From patchwork Thu Jun 27 09:37:51 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ruifeng Wang X-Patchwork-Id: 55463 X-Patchwork-Delegate: thomas@monjalon.net Return-Path: X-Original-To: patchwork@dpdk.org Delivered-To: patchwork@dpdk.org Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 388CF4CA6; Thu, 27 Jun 2019 11:38:27 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id D59DF49DF for ; Thu, 27 Jun 2019 11:38:25 +0200 (CEST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5959C2B; Thu, 27 Jun 2019 02:38:25 -0700 (PDT) Received: from net-arm-c2400-02.shanghai.arm.com (net-arm-c2400-02.shanghai.arm.com [10.169.40.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C23283F718; Thu, 27 Jun 2019 02:38:23 -0700 (PDT) From: Ruifeng Wang To: bruce.richardson@intel.com, vladimir.medvedkin@intel.com Cc: dev@dpdk.org, honnappa.nagarahalli@arm.com, gavin.hu@arm.com, nd@arm.com, Ruifeng Wang Date: Thu, 27 Jun 2019 17:37:51 +0800 Message-Id: <20190627093751.7746-3-ruifeng.wang@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190627093751.7746-1-ruifeng.wang@arm.com> References: <20190627093751.7746-1-ruifeng.wang@arm.com> Subject: [dpdk-dev] [PATCH v3 3/3] lib/lpm: memory orderings to avoid race conditions for v20 X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" When a tbl8 group is getting attached to a tbl24 entry, lookup might fail even though the entry is configured in the table. For ex: consider a LPM table configured with 10.10.10.1/24. When a new entry 10.10.10.32/28 is being added, a new tbl8 group is allocated and tbl24 entry is changed to point to the tbl8 group. If the tbl24 entry is written without the tbl8 group entries updated, a lookup on 10.10.10.9 will return failure. Correct memory orderings are required to ensure that the store to tbl24 does not happen before the stores to tbl8 group entries complete. Suggested-by: Honnappa Nagarahalli Signed-off-by: Ruifeng Wang Reviewed-by: Honnappa Nagarahalli Reviewed-by: Gavin Hu --- v3: no changes v2: fixed clang building issue by supplying alignment attribute. v1: initail version lib/librte_lpm/rte_lpm.c | 31 ++++++++++++++++++++++++------- lib/librte_lpm/rte_lpm.h | 4 ++-- 2 files changed, 26 insertions(+), 9 deletions(-) diff --git a/lib/librte_lpm/rte_lpm.c b/lib/librte_lpm/rte_lpm.c index fabd13fb0..5f8d494ae 100644 --- a/lib/librte_lpm/rte_lpm.c +++ b/lib/librte_lpm/rte_lpm.c @@ -737,7 +737,8 @@ add_depth_small_v20(struct rte_lpm_v20 *lpm, uint32_t ip, uint8_t depth, /* Setting tbl24 entry in one go to avoid race * conditions */ - lpm->tbl24[i] = new_tbl24_entry; + __atomic_store(&lpm->tbl24[i], &new_tbl24_entry, + __ATOMIC_RELEASE); continue; } @@ -892,7 +893,8 @@ add_depth_big_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked, uint8_t depth, .depth = 0, }; - lpm->tbl24[tbl24_index] = new_tbl24_entry; + __atomic_store(&lpm->tbl24[tbl24_index], &new_tbl24_entry, + __ATOMIC_RELEASE); } /* If valid entry but not extended calculate the index into Table8. */ else if (lpm->tbl24[tbl24_index].valid_group == 0) { @@ -938,7 +940,8 @@ add_depth_big_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked, uint8_t depth, .depth = 0, }; - lpm->tbl24[tbl24_index] = new_tbl24_entry; + __atomic_store(&lpm->tbl24[tbl24_index], &new_tbl24_entry, + __ATOMIC_RELEASE); } else { /* * If it is valid, extended entry calculate the index into tbl8. @@ -1320,7 +1323,14 @@ delete_depth_small_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked, if (lpm->tbl24[i].valid_group == 0 && lpm->tbl24[i].depth <= depth) { - lpm->tbl24[i].valid = INVALID; + struct rte_lpm_tbl_entry_v20 zero_tbl_entry = { + .valid = INVALID, + .depth = 0, + .valid_group = 0, + }; + zero_tbl_entry.next_hop = 0; + __atomic_store(&lpm->tbl24[i], &zero_tbl_entry, + __ATOMIC_RELEASE); } else if (lpm->tbl24[i].valid_group == 1) { /* * If TBL24 entry is extended, then there has @@ -1365,7 +1375,8 @@ delete_depth_small_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked, if (lpm->tbl24[i].valid_group == 0 && lpm->tbl24[i].depth <= depth) { - lpm->tbl24[i] = new_tbl24_entry; + __atomic_store(&lpm->tbl24[i], &new_tbl24_entry, + __ATOMIC_RELEASE); } else if (lpm->tbl24[i].valid_group == 1) { /* * If TBL24 entry is extended, then there has @@ -1647,8 +1658,11 @@ delete_depth_big_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked, tbl8_recycle_index = tbl8_recycle_check_v20(lpm->tbl8, tbl8_group_start); if (tbl8_recycle_index == -EINVAL) { - /* Set tbl24 before freeing tbl8 to avoid race condition. */ + /* Set tbl24 before freeing tbl8 to avoid race condition. + * Prevent the free of the tbl8 group from hoisting. + */ lpm->tbl24[tbl24_index].valid = 0; + __atomic_thread_fence(__ATOMIC_RELEASE); tbl8_free_v20(lpm->tbl8, tbl8_group_start); } else if (tbl8_recycle_index > -1) { /* Update tbl24 entry. */ @@ -1659,8 +1673,11 @@ delete_depth_big_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked, .depth = lpm->tbl8[tbl8_recycle_index].depth, }; - /* Set tbl24 before freeing tbl8 to avoid race condition. */ + /* Set tbl24 before freeing tbl8 to avoid race condition. + * Prevent the free of the tbl8 group from hoisting. + */ lpm->tbl24[tbl24_index] = new_tbl24_entry; + __atomic_thread_fence(__ATOMIC_RELEASE); tbl8_free_v20(lpm->tbl8, tbl8_group_start); } diff --git a/lib/librte_lpm/rte_lpm.h b/lib/librte_lpm/rte_lpm.h index 6f5704c5c..98c70ecbe 100644 --- a/lib/librte_lpm/rte_lpm.h +++ b/lib/librte_lpm/rte_lpm.h @@ -88,7 +88,7 @@ struct rte_lpm_tbl_entry_v20 { */ uint8_t valid_group :1; uint8_t depth :6; /**< Rule depth. */ -}; +} __rte_aligned(2); __extension__ struct rte_lpm_tbl_entry { @@ -121,7 +121,7 @@ struct rte_lpm_tbl_entry_v20 { uint8_t group_idx; uint8_t next_hop; }; -}; +} __rte_aligned(2); __extension__ struct rte_lpm_tbl_entry {