Device memory send doesn't work without zero copy, prevent tcp_sendmsg_locked() from falling back to the copy mode for devmem in case there is no NETIF_F_SG. Currently, it'd try to copy from iovec filled with dma-buf offsets, which would normally fail with EFAULT, but it's still better to handle it more explicitly. A recent net-iov / page mixing fix also needs this patch. Fixes: bd61848900bff ("net: devmem: Implement TX path") Signed-off-by: Pavel Begunkov --- net/ipv4/tcp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 455441f1b694..f403830af65f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1162,6 +1162,10 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) binding = NULL; goto out_err; } + if (zc != MSG_ZEROCOPY) { + err = -EOPNOTSUPP; + goto out_err; + } } } } else if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES) && size) { -- 2.54.0