Subject: [PATCH net-next v3 03/18] tcp_bpf, smc, tls, espintcp: Reduce MSG_SENDPAGE_NOTLAST usage

From: David Howells <[email-masked]>
Date: Tue, 20 Jun 2023 15:53:22 +0100

As MSG_SENDPAGE_NOTLAST is being phased out along with sendpage(), don't
use it further in than the sendpage methods, but rather translate it to
MSG_MORE and use that instead.

Signed-off-by: David Howells <[email-masked]>
cc: Willem de Bruijn <[email-masked]>
cc: John Fastabend <[email-masked]>
cc: Jakub Sitnicki <[email-masked]>
cc: Eric Dumazet <[email-masked]>
cc: "David S. Miller" <[email-masked]>
cc: David Ahern <[email-masked]>
cc: Jakub Kicinski <[email-masked]>
cc: Paolo Abeni <[email-masked]>
cc: Karsten Graul <[email-masked]>
cc: Wenjia Zhang <[email-masked]>
cc: Jan Karcher <[email-masked]>
cc: "D. Wythe" <[email-masked]>
cc: Tony Lu <[email-masked]>
cc: Wen Gu <[email-masked]>
cc: Boris Pismenny <[email-masked]>
cc: Steffen Klassert <[email-masked]>
cc: Herbert Xu <[email-masked]>
cc: [email-masked]
cc: [email-masked]
cc: [email-masked]
---

Notes:
    ver #3)
     - In tcp_bpf, reset msg_flags on each iteration to clear MSG_MORE.
     - In tcp_bpf, set MSG_MORE if there's more data in the sk_msg.

 net/ipv4/tcp_bpf.c   |  5 +++--
 net/smc/smc_tx.c     |  6 ++++--
 net/tls/tls_device.c |  4 ++--
 net/xfrm/espintcp.c  | 10 ++++++----
 4 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 5a84053ac62b..31d6005cea9b 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -88,9 +88,9 @@ static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
 static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
 			int flags, bool uncharge)
 {
+	struct msghdr msghdr = {};
 	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;
@@ -107,11 +107,12 @@ static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
 
 		tcp_rate_check_app_limited(sk);
 retry:
+		msghdr.msg_flags = flags | MSG_SPLICE_PAGES;
 		has_tx_ulp = tls_sw_has_ctx_tx(sk);
 		if (has_tx_ulp)
 			msghdr.msg_flags |= MSG_SENDPAGE_NOPOLICY;
 
-		if (flags & MSG_SENDPAGE_NOTLAST)
+		if (size < sge->length && msg->sg.start != msg->sg.end)
 			msghdr.msg_flags |= MSG_MORE;
 
 		bvec_set_page(&bvec, page, size, off);
diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
index 45128443f1f1..9b9e0a190734 100644
--- a/net/smc/smc_tx.c
+++ b/net/smc/smc_tx.c
@@ -168,8 +168,7 @@ static bool smc_tx_should_cork(struct smc_sock *smc, struct msghdr *msg)
 	 * should known how/when to uncork it.
 	 */
 	if ((msg->msg_flags & MSG_MORE ||
-	     smc_tx_is_corked(smc) ||
-	     msg->msg_flags & MSG_SENDPAGE_NOTLAST) &&
+	     smc_tx_is_corked(smc)) &&
 	    atomic_read(&conn->sndbuf_space))
 		return true;
 
@@ -306,6 +305,9 @@ int smc_tx_sendpage(struct smc_sock *smc, struct page *page, int offset,
 	struct kvec iov;
 	int rc;
 
+	if (flags & MSG_SENDPAGE_NOTLAST)
+		msg.msg_flags |= MSG_MORE;
+
 	iov.iov_base = kaddr + offset;
 	iov.iov_len = size;
 	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &iov, 1, size);
diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index b82770f68807..975299d7213b 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -449,7 +449,7 @@ static int tls_push_data(struct sock *sk,
 		return -sk->sk_err;
 
 	flags |= MSG_SENDPAGE_DECRYPTED;
-	tls_push_record_flags = flags | MSG_SENDPAGE_NOTLAST;
+	tls_push_record_flags = flags | MSG_MORE;
 
 	timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 	if (tls_is_partially_sent_record(tls_ctx)) {
@@ -532,7 +532,7 @@ static int tls_push_data(struct sock *sk,
 		if (!size) {
 last_record:
 			tls_push_record_flags = flags;
-			if (flags & (MSG_SENDPAGE_NOTLAST | MSG_MORE)) {
+			if (flags & MSG_MORE) {
 				more = true;
 				break;
 			}
diff --git a/net/xfrm/espintcp.c b/net/xfrm/espintcp.c
index 3504925babdb..d3b3f9e720b3 100644
--- a/net/xfrm/espintcp.c
+++ b/net/xfrm/espintcp.c
@@ -205,13 +205,15 @@ static int espintcp_sendskb_locked(struct sock *sk, struct espintcp_msg *emsg,
 static int espintcp_sendskmsg_locked(struct sock *sk,
 				     struct espintcp_msg *emsg, int flags)
 {
-	struct msghdr msghdr = { .msg_flags = flags | MSG_SPLICE_PAGES, };
+	struct msghdr msghdr = {
+		.msg_flags = flags | MSG_SPLICE_PAGES | MSG_MORE,
+	};
 	struct sk_msg *skmsg = &emsg->skmsg;
+	bool more = flags & MSG_MORE;
 	struct scatterlist *sg;
 	int done = 0;
 	int ret;
 
-	msghdr.msg_flags |= MSG_SENDPAGE_NOTLAST;
 	sg = &skmsg->sg.data[skmsg->sg.start];
 	do {
 		struct bio_vec bvec;
@@ -221,8 +223,8 @@ static int espintcp_sendskmsg_locked(struct sock *sk,
 
 		emsg->offset = 0;
 
-		if (sg_is_last(sg))
-			msghdr.msg_flags &= ~MSG_SENDPAGE_NOTLAST;
+		if (sg_is_last(sg) && !more)
+			msghdr.msg_flags &= ~MSG_MORE;
 
 		p = sg_page(sg);
 retry: