Received: by 2002:a25:868d:0:0:0:0:0 with SMTP id z13csp477946ybk; Fri, 15 May 2020 05:50:14 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwV0r8P8K3LzZrFY+v2RI3QTy6dIQjv19WnnYrjGy0OblvXIr12d3whCZdxQcEFTAlE5hzN X-Received: by 2002:aa7:d3d6:: with SMTP id o22mr2705994edr.359.1589547014163; Fri, 15 May 2020 05:50:14 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1589547014; cv=none; d=google.com; s=arc-20160816; b=g4ScbW5lqdVvxwC/Dbjc/oWl6iII/MucW8xHSue8IWvUNh7hGBXaQaXXhw58/+2W2b DTEkmApi0OYWRKpMoH3ouAQVe/jwOEODy2yJq5vi+ZBc6sObDL7+Zk5iQJ2U68GZqnmt hE5WApjFrhsPAl73ZG4HSteAkYYSFuW2eg39Q1+fgYdN8JEHNLHYQR2AYAbtBAbUF1Lw Wu7/uBv5X3xEjOtI8W+bhkBwhelU/SOB3PiL8EVr+Fwxy2kg/nlHLPyM4qYl0GLVQ4BO 1xkr6FoWCf4AThoS6qaB1jpu1JOsCy1u8VcvlQV5nwuaPgj6BcMsae/eTQzNDUW2qQeQ 61dg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from; bh=4o5ySE7jAXM5mRi6F3D+exwLiAHZeHxIDf+fssEpfl8=; b=0067uV9f6oGSLbMAfAbTWECWzG6PPz63qVMo/rCXG66oD21WDRvDQqYZL/FD6YqZ2n ODtwWS9naR6lJpE8p2mGOpq9Vjx3RVrErQpHXv+RVUC3wVPryujAhVeEGq2cgoSea76L kNYfXOy/XFf+3bVx9EKPc/uEqfSjTOqXqyx2OOzXwWsZYcjdk2tMY5xHeW1/+Lrw+PU2 bJaPgPZkiu9TZr1EiLIdK8Y2BrnsefvyePBflaWnnzW6waWwngub/Nr7XChNlfAec3rN YNs97C44mV2E8czaNfoNlm4kCf/+dYmRVr8aESHR/yx4NFVRIdIPa+GiAzgUdvC1es9k BsAg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=alibaba.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id pk16si1096250ejb.310.2020.05.15.05.49.51; Fri, 15 May 2020 05:50:14 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=alibaba.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726234AbgEOMrb (ORCPT + 99 others); Fri, 15 May 2020 08:47:31 -0400 Received: from out30-54.freemail.mail.aliyun.com ([115.124.30.54]:51733 "EHLO out30-54.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726140AbgEOMrb (ORCPT ); Fri, 15 May 2020 08:47:31 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R891e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07488;MF=laijs@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0TycgwXZ_1589546835; Received: from localhost(mailfrom:laijs@linux.alibaba.com fp:SMTPD_---0TycgwXZ_1589546835) by smtp.aliyun-inc.com(127.0.0.1); Fri, 15 May 2020 20:47:15 +0800 From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: Lai Jiangshan , Peter Zijlstra , "Paul E . McKenney" , Oleg Nesterov , Michel Lespinasse , Andrea Arcangeli , David Woodhouse , Rik van Riel , Mathieu Desnoyers Subject: [PATCH 2/2] rbtree_latch: don't need to check seq when it found a node Date: Fri, 15 May 2020 12:47:07 +0000 Message-Id: <20200515124710.16439-2-laijs@linux.alibaba.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200515124710.16439-1-laijs@linux.alibaba.com> References: <20200515124710.16439-1-laijs@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org latch_tree_find() should be protected by caller via RCU or so. When it find a node in an attempt, the node must be a valid one. Cc: Peter Zijlstra Cc: Paul E. McKenney Cc: Oleg Nesterov Cc: Michel Lespinasse Cc: Andrea Arcangeli Cc: David Woodhouse Cc: Rik van Riel Cc: Mathieu Desnoyers Signed-off-by: Lai Jiangshan --- include/linux/rbtree_latch.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/rbtree_latch.h b/include/linux/rbtree_latch.h index b012bd95eabf..09a3c05d1c5b 100644 --- a/include/linux/rbtree_latch.h +++ b/include/linux/rbtree_latch.h @@ -208,7 +208,7 @@ latch_tree_find(void *key, struct latch_tree_root *root, do { seq = raw_read_seqcount_latch(&root->seq); node = __lt_find(key, root, seq & 1, ops->comp); - } while (read_seqcount_retry(&root->seq, seq)); + } while (!node && read_seqcount_retry(&root->seq, seq)); return node; } -- 2.20.1