From 27b31e68bc9fc25c519c7772fa23913687218d5f Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Mon, 29 Oct 2018 12:31:28 -0700 Subject: [PATCH] bpf: tcp_bpf_recvmsg should return EAGAIN when nonblocking and no data We return 0 in the case of a nonblocking socket that has no data available. However, this is incorrect and may confuse applications. After this patch we do the correct thing and return the error EAGAIN. Quoting return codes from recvmsg manpage, EAGAIN or EWOULDBLOCK The socket is marked nonblocking and the receive operation would block, or a receive timeout had been set and the timeout expired before data was received. Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: John Fastabend Acked-by: Song Liu Signed-off-by: Daniel Borkmann --- net/ipv4/tcp_bpf.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index b7918d4caa30..3b45fe530f91 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -145,6 +145,7 @@ msg_bytes_ready: ret = err; goto out; } + copied = -EAGAIN; } ret = copied; out: -- 2.30.2