From patchwork Wed Jul 3 05:44:40 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ruifeng Wang X-Patchwork-Id: 55924 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 89C294D27; Wed, 3 Jul 2019 07:45:03 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id 7872A1BE0 for ; Wed, 3 Jul 2019 07:45:02 +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 C75D32B; Tue, 2 Jul 2019 22:45:01 -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 563563F718; Tue, 2 Jul 2019 22:46:53 -0700 (PDT) From: Ruifeng Wang To: vladimir.medvedkin@intel.com, bruce.richardson@intel.com Cc: dev@dpdk.org, honnappa.nagarahalli@arm.com, gavin.hu@arm.com, nd@arm.com, Ruifeng Wang Date: Wed, 3 Jul 2019 13:44:40 +0800 Message-Id: <20190703054441.30162-2-ruifeng.wang@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190703054441.30162-1-ruifeng.wang@arm.com> References: <20190703054441.30162-1-ruifeng.wang@arm.com> Subject: [dpdk-dev] [PATCH v4 2/3] 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. Besides, explicit structure alignment is used to address atomic operation building issue with older version clang. Suggested-by: Honnappa Nagarahalli Signed-off-by: Ruifeng Wang Reviewed-by: Honnappa Nagarahalli Reviewed-by: Gavin Hu --- v4: changed alignment attribute parameter v3: no changes v2: fixed clang building issue by supplying alignment attribute. lib/librte_lpm/rte_lpm.c | 32 +++++++++++++++++++++++++------- lib/librte_lpm/rte_lpm.h | 4 ++-- 2 files changed, 27 insertions(+), 9 deletions(-) diff --git a/lib/librte_lpm/rte_lpm.c b/lib/librte_lpm/rte_lpm.c index 6ec450a08..baa6e7460 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 +1323,15 @@ 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_tbl24_entry = { + .valid = INVALID, + .depth = 0, + .valid_group = 0, + }; + zero_tbl24_entry.next_hop = 0; + __atomic_store(&lpm->tbl24[i], + &zero_tbl24_entry, __ATOMIC_RELEASE); } else if (lpm->tbl24[i].valid_group == 1) { /* * If TBL24 entry is extended, then there has @@ -1365,7 +1376,8 @@ 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 +1659,11 @@ 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 +1674,11 @@ 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..906ec4483 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(sizeof(uint16_t)); __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(sizeof(uint16_t)); __extension__ struct rte_lpm_tbl_entry {