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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,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 CA178C3A5A2 for ; Fri, 23 Aug 2019 18:51:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC32A21874 for ; Fri, 23 Aug 2019 18:51:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406030AbfHWSvh (ORCPT ); Fri, 23 Aug 2019 14:51:37 -0400 Received: from mail-il-dmz.mellanox.com ([193.47.165.129]:44577 "EHLO mellanox.co.il" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2390902AbfHWSv0 (ORCPT ); Fri, 23 Aug 2019 14:51:26 -0400 Received: from Internal Mail-Server by MTLPINE1 (envelope-from vladbu@mellanox.com) with ESMTPS (AES256-SHA encrypted); 23 Aug 2019 21:51:19 +0300 Received: from reg-r-vrt-018-180.mtr.labs.mlnx. (reg-r-vrt-018-180.mtr.labs.mlnx [10.215.1.1]) by labmailer.mlnx (8.13.8/8.13.8) with ESMTP id x7NIpJEH012807; Fri, 23 Aug 2019 21:51:19 +0300 From: Vlad Buslov To: netdev@vger.kernel.org Cc: jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net, jakub.kicinski@netronome.com, pablo@netfilter.org, Vlad Buslov Subject: [PATCH net-next v2 06/10] net: sched: conditionally obtain rtnl lock in cls hw offloads API Date: Fri, 23 Aug 2019 21:50:52 +0300 Message-Id: <20190823185056.12536-7-vladbu@mellanox.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190823185056.12536-1-vladbu@mellanox.com> References: <20190823185056.12536-1-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 In order to remove dependency on rtnl lock from offloads code of classifiers, take rtnl lock conditionally before executing driver callbacks. Only obtain rtnl lock if block is bound to devices that require it. Block bind/unbind code is rtnl-locked and obtains block->cb_lock while holding rtnl lock. Obtain locks in same order in tc_setup_cb_*() functions to prevent deadlock. Signed-off-by: Vlad Buslov --- Changes from V1 to V2: - Speculatively read block->lockeddevcnt in tc_setup_cb_*() to obtain rtnl mutex without retry when block is bound to locked device. net/sched/cls_api.c | 65 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 87954f5370a4..f2dcecf34c6f 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -3076,11 +3076,28 @@ __tc_setup_cb_call(struct tcf_block *block, enum tc_setup_type type, int tc_setup_cb_call(struct tcf_block *block, enum tc_setup_type type, void *type_data, bool err_stop, bool rtnl_held) { + bool take_rtnl = READ_ONCE(block->lockeddevcnt); int ok_count; +retry: + if (take_rtnl) + rtnl_lock(); down_read(&block->cb_lock); + /* Need to obtain rtnl lock if block is bound to devs that require it. + * In block bind code cb_lock is obtained while holding rtnl, so we must + * obtain the locks in same order here. + */ + if (!rtnl_held && !take_rtnl && block->lockeddevcnt) { + up_read(&block->cb_lock); + take_rtnl = true; + goto retry; + } + ok_count = __tc_setup_cb_call(block, type, type_data, err_stop); + up_read(&block->cb_lock); + if (take_rtnl) + rtnl_unlock(); return ok_count; } EXPORT_SYMBOL(tc_setup_cb_call); @@ -3095,9 +3112,23 @@ int tc_setup_cb_add(struct tcf_block *block, struct tcf_proto *tp, enum tc_setup_type type, void *type_data, bool err_stop, u32 *flags, unsigned int *in_hw_count, bool rtnl_held) { + bool take_rtnl = READ_ONCE(block->lockeddevcnt); int ok_count; +retry: + if (take_rtnl) + rtnl_lock(); down_read(&block->cb_lock); + /* Need to obtain rtnl lock if block is bound to devs that require it. + * In block bind code cb_lock is obtained while holding rtnl, so we must + * obtain the locks in same order here. + */ + if (!rtnl_held && !take_rtnl && block->lockeddevcnt) { + up_read(&block->cb_lock); + take_rtnl = true; + goto retry; + } + /* Make sure all netdevs sharing this block are offload-capable. */ if (block->nooffloaddevcnt && err_stop) { ok_count = -EOPNOTSUPP; @@ -3115,6 +3146,8 @@ int tc_setup_cb_add(struct tcf_block *block, struct tcf_proto *tp, ok_count, true); err_unlock: up_read(&block->cb_lock); + if (take_rtnl) + rtnl_unlock(); return ok_count < 0 ? ok_count : 0; } EXPORT_SYMBOL(tc_setup_cb_add); @@ -3131,9 +3164,23 @@ int tc_setup_cb_replace(struct tcf_block *block, struct tcf_proto *tp, u32 *new_flags, unsigned int *new_in_hw_count, bool rtnl_held) { + bool take_rtnl = READ_ONCE(block->lockeddevcnt); int ok_count; +retry: + if (take_rtnl) + rtnl_lock(); down_read(&block->cb_lock); + /* Need to obtain rtnl lock if block is bound to devs that require it. + * In block bind code cb_lock is obtained while holding rtnl, so we must + * obtain the locks in same order here. + */ + if (!rtnl_held && !take_rtnl && block->lockeddevcnt) { + up_read(&block->cb_lock); + take_rtnl = true; + goto retry; + } + /* Make sure all netdevs sharing this block are offload-capable. */ if (block->nooffloaddevcnt && err_stop) { ok_count = -EOPNOTSUPP; @@ -3155,6 +3202,8 @@ int tc_setup_cb_replace(struct tcf_block *block, struct tcf_proto *tp, new_flags, ok_count, true); err_unlock: up_read(&block->cb_lock); + if (take_rtnl) + rtnl_unlock(); return ok_count < 0 ? ok_count : 0; } EXPORT_SYMBOL(tc_setup_cb_replace); @@ -3167,9 +3216,23 @@ int tc_setup_cb_destroy(struct tcf_block *block, struct tcf_proto *tp, enum tc_setup_type type, void *type_data, bool err_stop, u32 *flags, unsigned int *in_hw_count, bool rtnl_held) { + bool take_rtnl = READ_ONCE(block->lockeddevcnt); int ok_count; +retry: + if (take_rtnl) + rtnl_lock(); down_read(&block->cb_lock); + /* Need to obtain rtnl lock if block is bound to devs that require it. + * In block bind code cb_lock is obtained while holding rtnl, so we must + * obtain the locks in same order here. + */ + if (!rtnl_held && !take_rtnl && block->lockeddevcnt) { + up_read(&block->cb_lock); + take_rtnl = true; + goto retry; + } + ok_count = __tc_setup_cb_call(block, type, type_data, err_stop); tc_cls_offload_cnt_reset(block, tp, in_hw_count, flags); @@ -3177,6 +3240,8 @@ int tc_setup_cb_destroy(struct tcf_block *block, struct tcf_proto *tp, tp->ops->hw_del(tp, type_data); up_read(&block->cb_lock); + if (take_rtnl) + rtnl_unlock(); return ok_count < 0 ? ok_count : 0; } EXPORT_SYMBOL(tc_setup_cb_destroy); -- 2.21.0