netdev - [RFC PATCH 05/28] tcp_bpf: Inline do_tcp_sendpages as it's now a wrapper around tcp

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Message-Id: <20230316152618.711970-6-dhowells@redhat.com>
Date:   Thu, 16 Mar 2023 15:25:55 +0000
From:   David Howells <dhowells@...hat.com>
To:     Matthew Wilcox <willy@...radead.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     David Howells <dhowells@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@...radead.org>,
        Jens Axboe <axboe@...nel.dk>, Jeff Layton <jlayton@...nel.org>,
        Christian Brauner <brauner@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        netdev@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        John Fastabend <john.fastabend@...il.com>,
        Jakub Sitnicki <jakub@...udflare.com>, bpf@...r.kernel.org
Subject: [RFC PATCH 05/28] tcp_bpf: Inline do_tcp_sendpages as it's now a wrapper around tcp_sendmsg

do_tcp_sendpages() is now just a small wrapper around tcp_sendmsg_locked(),
so inline it.  This is part of replacing ->sendpage() with a call to
sendmsg() with MSG_SPLICE_PAGES set.

Signed-off-by: David Howells <dhowells@...hat.com>
cc: John Fastabend <john.fastabend@...il.com>
cc: Jakub Sitnicki <jakub@...udflare.com>
cc: "David S. Miller" <davem@...emloft.net>
cc: Eric Dumazet <edumazet@...gle.com>
cc: Jakub Kicinski <kuba@...nel.org>
cc: Paolo Abeni <pabeni@...hat.com>
cc: Jens Axboe <axboe@...nel.dk>
cc: Matthew Wilcox <willy@...radead.org>
cc: netdev@...r.kernel.org
cc: bpf@...r.kernel.org
---
 net/ipv4/tcp_bpf.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index cf26d65ca389..7f17134637eb 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -72,11 +72,13 @@ static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
 {
 	bool apply = apply_bytes;
 	struct scatterlist *sge;
+	struct msghdr msghdr = { .msg_flags = flags | MSG_SPLICE_PAGES, };
 	struct page *page;
 	int size, ret = 0;
 	u32 off;
 
 	while (1) {
+		struct bio_vec bvec;
 		bool has_tx_ulp;
 
 		sge = sk_msg_elem(msg, msg->sg.start);
@@ -88,16 +90,18 @@ static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
 		tcp_rate_check_app_limited(sk);
 retry:
 		has_tx_ulp = tls_sw_has_ctx_tx(sk);
-		if (has_tx_ulp) {
-			flags |= MSG_SENDPAGE_NOPOLICY;
-			ret = kernel_sendpage_locked(sk,
-						     page, off, size, flags);
-		} else {
-			ret = do_tcp_sendpages(sk, page, off, size, flags);
-		}
+		if (has_tx_ulp)
+			msghdr.msg_flags |= MSG_SENDPAGE_NOPOLICY;
 
+		if (flags & MSG_SENDPAGE_NOTLAST)
+			msghdr.msg_flags |= MSG_MORE;
+
+		bvec_set_page(&bvec, page, size, off);
+		iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, size);
+		ret = tcp_sendmsg_locked(sk, &msghdr, size);
 		if (ret <= 0)
 			return ret;
+
 		if (apply)
 			apply_bytes -= ret;
 		msg->sg.size -= ret;
@@ -398,7 +402,7 @@ static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	long timeo;
 	int flags;
 
-	/* Don't let internal do_tcp_sendpages() flags through */
+	/* Don't let internal sendpage flags through */
 	flags = (msg->msg_flags & ~MSG_SENDPAGE_DECRYPTED);
 	flags |= MSG_NO_SHARED_FRAGS;