From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A2E8C433EF for ; Tue, 23 Nov 2021 18:58:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231643AbhKWTBw (ORCPT ); Tue, 23 Nov 2021 14:01:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41730 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230197AbhKWTBw (ORCPT ); Tue, 23 Nov 2021 14:01:52 -0500 Received: from mail-il1-x132.google.com (mail-il1-x132.google.com [IPv6:2607:f8b0:4864:20::132]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CDE63C061574 for ; Tue, 23 Nov 2021 10:58:43 -0800 (PST) Received: by mail-il1-x132.google.com with SMTP id j7so33749ilk.13 for ; Tue, 23 Nov 2021 10:58:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=jsTPCCOIpmIL1a5Q1LdHjXMSuDgKbZ1B3NL6RXNxgaI=; b=YugQ8mNXY9oZTvMGkqv0XTeNFHhiIV0+JkMYKalxzpwan8lDUwM6/YaSFXka3/d4HI p3NMC33WS7EsyFtNxXpTYDFw9J+uGAm0bkynxk4NcGpotqVv/Lb/eGvcZb+mErmSJKTk ojcy7cTw37bGxalx4CLe5HGtmfU3Hujo7Qog/tPenKVLixXbhFatcKreOl6UcmqbwRUb PPCNbYx3j6eWktr6uSciTOe6ONUxjmklV0JPaFKyDctHnoIwqnSAgXjhKtaUOFozVh8+ JubuntHnktGXcNMWHbHqufHDGxfiruhclB5Cn5ZNj2rw/4QNlTxWjbuech2EFjcK5DMG WVCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=jsTPCCOIpmIL1a5Q1LdHjXMSuDgKbZ1B3NL6RXNxgaI=; b=QV4Qa2un94aokdzVUEAGBvnRRCGvd4l/DVXGiLq2Tjqz3lrBJbSBjS9VcuynF3mmzd q3kOWtsK47hpFwHzBT7r08tN8JDhKcB3d45QRLVnbvYOn8hQ6lqAmS1GF99XqTCEmPlk d6BZcQ+rjSqDdY8JxjVnNWfOUqQQN/OgzTKhRKZEaGa81KqTK/G5Anw44A8hPb5Pm0oz 4Qp/Y3IdV1cjaB9hzMadeKz3ML2kjclh3DBSlcFNqfNk9AenATQxAFonG8cTZYI0Zo7b W2G9hQlp8Kvnni9xgnsHpmxSTHsD2drA6z7A1CUFnECzAGpsuKCrCTOnnA+HC0gvjcLo 9oHw== X-Gm-Message-State: AOAM532Vh5SLguqtjbk0Wiedc4Q0DAUP45vZjlKIwF5ZFzi2Fp8iW6Er xlaLxx+Sbk5qoWN/01D43g5itCO7b6/2vbTu X-Google-Smtp-Source: ABdhPJx5lQSvpeqMq+6MIYUlOSCztTxzPemv+agTx8X+tzRVEPqaNGkm1KyG/LoMSpzzAxhjENwh6Q== X-Received: by 2002:a92:c14a:: with SMTP id b10mr7378654ilh.161.1637693923025; Tue, 23 Nov 2021 10:58:43 -0800 (PST) Received: from [192.168.1.30] ([207.135.234.126]) by smtp.gmail.com with ESMTPSA id k7sm5507244iov.40.2021.11.23.10.58.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Nov 2021 10:58:42 -0800 (PST) Subject: Re: [PATCH 3/3] block: only allocate poll_stats if there's a user of them To: Christoph Hellwig Cc: linux-block@vger.kernel.org References: <20211123171058.346084-1-axboe@kernel.dk> <20211123171058.346084-4-axboe@kernel.dk> From: Jens Axboe Message-ID: Date: Tue, 23 Nov 2021 11:58:42 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 11/23/21 11:50 AM, Christoph Hellwig wrote: >> + spin_lock_irq(&q->stats->lock); >> + if (q->poll_stat) { >> + spin_unlock_irq(&q->stats->lock); >> + kfree(poll_stat); >> + return true; >> + } >> + q->poll_stat = poll_stat; >> + spin_unlock_irq(&q->stats->lock); > > If we'd use a cmpxchg to install the pointer we could keep the > blk_queue_stats definition private. How about we just move this alloc+enable logic into blk-stat.c instead? -- Jens Axboe