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 X-Spam-Level: X-Spam-Status: No, score=-9.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E896C67863 for ; Wed, 24 Oct 2018 03:15:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 454492075D for ; Wed, 24 Oct 2018 03:15:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Oq9hBHjf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 454492075D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-clk-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725998AbeJXLld (ORCPT ); Wed, 24 Oct 2018 07:41:33 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:44422 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725952AbeJXLlc (ORCPT ); Wed, 24 Oct 2018 07:41:32 -0400 Received: by mail-pg1-f194.google.com with SMTP id w3-v6so1614401pgs.11 for ; Tue, 23 Oct 2018 20:15:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=sLIRKsPeonK/zKq59N3XJK3GG96UNWulOAZhs9ex8SY=; b=Oq9hBHjfqen+WJ1439fJed/MhzNLjcC79qA5qQHQAIMzaws1C8fAIf3VfOarEvwhWT r5J0q+QWxIrpKpO+5x8i/nZxWbf/4AY1bcFhLVCiKwSzy3gcM8vMH0Bp0p7QpIAlXrvQ b6nIHrhDtzRLebe1aQipDiaNzS22jPD9vdXOk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=sLIRKsPeonK/zKq59N3XJK3GG96UNWulOAZhs9ex8SY=; b=DVwjV6j8fkVkYVzbmWVTd7DHhKhQy15euFhRoaGKF4rv6GRNZk9Sx92EHdWXXGJOZO 2AhRvYJiu002iz3pOkNe+hxxPyfAzEsJdLSma6GFHPCQVHqCxDcH4Pob9VM/2TBf89U2 NuewiWO6us/oDu4uO4GQcVfQJzclixhWT6FKCyhtQGb8JrDgv/NuINXSIbyFU6bf8ZOq gMI+N2IkA9geN4TcMLSzeZGr2rCVPc5Unpr/29qK2YYSIuuuPkVwB/B7mM41AdEi1DwQ 7+fUMCGGrA36L82rNM1tuWSpihrBqDq7+RRU9dy0by31B1QzWRD53RGutq7M5hGXLpo+ +OPA== X-Gm-Message-State: AGRZ1gIR99UnwTfr3xCXZ+z6GUzzvFGytOovAmqYYnXPxCepxRYXcrxE +svnfJy1O5XY104PBXtHqSVhHFLZRI8= X-Google-Smtp-Source: AJdET5dNnQkWHsNuX1YpS5kddgO8he+p0IDdFMXZpwCjVhiBwvyf1ZDsSHKsxalh3KxPcd51MJp1CA== X-Received: by 2002:a63:fa4e:: with SMTP id g14-v6mr640117pgk.18.1540344702043; Tue, 23 Oct 2018 18:31:42 -0700 (PDT) Received: from exogeni.mtv.corp.google.com ([2620:15c:202:1:5e2b:39df:72ed:4968]) by smtp.gmail.com with ESMTPSA id p4-v6sm3882341pfg.188.2018.10.23.18.31.40 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Oct 2018 18:31:41 -0700 (PDT) From: Derek Basehore To: linux-kernel@vger.kernel.org Cc: linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-doc@vger.kernel.org, sboyd@kernel.org, mturquette@baylibre.com, heiko@sntech.de, aisheng.dong@nxp.com, mchehab+samsung@kernel.org, corbet@lwn.net, Stephen Boyd , Jerome Brunet , Derek Basehore Subject: [PATCH 1/6] clk: Remove recursion in clk_core_{prepare,enable}() Date: Tue, 23 Oct 2018 18:31:27 -0700 Message-Id: <20181024013132.115907-2-dbasehore@chromium.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181024013132.115907-1-dbasehore@chromium.org> References: <20181024013132.115907-1-dbasehore@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-clk-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org From: Stephen Boyd Enabling and preparing clocks can be written quite naturally with recursion. We start at some point in the tree and recurse up the tree to find the oldest parent clk that needs to be enabled or prepared. Then we enable/prepare and return to the caller, going back to the clk we started at and enabling/preparing along the way. The problem is recursion isn't great for kernel code where we have a limited stack size. Furthermore, we may be calling this code inside clk_set_rate() which also has recursion in it, so we're really not looking good if we encounter a tall clk tree. Let's create a stack instead by looping over the parent chain and collecting clks of interest. Then the enable/prepare becomes as simple as iterating over that list and calling enable. Cc: Jerome Brunet Signed-off-by: Stephen Boyd Signed-off-by: Derek Basehore --- drivers/clk/clk.c | 113 ++++++++++++++++++++++++++-------------------- 1 file changed, 64 insertions(+), 49 deletions(-) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index af011974d4ec..95d818f5edb2 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -71,6 +71,8 @@ struct clk_core { struct hlist_head children; struct hlist_node child_node; struct hlist_head clks; + struct list_head prepare_list; + struct list_head enable_list; unsigned int notifier_count; #ifdef CONFIG_DEBUG_FS struct dentry *dentry; @@ -740,49 +742,48 @@ EXPORT_SYMBOL_GPL(clk_unprepare); static int clk_core_prepare(struct clk_core *core) { int ret = 0; + struct clk_core *tmp, *parent; + LIST_HEAD(head); lockdep_assert_held(&prepare_lock); - if (!core) - return 0; + while (core) { + list_add(&core->prepare_list, &head); + /* Stop once we see a clk that is already prepared */ + if (core->prepare_count) + break; + core = core->parent; + } - if (core->prepare_count == 0) { - ret = clk_pm_runtime_get(core); - if (ret) - return ret; + list_for_each_entry_safe(core, tmp, &head, prepare_list) { + list_del_init(&core->prepare_list); - ret = clk_core_prepare(core->parent); - if (ret) - goto runtime_put; + if (core->prepare_count == 0) { + ret = clk_pm_runtime_get(core); + if (ret) + goto err; - trace_clk_prepare(core); + trace_clk_prepare(core); - if (core->ops->prepare) - ret = core->ops->prepare(core->hw); + if (core->ops->prepare) + ret = core->ops->prepare(core->hw); - trace_clk_prepare_complete(core); + trace_clk_prepare_complete(core); - if (ret) - goto unprepare; + if (ret) { + clk_pm_runtime_put(core); + goto err; + } + } + core->prepare_count++; } - core->prepare_count++; - - /* - * CLK_SET_RATE_GATE is a special case of clock protection - * Instead of a consumer claiming exclusive rate control, it is - * actually the provider which prevents any consumer from making any - * operation which could result in a rate change or rate glitch while - * the clock is prepared. - */ - if (core->flags & CLK_SET_RATE_GATE) - clk_core_rate_protect(core); - return 0; -unprepare: - clk_core_unprepare(core->parent); -runtime_put: - clk_pm_runtime_put(core); +err: + parent = core->parent; + list_for_each_entry_safe_continue(core, tmp, &head, prepare_list) + list_del_init(&core->prepare_list); + clk_core_unprepare(parent); return ret; } @@ -878,37 +879,49 @@ EXPORT_SYMBOL_GPL(clk_disable); static int clk_core_enable(struct clk_core *core) { int ret = 0; + struct clk_core *tmp, *parent; + LIST_HEAD(head); lockdep_assert_held(&enable_lock); - if (!core) - return 0; - - if (WARN(core->prepare_count == 0, - "Enabling unprepared %s\n", core->name)) - return -ESHUTDOWN; + while (core) { + list_add(&core->enable_list, &head); + /* Stop once we see a clk that is already enabled */ + if (core->enable_count) + break; + core = core->parent; + } - if (core->enable_count == 0) { - ret = clk_core_enable(core->parent); + list_for_each_entry_safe(core, tmp, &head, enable_list) { + list_del_init(&core->enable_list); - if (ret) - return ret; + if (WARN_ON(core->prepare_count == 0)) { + ret = -ESHUTDOWN; + goto err; + } - trace_clk_enable_rcuidle(core); + if (core->enable_count == 0) { + trace_clk_enable_rcuidle(core); - if (core->ops->enable) - ret = core->ops->enable(core->hw); + if (core->ops->enable) + ret = core->ops->enable(core->hw); - trace_clk_enable_complete_rcuidle(core); + trace_clk_enable_complete_rcuidle(core); - if (ret) { - clk_core_disable(core->parent); - return ret; + if (ret) + goto err; } + + core->enable_count++; } - core->enable_count++; return 0; +err: + parent = core->parent; + list_for_each_entry_safe_continue(core, tmp, &head, enable_list) + list_del_init(&core->enable_list); + clk_core_disable(parent); + return ret; } static int clk_core_enable_lock(struct clk_core *core) @@ -3281,6 +3294,8 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw) core->num_parents = hw->init->num_parents; core->min_rate = 0; core->max_rate = ULONG_MAX; + INIT_LIST_HEAD(&core->prepare_list); + INIT_LIST_HEAD(&core->enable_list); hw->core = core; /* allocate local copy in case parent_names is __initdata */ -- 2.19.1.568.g152ad8e336-goog