From patchwork Thu Apr 18 07:36:01 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Xing X-Patchwork-Id: 13634280 X-Patchwork-Delegate: kuba@kernel.org Received: from mail-pl1-f179.google.com (mail-pl1-f179.google.com [209.85.214.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8AC7556462 for ; Thu, 18 Apr 2024 07:36:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.179 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713425773; cv=none; b=XH2QuZJjzqcoqMBEqYFD8ZNC76UtZuhfhNq9ISeir7PCTlbpSsSxn01Xz9fvuluRI6/oPG/dQiTKFUkiCWSohzVi82InslI0H2Pbbta5HTmYK+qSoZj8vBrGD92zRheWrkLZjUz+U0xjmFjqytsShUFzfeP/gjmgA0h8AjNFtCU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713425773; c=relaxed/simple; bh=SOjRjeUJDoa9oFT1O0p4M4FPxZCcohSdrD5qjmQkkRM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=TryfS5EQHNtQk+3HPXwO5IRRp3j+oObKm4rSpaxGW/ECWIjI/PLQlD2/QbF5BLdHImDZB35lxvBAz2a4HviN0a8d8Iiqjse8cJrWP9l5HbwuKGT8nztmnOsg06GvpZuc6qvclxc+GtR6X2GwLy1uhvmLWNJ+jLvgmV1ruztrKFM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=H2SAwwXy; arc=none smtp.client-ip=209.85.214.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="H2SAwwXy" Received: by mail-pl1-f179.google.com with SMTP id d9443c01a7336-1e3c3aa8938so4398365ad.1 for ; Thu, 18 Apr 2024 00:36:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1713425772; x=1714030572; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=oqMygDrTMWROWwU+4nXqwtf7JivSIp3ISM3CYmYtTDM=; b=H2SAwwXypeesnkAttAMt7Olq5enFFpwdzmktBzB00tvFNOcq9PNGyM4sPQx2sf4bLn k9noKwLQJKNQL30jpUmfrM8GYI9Zcqo0lVyaXs0fUeqCjb+U0Mn5oPyiwICZTQ4wuitz k+QkFOMuJE9m6BwS6WtKAm3sR5f7+idhPpXg3jAU9/5gqQ0O5hGDtY7Y0rmP1Ox0olNq GmCNY/e3W7WHO6woLc3b4nAFxyQKJjp/pB2V67VcvXfaEf46YAP80iZMaElEEN2FRNxU A7qNMN0y7A2i8IfSF6IB1ROfLW4L2aMJbFWKrREx8yhFilhIW6zzlXlZ3P/yjC4zg1m6 Aq0w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1713425772; x=1714030572; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=oqMygDrTMWROWwU+4nXqwtf7JivSIp3ISM3CYmYtTDM=; b=gMElbBr5SMFSgq1gd86JYhQyk3mfNDXYEvjxn5TgEw8TYyeWIXHt1W627bUykcLg97 QWpQte9r2w3epcGDjykL/EPtRrO1nd1LzXBh+5fAGkWlbLOWG+bmJOMBGnVNW0/mQSa7 YG7GpsV2v75BnAFyGVzSR7IvHpaCgVtoM13GRWXjTml8QP+0bK5Sz0fEjRSoq9cae2Tc 2l2un7nT9a5A0Z/hD4rPPkSmpNYic4CN3CUUpVy8u1PTMpTdfpHjmlsJgkuiEdO/59h1 /6xuOf2Di51iIboAKXE231sP0bIKS2s9sc1T99zAzpMADoVd+qTuijDU+WXJMRTrOBOO Vb6Q== X-Gm-Message-State: AOJu0YzN26kSrYM+GLLFR9dvjg9wOe+iezt9JZC/pe9f50IfySDrjGDL EXq+L3QCfW21Wy+VU6dOowBHTPyY0tUkpheLnybrbXGTJx5hq2yD X-Google-Smtp-Source: AGHT+IEXKnYVhqazbZhTC7VnTwjNePPdZajzKVglHC3nuavD1CEgxOQ0t3x3ItmPNixcMszAQN4Ufg== X-Received: by 2002:a17:902:e843:b0:1e4:b1a2:b40c with SMTP id t3-20020a170902e84300b001e4b1a2b40cmr2599413plg.42.1713425771690; Thu, 18 Apr 2024 00:36:11 -0700 (PDT) Received: from KERNELXING-MB0.tencent.com ([43.132.141.24]) by smtp.gmail.com with ESMTPSA id j9-20020a17090276c900b001e26ba8882fsm841756plt.287.2024.04.18.00.36.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Apr 2024 00:36:11 -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 1/3] net: rps: protect last_qtail with rps_input_queue_tail_save() helper Date: Thu, 18 Apr 2024 15:36:01 +0800 Message-Id: <20240418073603.99336-2-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 Removing one unnecessary reader protection and add another writer protection to finish the locklessly proctection job. 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; rflow = set_rps_cpu(dev, skb, rflow, next_cpu); }