Some sockets don't care about msghdr::ubuf_info and would execute the request by copying data. Such fallback behaviour was always a pain in my experience, so we'd rather want to fail such requests and have a more robust api in the future. Mark struct socket that support it with a new SOCK_SUPPORT_ZC flag. I'm not entirely sure it's the best place for the flag but at least we don't have to do a bunch of extra dereferences in the hot path. P.S. patches 2 and 3 are not combined for backporting purposes. Pavel Begunkov (3): net: flag sockets supporting msghdr originated zerocopy io_uring/net: fail zc send when unsupported by socket io_uring/net: fail zc sendmsg when unsupported by socket include/linux/net.h | 1 + io_uring/net.c | 4 ++++ net/ipv4/tcp.c | 1 + net/ipv4/udp.c | 1 + 4 files changed, 7 insertions(+) -- 2.38.0
