From: Daniel Borkmann <daniel@iogearbox.net>
Date: Sat, 20 Jan 2018 01:24:37 +0100
Subject: bpf: move event_output to const_size_or_zero for xdp/skb as well
Patch-mainline: v4.16-rc1
Git-commit: 1728a4f2ad6840746a6b1b9f01d652c5842f7e8d
References: bsc#1109837

Similar rationale as in a60dd35d2e39 ("bpf: change bpf_perf_event_output
arg5 type to ARG_CONST_SIZE_OR_ZERO"), change the type to CONST_SIZE_OR_ZERO
such that we can better deal with optimized code. No changes needed in
bpf_event_output() as it can also deal with 0 size entirely (e.g. as only
wake-up signal with empty frame in perf RB, or packet dumps w/o meta data
as another such possibility).

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/core/filter.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2864,7 +2864,7 @@ static const struct bpf_func_proto bpf_s
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
 	.arg4_type	= ARG_PTR_TO_MEM,
-	.arg5_type	= ARG_CONST_SIZE,
+	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
 static unsigned short bpf_tunnel_key_af(u64 flags)
@@ -3153,7 +3153,7 @@ static const struct bpf_func_proto bpf_x
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
 	.arg4_type	= ARG_PTR_TO_MEM,
-	.arg5_type	= ARG_CONST_SIZE,
+	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
 BPF_CALL_1(bpf_get_socket_cookie, struct sk_buff *, skb)