From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E91EC43381 for ; Thu, 21 Mar 2019 13:19:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6DAAD20830 for ; Thu, 21 Mar 2019 13:19:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728336AbfCUNS2 (ORCPT ); Thu, 21 Mar 2019 09:18:28 -0400 Received: from mail-il-dmz.mellanox.com ([193.47.165.129]:42351 "EHLO mellanox.co.il" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728311AbfCUNS2 (ORCPT ); Thu, 21 Mar 2019 09:18:28 -0400 Received: from Internal Mail-Server by MTLPINE1 (envelope-from vladbu@mellanox.com) with ESMTPS (AES256-SHA encrypted); 21 Mar 2019 15:18:25 +0200 Received: from reg-r-vrt-018-180.mtr.labs.mlnx. (reg-r-vrt-018-180.mtr.labs.mlnx [10.213.18.180]) by labmailer.mlnx (8.13.8/8.13.8) with ESMTP id x2LDIPdK019148; Thu, 21 Mar 2019 15:18:25 +0200 From: Vlad Buslov To: netdev@vger.kernel.org Cc: jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net, sbrivio@redhat.com, Vlad Buslov Subject: [PATCH net-next v3 01/12] net: sched: flower: don't check for rtnl on head dereference Date: Thu, 21 Mar 2019 15:17:33 +0200 Message-Id: <20190321131744.19224-2-vladbu@mellanox.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190321131744.19224-1-vladbu@mellanox.com> References: <20190321131744.19224-1-vladbu@mellanox.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Flower classifier only changes root pointer during init and destroy. Cls API implements reference counting for tcf_proto, so there is no danger of concurrent access to tp when it is being destroyed, even without protection provided by rtnl lock. Implement new function fl_head_dereference() to dereference tp->root without checking for rtnl lock. Use it in all flower function that obtain head pointer instead of rtnl_dereference(). Signed-off-by: Vlad Buslov Reviewed-by: Stefano Brivio --- net/sched/cls_flower.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c index c04247b403ed..dcf3aee5697e 100644 --- a/net/sched/cls_flower.c +++ b/net/sched/cls_flower.c @@ -437,10 +437,20 @@ static void fl_hw_update_stats(struct tcf_proto *tp, struct cls_fl_filter *f) cls_flower.stats.lastused); } +static struct cls_fl_head *fl_head_dereference(struct tcf_proto *tp) +{ + /* Flower classifier only changes root pointer during init and destroy. + * Users must obtain reference to tcf_proto instance before calling its + * API, so tp->root pointer is protected from concurrent call to + * fl_destroy() by reference counting. + */ + return rcu_dereference_raw(tp->root); +} + static bool __fl_delete(struct tcf_proto *tp, struct cls_fl_filter *f, struct netlink_ext_ack *extack) { - struct cls_fl_head *head = rtnl_dereference(tp->root); + struct cls_fl_head *head = fl_head_dereference(tp); bool async = tcf_exts_get_net(&f->exts); bool last; @@ -472,7 +482,7 @@ static void fl_destroy_sleepable(struct work_struct *work) static void fl_destroy(struct tcf_proto *tp, bool rtnl_held, struct netlink_ext_ack *extack) { - struct cls_fl_head *head = rtnl_dereference(tp->root); + struct cls_fl_head *head = fl_head_dereference(tp); struct fl_flow_mask *mask, *next_mask; struct cls_fl_filter *f, *next; @@ -490,7 +500,7 @@ static void fl_destroy(struct tcf_proto *tp, bool rtnl_held, static void *fl_get(struct tcf_proto *tp, u32 handle) { - struct cls_fl_head *head = rtnl_dereference(tp->root); + struct cls_fl_head *head = fl_head_dereference(tp); return idr_find(&head->handle_idr, handle); } @@ -1308,7 +1318,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb, void **arg, bool ovr, bool rtnl_held, struct netlink_ext_ack *extack) { - struct cls_fl_head *head = rtnl_dereference(tp->root); + struct cls_fl_head *head = fl_head_dereference(tp); struct cls_fl_filter *fold = *arg; struct cls_fl_filter *fnew; struct fl_flow_mask *mask; @@ -1446,7 +1456,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb, static int fl_delete(struct tcf_proto *tp, void *arg, bool *last, bool rtnl_held, struct netlink_ext_ack *extack) { - struct cls_fl_head *head = rtnl_dereference(tp->root); + struct cls_fl_head *head = fl_head_dereference(tp); struct cls_fl_filter *f = arg; rhashtable_remove_fast(&f->mask->ht, &f->ht_node, @@ -1459,7 +1469,7 @@ static int fl_delete(struct tcf_proto *tp, void *arg, bool *last, static void fl_walk(struct tcf_proto *tp, struct tcf_walker *arg, bool rtnl_held) { - struct cls_fl_head *head = rtnl_dereference(tp->root); + struct cls_fl_head *head = fl_head_dereference(tp); struct cls_fl_filter *f; arg->count = arg->skip; @@ -1478,7 +1488,7 @@ static void fl_walk(struct tcf_proto *tp, struct tcf_walker *arg, static int fl_reoffload(struct tcf_proto *tp, bool add, tc_setup_cb_t *cb, void *cb_priv, struct netlink_ext_ack *extack) { - struct cls_fl_head *head = rtnl_dereference(tp->root); + struct cls_fl_head *head = fl_head_dereference(tp); struct tc_cls_flower_offload cls_flower = {}; struct tcf_block *block = tp->chain->block; struct fl_flow_mask *mask; -- 2.21.0