From nobody Tue Feb 10 19:00:45 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32FEAC761AF for ; Wed, 29 Mar 2023 14:17:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229552AbjC2ORj (ORCPT ); Wed, 29 Mar 2023 10:17:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53570 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230451AbjC2OQo (ORCPT ); Wed, 29 Mar 2023 10:16:44 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA9014C3E for ; Wed, 29 Mar 2023 07:15:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680099254; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Jo7xD6cW+5TTIp8oqR2hYvnkWHwWe/N8CbruF8cE9GA=; b=XSorInbJHYv7h0BCJsb/2BlcJsTxSyyglGtCgq/izDeFljKyhqfM0I8+mZxo/kg4Y6YZgR YP7gqXE8Ghnsea46ocW0FpYKxg/MWCGwZPuhsQgP3Z3MZpzNo5P8R16sR+5r13ZxxUsUnq DqFqOEzAQdBHRBR7zJaY8dmQ7pl4khw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-228-hXJAadh0MrOcoI5-BRrEXg-1; Wed, 29 Mar 2023 10:14:11 -0400 X-MC-Unique: hXJAadh0MrOcoI5-BRrEXg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 42E2B185A78B; Wed, 29 Mar 2023 14:14:10 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4BD8D2166B33; Wed, 29 Mar 2023 14:14:08 +0000 (UTC) From: David Howells To: Matthew Wilcox , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: David Howells , Al Viro , Christoph Hellwig , Jens Axboe , Jeff Layton , Christian Brauner , Chuck Lever III , Linus Torvalds , netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Willem de Bruijn Subject: [RFC PATCH v2 04/48] net: Declare MSG_SPLICE_PAGES internal sendmsg() flag Date: Wed, 29 Mar 2023 15:13:10 +0100 Message-Id: <20230329141354.516864-5-dhowells@redhat.com> In-Reply-To: <20230329141354.516864-1-dhowells@redhat.com> References: <20230329141354.516864-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Declare MSG_SPLICE_PAGES, an internal sendmsg() flag, that hints to a network protocol that it should splice pages from the source iterator rather than copying the data if it can. This flag is added to a list that is cleared by sendmsg and recvmsg syscalls on entry. This is intended as a replacement for the ->sendpage() op, allowing a way to splice in several multipage folios in one go. Signed-off-by: David Howells cc: Willem de Bruijn cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- include/linux/socket.h | 3 +++ net/socket.c | 7 +++++++ 2 files changed, 10 insertions(+) diff --git a/include/linux/socket.h b/include/linux/socket.h index 13c3a237b9c9..c2fa0f800999 100644 --- a/include/linux/socket.h +++ b/include/linux/socket.h @@ -327,6 +327,7 @@ struct ucred { */ =20 #define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */ +#define MSG_SPLICE_PAGES 0x8000000 /* Splice the pages from the iterator i= n sendmsg() */ #define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */ #define MSG_CMSG_CLOEXEC 0x40000000 /* Set close_on_exec for file descriptor received through @@ -337,6 +338,8 @@ struct ucred { #define MSG_CMSG_COMPAT 0 /* We never have 32 bit fixups */ #endif =20 +/* Flags to be cleared on entry by sendmsg, recvmsg, sendmmsg and recvmmsg= syscalls */ +#define MSG_INTERNAL_FLAGS (MSG_SPLICE_PAGES) =20 /* Setsockoptions(2) level. Thanks to BSD these must match IPPROTO_xxx */ #define SOL_IP 0 diff --git a/net/socket.c b/net/socket.c index 6bae8ce7059e..dfb912bbed62 100644 --- a/net/socket.c +++ b/net/socket.c @@ -2139,6 +2139,7 @@ int __sys_sendto(int fd, void __user *buff, size_t le= n, unsigned int flags, msg.msg_name =3D (struct sockaddr *)&address; msg.msg_namelen =3D addr_len; } + flags &=3D ~MSG_INTERNAL_FLAGS; if (sock->file->f_flags & O_NONBLOCK) flags |=3D MSG_DONTWAIT; msg.msg_flags =3D flags; @@ -2192,6 +2193,7 @@ int __sys_recvfrom(int fd, void __user *ubuf, size_t = size, unsigned int flags, if (!sock) goto out; =20 + flags &=3D ~MSG_INTERNAL_FLAGS; if (sock->file->f_flags & O_NONBLOCK) flags |=3D MSG_DONTWAIT; err =3D sock_recvmsg(sock, &msg, flags); @@ -2579,6 +2581,7 @@ long __sys_sendmsg(int fd, struct user_msghdr __user = *msg, unsigned int flags, =20 if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT)) return -EINVAL; + flags &=3D ~MSG_INTERNAL_FLAGS; =20 sock =3D sockfd_lookup_light(fd, &err, &fput_needed); if (!sock) @@ -2627,6 +2630,7 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mms= g, unsigned int vlen, entry =3D mmsg; compat_entry =3D (struct compat_mmsghdr __user *)mmsg; err =3D 0; + flags &=3D ~MSG_INTERNAL_FLAGS; flags |=3D MSG_BATCH; =20 while (datagrams < vlen) { @@ -2775,6 +2779,7 @@ long __sys_recvmsg_sock(struct socket *sock, struct m= sghdr *msg, struct user_msghdr __user *umsg, struct sockaddr __user *uaddr, unsigned int flags) { + flags &=3D ~MSG_INTERNAL_FLAGS; return ____sys_recvmsg(sock, msg, umsg, uaddr, flags, 0); } =20 @@ -2787,6 +2792,7 @@ long __sys_recvmsg(int fd, struct user_msghdr __user = *msg, unsigned int flags, =20 if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT)) return -EINVAL; + flags &=3D ~MSG_INTERNAL_FLAGS; =20 sock =3D sockfd_lookup_light(fd, &err, &fput_needed); if (!sock) @@ -2839,6 +2845,7 @@ static int do_recvmmsg(int fd, struct mmsghdr __user = *mmsg, goto out_put; } } + flags &=3D ~MSG_INTERNAL_FLAGS; =20 entry =3D mmsg; compat_entry =3D (struct compat_mmsghdr __user *)mmsg;