program-type/BPF_PROG_TYPE_SOCK_OPS: add mention of BPF_WRITE_HDR_TCP_CURRENT_MSS - #290
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…_CURRENT_MSS The kernel will sometime trigger the BPF_SOCK_OPS_HDR_OPT_LEN_CB event with a fake, empty packet to guess the future packet's size. See here https://elixir.bootlin.com/linux/v7.1.3/source/net/ipv4/tcp_output.c#L521. When that's the case, it will add `BPF_WRITE_HDR_TCP_CURRENT_MSS` as the first arg to notify that no space will be actually reserved.
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The kernel will sometime trigger the
BPF_SOCK_OPS_HDR_OPT_LEN_CBevent with a fake, empty packet to guess the future packet's size. See here https://elixir.bootlin.com/linux/v7.1.3/source/net/ipv4/tcp_output.c#L521.When that's the case, it will add
BPF_WRITE_HDR_TCP_CURRENT_MSSas the first arg to notify that no space will be actually reserved.