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Note: the removed READ_ONCE() is not needed because we only have to protect the locklessly reader in the different context (rps_may_expire_flow()). Signed-off-by: Jason Xing Reviewed-by: Eric Dumazet --- net/core/dev.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 854a3a28a8d8..58e0da91bfef 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4501,7 +4501,7 @@ set_rps_cpu(struct net_device *dev, struct sk_buff *skb, struct netdev_rx_queue *rxqueue; struct rps_dev_flow_table *flow_table; struct rps_dev_flow *old_rflow; - u32 flow_id; + u32 flow_id, head; u16 rxq_index; int rc; @@ -4529,8 +4529,8 @@ set_rps_cpu(struct net_device *dev, struct sk_buff *skb, old_rflow->filter = RPS_NO_FILTER; out: #endif - rflow->last_qtail = - READ_ONCE(per_cpu(softnet_data, next_cpu).input_queue_head); + head = READ_ONCE(per_cpu(softnet_data, next_cpu).input_queue_head); + rps_input_queue_tail_save(&rflow->last_qtail, head); } rflow->cpu = next_cpu; @@ -4613,7 +4613,7 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb, if (unlikely(tcpu != next_cpu) && (tcpu >= nr_cpu_ids || !cpu_online(tcpu) || ((int)(READ_ONCE(per_cpu(softnet_data, tcpu).input_queue_head) - - READ_ONCE(rflow->last_qtail))) >= 0)) { + rflow->last_qtail)) >= 0)) { tcpu = next_cpu; 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Signed-off-by: Jason Xing Reviewed-by: Eric Dumazet --- net/core/dev.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 58e0da91bfef..ed6efef01582 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4524,9 +4524,9 @@ set_rps_cpu(struct net_device *dev, struct sk_buff *skb, goto out; old_rflow = rflow; rflow = &flow_table->flows[flow_id]; - rflow->filter = rc; - if (old_rflow->filter == rflow->filter) - old_rflow->filter = RPS_NO_FILTER; + WRITE_ONCE(rflow->filter, rc); + if (old_rflow->filter == rc) + WRITE_ONCE(old_rflow->filter, RPS_NO_FILTER); out: #endif head = READ_ONCE(per_cpu(softnet_data, next_cpu).input_queue_head); @@ -4666,7 +4666,7 @@ bool rps_may_expire_flow(struct net_device *dev, u16 rxq_index, if (flow_table && flow_id <= flow_table->mask) { rflow = &flow_table->flows[flow_id]; cpu = READ_ONCE(rflow->cpu); - if (rflow->filter == filter_id && cpu < nr_cpu_ids && + if (READ_ONCE(rflow->filter) == filter_id && cpu < nr_cpu_ids && ((int)(READ_ONCE(per_cpu(softnet_data, cpu).input_queue_head) - READ_ONCE(rflow->last_qtail)) < (int)(10 * flow_table->mask))) From patchwork Thu Apr 18 07:36:03 2024 Content-Type: text/plain; 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Thu, 18 Apr 2024 00:36:17 -0700 (PDT) Received: from KERNELXING-MB0.tencent.com ([43.132.141.24]) by smtp.gmail.com with ESMTPSA id j9-20020a17090276c900b001e26ba8882fsm841756plt.287.2024.04.18.00.36.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Apr 2024 00:36:16 -0700 (PDT) From: Jason Xing To: edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, davem@davemloft.net, horms@kernel.org Cc: netdev@vger.kernel.org, kerneljasonxing@gmail.com, Jason Xing Subject: [PATCH net-next v3 3/3] net: rps: locklessly access rflow->cpu Date: Thu, 18 Apr 2024 15:36:03 +0800 Message-Id: <20240418073603.99336-4-kerneljasonxing@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20240418073603.99336-1-kerneljasonxing@gmail.com> References: <20240418073603.99336-1-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org From: Jason Xing This is the last member in struct rps_dev_flow which should be protected locklessly. So finish it. Signed-off-by: Jason Xing Reviewed-by: Eric Dumazet --- net/core/dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/dev.c b/net/core/dev.c index ed6efef01582..8010036c07b6 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4533,7 +4533,7 @@ set_rps_cpu(struct net_device *dev, struct sk_buff *skb, rps_input_queue_tail_save(&rflow->last_qtail, head); } - rflow->cpu = next_cpu; + WRITE_ONCE(rflow->cpu, next_cpu); return rflow; }