netdev - [RFC PATCH bpf-next 3/9] xsk: add support for recvmsg()

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Message-Id: <20201028133437.212503-4-bjorn.topel@gmail.com>
Date:   Wed, 28 Oct 2020 14:34:31 +0100
From:   Björn Töpel <bjorn.topel@...il.com>
To:     netdev@...r.kernel.org, bpf@...r.kernel.org
Cc:     Björn Töpel <bjorn.topel@...el.com>,
        magnus.karlsson@...el.com, ast@...nel.org, daniel@...earbox.net,
        maciej.fijalkowski@...el.com, sridhar.samudrala@...el.com,
        jesse.brandeburg@...el.com, qi.z.zhang@...el.com, kuba@...nel.org,
        edumazet@...gle.com, intel-wired-lan@...ts.osuosl.org,
        jonathan.lemon@...il.com
Subject: [RFC PATCH bpf-next 3/9] xsk: add support for recvmsg()

From: Björn Töpel <bjorn.topel@...el.com>

Add support for non-blocking recvmsg() to XDP sockets. Previously,
only sendmsg() was supported by XDP socket. Now, for symmetry and the
upcoming busy-polling support, recvmsg() is added.

Signed-off-by: Björn Töpel <bjorn.topel@...el.com>
---
 net/xdp/xsk.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index b71a32eeae65..17d51d1a5752 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -474,6 +474,26 @@ static int xsk_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
 	return __xsk_sendmsg(sk);
 }
 
+static int xsk_recvmsg(struct socket *sock, struct msghdr *m, size_t len, int flags)
+{
+	bool need_wait = !(flags & MSG_DONTWAIT);
+	struct sock *sk = sock->sk;
+	struct xdp_sock *xs = xdp_sk(sk);
+
+	if (unlikely(!(xs->dev->flags & IFF_UP)))
+		return -ENETDOWN;
+	if (unlikely(!xs->rx))
+		return -ENOBUFS;
+	if (unlikely(!xsk_is_bound(xs)))
+		return -ENXIO;
+	if (unlikely(need_wait))
+		return -EOPNOTSUPP;
+
+	if (xs->pool->cached_need_wakeup & XDP_WAKEUP_RX && xs->zc)
+		return xsk_wakeup(xs, XDP_WAKEUP_RX);
+	return 0;
+}
+
 static __poll_t xsk_poll(struct file *file, struct socket *sock,
 			     struct poll_table_struct *wait)
 {
@@ -1134,7 +1154,7 @@ static const struct proto_ops xsk_proto_ops = {
 	.setsockopt	= xsk_setsockopt,
 	.getsockopt	= xsk_getsockopt,
 	.sendmsg	= xsk_sendmsg,
-	.recvmsg	= sock_no_recvmsg,
+	.recvmsg	= xsk_recvmsg,
 	.mmap		= xsk_mmap,
 	.sendpage	= sock_no_sendpage,
 };
-- 
2.27.0