, udp_bpf and unix_bpf return 0 early, and
>    __vsock_connectible_recvmsg() handles len == 0 too.
> 
>  - MSG_ERRQUEUE: the read only reaches sock_recv_errqueue() when the
> [ ... ]
> sockmap_basic and the 240 AF_VSOCK cases of sockmap_redir).
> 
> Fixes: 634f1a7110b4 ("vsock: support sockmap")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jerome Mohm <jrmmhm.kernel@eldare.de>

Sashiko has reviewed this patch and found no issues.

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