chelsio/chtls: Use splice_eof() to flush

Allow splice to end a Chelsio TLS record after prematurely ending a
splice/sendfile due to getting an EOF condition (->splice_read() returned
0) after splice had called sendmsg() with MSG_MORE set when the user didn't
set MSG_MORE.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/CAHk-=wh=V579PDYvkpnTobCLGczbgxpMgGmmhqiTyE34Cpi5Gg@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Ayush Sawal <ayush.sawal@chelsio.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls.h

@@ -568,6 +568,7 @@ void chtls_destroy_sock(struct sock *sk);
 int chtls_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
 int chtls_recvmsg(struct sock *sk, struct msghdr *msg,
 		  size_t len, int flags, int *addr_len);
+void chtls_splice_eof(struct socket *sock);
 int chtls_sendpage(struct sock *sk, struct page *page,
 		   int offset, size_t size, int flags);
 int send_tx_flowc_wr(struct sock *sk, int compl,

drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c

@@ -1237,6 +1237,15 @@ int chtls_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	goto done;
 }
 
+void chtls_splice_eof(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+
+	lock_sock(sk);
+	chtls_tcp_push(sk, 0);
+	release_sock(sk);
+}
+
 int chtls_sendpage(struct sock *sk, struct page *page,
 		   int offset, size_t size, int flags)
 {

drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_main.c

@@ -606,6 +606,7 @@ static void __init chtls_init_ulp_ops(void)
 	chtls_cpl_prot.destroy		= chtls_destroy_sock;
 	chtls_cpl_prot.shutdown		= chtls_shutdown;
 	chtls_cpl_prot.sendmsg		= chtls_sendmsg;
+	chtls_cpl_prot.splice_eof	= chtls_splice_eof;
 	chtls_cpl_prot.sendpage		= chtls_sendpage;
 	chtls_cpl_prot.recvmsg		= chtls_recvmsg;
 	chtls_cpl_prot.setsockopt	= chtls_setsockopt;