From patchwork Mon Apr 18 16:49:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever III X-Patchwork-Id: 12816891 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 DD908C433EF for ; Mon, 18 Apr 2022 16:49:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346427AbiDRQwN (ORCPT ); Mon, 18 Apr 2022 12:52:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346425AbiDRQwM (ORCPT ); Mon, 18 Apr 2022 12:52:12 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C34E32EC7; Mon, 18 Apr 2022 09:49:32 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D5D07612DC; Mon, 18 Apr 2022 16:49:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5625C385A7; Mon, 18 Apr 2022 16:49:30 +0000 (UTC) Subject: [PATCH RFC 1/5] net: Add distinct sk_psock field From: Chuck Lever To: netdev@vger.kernel.org, linux-nfs@vger.kernel.org, linux-nvme@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: ak@tempesta-tech.com, borisp@nvidia.com, simo@redhat.com Date: Mon, 18 Apr 2022 12:49:29 -0400 Message-ID: <165030056960.5073.6664402939918720250.stgit@oracle-102.nfsv4.dev> In-Reply-To: <165030051838.5073.8699008789153780301.stgit@oracle-102.nfsv4.dev> References: <165030051838.5073.8699008789153780301.stgit@oracle-102.nfsv4.dev> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org The sk_psock facility populates the sk_user_data field with the address of an extra bit of metadata. User space sockets never populate the sk_user_data field, so this has worked out fine. However, kernel consumers such as the RPC client and server do populate the sk_user_data field. The sk_psock() function cannot tell that the content of sk_user_data does not point to psock metadata, so it will happily return a pointer to something else, cast to a struct sk_psock. Thus kernel consumers and psock currently cannot co-exist. We could educate sk_psock() to return NULL if sk_user_data does not point to a struct sk_psock. However, a more general solution that enables full co-existence psock and other uses of sk_user_data might be more interesting. Move the struct sk_psock address to its own pointer field so that the contents of the sk_user_data field is preserved. Signed-off-by: Chuck Lever Reviewed-by: Hannes Reinecke --- include/linux/skmsg.h | 2 +- include/net/sock.h | 4 +++- net/core/skmsg.c | 6 +++--- 3 files changed, 7 insertions(+), 5 deletions(-) diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h index c5a2d6f50f25..5ef3a07c5b6c 100644 --- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -277,7 +277,7 @@ static inline void sk_msg_sg_copy_clear(struct sk_msg *msg, u32 start) static inline struct sk_psock *sk_psock(const struct sock *sk) { - return rcu_dereference_sk_user_data(sk); + return rcu_dereference(sk->sk_psock); } static inline void sk_psock_set_state(struct sk_psock *psock, diff --git a/include/net/sock.h b/include/net/sock.h index c4b91fc19b9c..d2a513169527 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -327,7 +327,8 @@ struct sk_filter; * @sk_tskey: counter to disambiguate concurrent tstamp requests * @sk_zckey: counter to order MSG_ZEROCOPY notifications * @sk_socket: Identd and reporting IO signals - * @sk_user_data: RPC layer private data + * @sk_user_data: Upper layer private data + * @sk_psock: socket policy data (bpf) * @sk_frag: cached page frag * @sk_peek_off: current peek_offset value * @sk_send_head: front of stuff to transmit @@ -519,6 +520,7 @@ struct sock { struct socket *sk_socket; void *sk_user_data; + struct sk_psock __rcu *sk_psock; #ifdef CONFIG_SECURITY void *sk_security; #endif diff --git a/net/core/skmsg.c b/net/core/skmsg.c index cc381165ea08..2b3d01d92790 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -695,7 +695,7 @@ struct sk_psock *sk_psock_init(struct sock *sk, int node) write_lock_bh(&sk->sk_callback_lock); - if (sk->sk_user_data) { + if (sk->sk_psock) { psock = ERR_PTR(-EBUSY); goto out; } @@ -726,7 +726,7 @@ struct sk_psock *sk_psock_init(struct sock *sk, int node) sk_psock_set_state(psock, SK_PSOCK_TX_ENABLED); refcount_set(&psock->refcnt, 1); - rcu_assign_sk_user_data_nocopy(sk, psock); + rcu_assign_pointer(sk->sk_psock, psock); sock_hold(sk); out: @@ -825,7 +825,7 @@ void sk_psock_drop(struct sock *sk, struct sk_psock *psock) { write_lock_bh(&sk->sk_callback_lock); sk_psock_restore_proto(sk, psock); - rcu_assign_sk_user_data(sk, NULL); + rcu_assign_pointer(sk->sk_psock, NULL); if (psock->progs.stream_parser) sk_psock_stop_strp(sk, psock); else if (psock->progs.stream_verdict || psock->progs.skb_verdict)