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 55E49C43219 for ; Sun, 20 Nov 2022 17:19:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229732AbiKTRTM (ORCPT ); Sun, 20 Nov 2022 12:19:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44754 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229553AbiKTRTK (ORCPT ); Sun, 20 Nov 2022 12:19:10 -0500 Received: from smtp.smtpout.orange.fr (smtp-21.smtpout.orange.fr [80.12.242.21]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C3D0C23168 for ; Sun, 20 Nov 2022 09:19:09 -0800 (PST) Received: from pop-os.home ([86.243.100.34]) by smtp.orange.fr with ESMTPA id wnyBohc3Ubw2uwnyFoEd9Y; Sun, 20 Nov 2022 18:19:07 +0100 X-ME-Helo: pop-os.home X-ME-Auth: Y2hyaXN0b3BoZS5qYWlsbGV0QHdhbmFkb28uZnI= X-ME-Date: Sun, 20 Nov 2022 18:19:07 +0100 X-ME-IP: 86.243.100.34 From: Christophe JAILLET To: "Rafael J. Wysocki" , Viresh Kumar , Thierry Reding , Jonathan Hunter Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Christophe JAILLET , linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org Subject: [PATCH] cpufreq: tegra186: Use flexible array to simplify memory allocation Date: Sun, 20 Nov 2022 18:19:02 +0100 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use flexible array to simplify memory allocation. It saves some memory, avoids an indirection when reading the 'clusters' array and removes some LoC. Detailed explanation: ==================== Knowing that: - each devm_ allocation over-allocates 40 bytes for internal needs - Some rounding is done by the memory allocator on 8, 16, 32, 64, 96, 128, 192, 256, 512, 1024, 2048, 4096, 8192 boundaries and that: - sizeof(struct tegra186_cpufreq_data) = 24 - sizeof(struct tegra186_cpufreq_cluster) = 16 Memory allocations in tegra186_cpufreq_probe() are: data: (24 + 40) = 64 => 64 bytes data->clusters: (2 * 16 + 40) = 72 => 96 bytes So a total of 160 bytes are allocated. 56 for the real need, 80 for internal uses and 24 are wasted. If 'struct tegra186_cpufreq_data' is reordered so that 'clusters' is a flexible array: - it saves one pointer in the structure - only one allocation is needed So, only 96 bytes are allocated: 16 + 2 * 16 + 40 = 88 => 96 bytes Signed-off-by: Christophe JAILLET --- Compile tested only --- drivers/cpufreq/tegra186-cpufreq.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/drivers/cpufreq/tegra186-cpufreq.c b/drivers/cpufreq/tegra186-cpufreq.c index 6c88827f4e62..f98f53bf1011 100644 --- a/drivers/cpufreq/tegra186-cpufreq.c +++ b/drivers/cpufreq/tegra186-cpufreq.c @@ -65,8 +65,8 @@ struct tegra186_cpufreq_cluster { struct tegra186_cpufreq_data { void __iomem *regs; - struct tegra186_cpufreq_cluster *clusters; const struct tegra186_cpufreq_cpu *cpus; + struct tegra186_cpufreq_cluster clusters[]; }; static int tegra186_cpufreq_init(struct cpufreq_policy *policy) @@ -221,15 +221,12 @@ static int tegra186_cpufreq_probe(struct platform_device *pdev) struct tegra_bpmp *bpmp; unsigned int i = 0, err; - data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + data = devm_kzalloc(&pdev->dev, + struct_size(data, clusters, TEGRA186_NUM_CLUSTERS), + GFP_KERNEL); if (!data) return -ENOMEM; - data->clusters = devm_kcalloc(&pdev->dev, TEGRA186_NUM_CLUSTERS, - sizeof(*data->clusters), GFP_KERNEL); - if (!data->clusters) - return -ENOMEM; - data->cpus = tegra186_cpus; bpmp = tegra_bpmp_get(&pdev->dev); -- 2.34.1