Hi all I am missing a full understanding of what really is thread safe and what is not, when using AF_XDP. RX and TX operations look obvious as every xsk socket has its own RX and TX rings and so I can have multiple threads, as long as they don't try to use the same ring of the same socket concurrently, that's the only limitation (Am I correct yet?). So I can have for example 1:1 mapping of thread to xsk socket to avoid locking. However what about UMEM rings, i.e. Completion and Fill queue? About ring operations as __peek, __reserve ..., it is written (for ex. here: https://www.kernel.org/doc/html/latest/networking/af_xdp.html#rings), that they are not thread safe. So it seems that I should use mutex to access them. But I can see in: https://github.com/xdp-project/bpf-examples/blob/master/AF_XDP-forwarding/xsk_fwd.c#L526 That they are filled / drained without locking, how is it then? Does it make a difference if the socket is created by xsk_socket__create_shared or xsk_socket__create? What is the limitation that cannot be broken, as I described it for RX / TX? (if correctly) Best Regards Julius
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