• John Fastabend's avatar
    bpf: sockmap: write_space events need to be passed to TCP handler · 9b2e0388
    John Fastabend authored
    When sockmap code is using the stream parser it also handles the write
    space events in order to handle the case where (a) verdict redirects
    skb to another socket and (b) the sockmap then sends the skb but due
    to memory constraints (or other EAGAIN errors) needs to do a retry.
    
    But the initial code missed a third case where the
    skb_send_sock_locked() triggers an sk_wait_event(). A typically case
    would be when sndbuf size is exceeded. If this happens because we
    do not pass the write_space event to the lower layers we never wake
    up the event and it will wait for sndtimeo. Which as noted in ktls
    fix may be rather large and look like a hang to the user.
    
    To reproduce the best test is to reduce the sndbuf size and send
    1B data chunks to stress the memory handling. To fix this pass the
    event from the upper layer to the lower layer.
    Signed-off-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
    Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
    9b2e0388
sockmap.c 59.9 KB