bpf: Improve socket lookup reuseport documentation

Improve the wording around socket lookup for reuseport sockets, and
ensure that both bpf.h headers are in sync.

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/uapi/linux/bpf.h

@@ -2203,6 +2203,8 @@ union bpf_attr {
  *		**CONFIG_NET** configuration option.
  *	Return
  *		Pointer to *struct bpf_sock*, or NULL in case of failure.
+ *		For sockets with reuseport option, the *struct bpf_sock*
+ *		result is from reuse->socks[] using the hash of the tuple.
  *
  * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
  *	Description
@@ -2237,6 +2239,8 @@ union bpf_attr {
  *		**CONFIG_NET** configuration option.
  *	Return
  *		Pointer to *struct bpf_sock*, or NULL in case of failure.
+ *		For sockets with reuseport option, the *struct bpf_sock*
+ *		result is from reuse->socks[] using the hash of the tuple.
  *
  * int bpf_sk_release(struct bpf_sock *sk)
  *	Description

tools/include/uapi/linux/bpf.h

@@ -2203,8 +2203,8 @@ union bpf_attr {
  *		**CONFIG_NET** configuration option.
  *	Return
  *		Pointer to *struct bpf_sock*, or NULL in case of failure.
- *		For sockets with reuseport option, *struct bpf_sock*
- *		return is from reuse->socks[] using hash of the packet.
+ *		For sockets with reuseport option, the *struct bpf_sock*
+ *		result is from reuse->socks[] using the hash of the tuple.
  *
  * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
  *	Description
@@ -2239,8 +2239,8 @@ union bpf_attr {
  *		**CONFIG_NET** configuration option.
  *	Return
  *		Pointer to *struct bpf_sock*, or NULL in case of failure.
- *		For sockets with reuseport option, *struct bpf_sock*
- *		return is from reuse->socks[] using hash of the packet.
+ *		For sockets with reuseport option, the *struct bpf_sock*
+ *		result is from reuse->socks[] using the hash of the tuple.
  *
  * int bpf_sk_release(struct bpf_sock *sk)
  *	Description