From patchwork Fri May 15 05:34:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Saravana Kannan X-Patchwork-Id: 200510 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=-17.4 required=3.0 tests=DKIMWL_WL_MED, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable 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 BB6A2C433DF for ; Fri, 15 May 2020 05:35:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B971206F1 for ; Fri, 15 May 2020 05:35:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="X4Ednklj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726706AbgEOFfZ (ORCPT ); Fri, 15 May 2020 01:35:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726586AbgEOFfM (ORCPT ); Fri, 15 May 2020 01:35:12 -0400 Received: from mail-qv1-xf4a.google.com (mail-qv1-xf4a.google.com [IPv6:2607:f8b0:4864:20::f4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36D88C05BD0A for ; Thu, 14 May 2020 22:35:12 -0700 (PDT) Received: by mail-qv1-xf4a.google.com with SMTP id ce16so1480049qvb.15 for ; Thu, 14 May 2020 22:35:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=IWhO5anUDBUoeZ5ya2LJvLEB+Rih7YqmYbCBAkd+SfU=; b=X4EdnkljxZN1gGkqK79onM46/6Tljbkxek8tFeo4vdNLUR45GdlwewfukRIfu8g3q8 TIBGSWYxorYwfrON38B1GIuSb4UkF9ZDBXvoA+ri3xSzcrgEn5WxPa9NPTk3DmUoTuvq 1sOn5rFmlP9fDSbh/dJsXyJCEuLArRzQXJwLxZQKu+mBnjOhYjTT5X6CXh/xAprnl+tx fQEJ1SrydXkgB/CRKaVCyDBoErO7S1fvMtHG7fMdhyiAKffjMEiF1Uba3huXJTrKODzx mSPbHE0fslUYKNFDYZ1lhM07A5s/FFvRStTYSaMkiee4lw9rFYKFNrU1O/NKCizbccc7 RP8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=IWhO5anUDBUoeZ5ya2LJvLEB+Rih7YqmYbCBAkd+SfU=; b=sT1gEUZOUJF1a5psU4WqJjx5Xy9uBnkU/2e6PMPMf3hEjWQoBEEbuH7YAlEV1V5ojp BCC6ufYOOeBB+c+xY8wsrJ0jAcwAYrQTZYZcgf/YREzEq04jK9k1E1xTlJ+veX6JTApc apnSFt2IeKwL4LB0oz4Dsshzs42i8AxxiO8f6QldXOv40Pbk8vp/hFCIPjt8qil0R8bz 75eFemWZpOMbllscoisTJmmcFfotCTLCBe5Zx8OrkyhOPA0Y7ct/r7Z90ewZ2WN2VP3x z1a65vmNFarCMqINt4/tAqUcr6NMC7xYEGa95rgOD7ZsGNjHLIojNlL1EI8YppQlp78A HCMQ== X-Gm-Message-State: AOAM5330RLw9zF8RNsV0nIyAqU+YKY0yI5S9jxgdJhE7mfKXSnR1HLk2 2lX0uDhQqQnecdmdundhxf4TIkrirXXQZvk= X-Google-Smtp-Source: ABdhPJzf+yR6toilb6eZvzt8nUDldrlq3UvGr4np2ygHZkdy3MBL8xvEzwokJYuxVbKMuhtzbC8xDJ3p+xEBBx4= X-Received: by 2002:a0c:e744:: with SMTP id g4mr1872339qvn.55.1589520911303; Thu, 14 May 2020 22:35:11 -0700 (PDT) Date: Thu, 14 May 2020 22:34:59 -0700 In-Reply-To: <20200515053500.215929-1-saravanak@google.com> Message-Id: <20200515053500.215929-4-saravanak@google.com> Mime-Version: 1.0 References: <20200515053500.215929-1-saravanak@google.com> X-Mailer: git-send-email 2.26.2.761.g0e0b3e54be-goog Subject: [PATCH v1 3/4] driver core: fw_devlink: Add support for batching fwnode parsing From: Saravana Kannan To: Greg Kroah-Hartman , "Rafael J. Wysocki" , Rob Herring , Frank Rowand , Len Brown Cc: Saravana Kannan , kernel-team@android.com, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-acpi@vger.kernel.org, Ji Luo Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org The amount of time spent parsing fwnodes of devices can become really high if the devices are added in an non-ideal order. Worst case can be O(N^2) when N devices are added. But this can be optimized to O(N) by adding all the devices and then parsing all their fwnodes in one batch. This commit adds fw_devlink_pause() and fw_devlink_resume() to allow doing this. Signed-off-by: Saravana Kannan --- drivers/base/base.h | 1 + drivers/base/core.c | 116 ++++++++++++++++++++++++++++++++++++++--- drivers/base/dd.c | 8 +++ include/linux/fwnode.h | 2 + 4 files changed, 120 insertions(+), 7 deletions(-) diff --git a/drivers/base/base.h b/drivers/base/base.h index 40fb069a8a7e..95c22c0f9036 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -153,6 +153,7 @@ extern char *make_class_name(const char *name, struct kobject *kobj); extern int devres_release_all(struct device *dev); extern void device_block_probing(void); extern void device_unblock_probing(void); +extern void driver_deferred_probe_force_trigger(void); /* /sys/devices directory */ extern struct kset *devices_kset; diff --git a/drivers/base/core.c b/drivers/base/core.c index f585d92e09d0..84c569726d75 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -49,6 +49,9 @@ static LIST_HEAD(wait_for_suppliers); static DEFINE_MUTEX(wfs_lock); static LIST_HEAD(deferred_sync); static unsigned int defer_sync_state_count = 1; +static unsigned int defer_fw_devlink_count; +static DEFINE_MUTEX(defer_fw_devlink_lock); +static bool fw_devlink_is_permissive(void); #ifdef CONFIG_SRCU static DEFINE_MUTEX(device_links_lock); @@ -527,7 +530,7 @@ static void device_link_add_missing_supplier_links(void) int ret = fwnode_call_int_op(dev->fwnode, add_links, dev); if (!ret) list_del_init(&dev->links.needs_suppliers); - else if (ret != -ENODEV) + else if (ret != -ENODEV || fw_devlink_is_permissive()) dev->links.need_for_probe = false; } mutex_unlock(&wfs_lock); @@ -1177,17 +1180,116 @@ static void fw_devlink_link_device(struct device *dev) { int fw_ret; - device_link_add_missing_supplier_links(); + if (!fw_devlink_flags) + return; + + mutex_lock(&defer_fw_devlink_lock); + if (!defer_fw_devlink_count) + device_link_add_missing_supplier_links(); + + /* + * The device's fwnode not having add_links() doesn't affect if other + * consumers can find this device as a supplier. So, this check is + * intentionally placed after device_link_add_missing_supplier_links(). + */ + if (!fwnode_has_op(dev->fwnode, add_links)) + goto out; - if (fw_devlink_flags && fwnode_has_op(dev->fwnode, add_links)) { + /* + * If fw_devlink is being deferred, assume all devices have mandatory + * suppliers they need to link to later. Then, when the fw_devlink is + * resumed, all these devices will get a chance to try and link to any + * suppliers they have. + */ + if (!defer_fw_devlink_count) { fw_ret = fwnode_call_int_op(dev->fwnode, add_links, dev); - if (fw_ret == -ENODEV && !fw_devlink_is_permissive()) - device_link_wait_for_mandatory_supplier(dev); - else if (fw_ret) - device_link_wait_for_optional_supplier(dev); + if (fw_ret == -ENODEV && fw_devlink_is_permissive()) + fw_ret = -EAGAIN; + } else { + fw_ret = -ENODEV; } + + if (fw_ret == -ENODEV) + device_link_wait_for_mandatory_supplier(dev); + else if (fw_ret) + device_link_wait_for_optional_supplier(dev); + +out: + mutex_unlock(&defer_fw_devlink_lock); } +/** + * fw_devlink_pause - Pause parsing of fwnode to create device links + * + * Calling this function defers any fwnode parsing to create device links until + * fw_devlink_resume() is called. Both these functions are ref counted and the + * caller needs to match the calls. + * + * While fw_devlink is paused: + * - Any device that is added won't have its fwnode parsed to create device + * links. + * - The probe of the device will also be deferred during this period. + * - Any devices that were already added, but waiting for suppliers won't be + * able to link to newly added devices. + * + * Once fw_devlink_resume(): + * - All the fwnodes that was not parsed will be parsed. + * - All the devices that were deferred probing will be reattempted if they + * aren't waiting for any more suppliers. + * + * This pair of functions, is mainly meant to optimize the parsing of fwnodes + * when a lot of devices that need to link to each other are added in a short + * interval of time. For example, adding all the top level devices in a system. + * + * For example, if N devices are added and: + * - All the consumers are added before their suppliers + * - All the suppliers of the N devices are part of the N devices + * + * Then: + * + * - With the use of fw_devlink_pause() and fw_devlink_resume(), each device + * will only need one parsing of its fwnode because it is guaranteed to find + * all the supplier devices already registered and ready to link to. It won't + * have to do another pass later to find one or more suppliers it couldn't + * find in the first parse of the fwnode. So, we'll only need O(N) fwnode + * parses. + * + * - Without the use of fw_devlink_pause() and fw_devlink_resume(), we would + * end up doing O(N^2) parses of fwnodes because every device that's added is + * guaranteed to trigger a parse of the fwnode of every device added before + * it. This O(N^2) parse is made worse by the fact that when a fwnode of a + * device is parsed, all it descendant devices might need to have their + * fwnodes parsed too (even if the devices themselves aren't added). + */ +void fw_devlink_pause(void) +{ + mutex_lock(&defer_fw_devlink_lock); + defer_fw_devlink_count++; + mutex_unlock(&defer_fw_devlink_lock); +} + +/** fw_devlink_resume - Resume parsing of fwnode to create device links + * + * This function is used in conjunction with fw_devlink_pause() and is ref + * counted. See documentation for fw_devlink_pause() for more details. + */ +void fw_devlink_resume(void) +{ + mutex_lock(&defer_fw_devlink_lock); + if (!defer_fw_devlink_count) { + WARN(true, "Unmatched fw_devlink pause/resume!"); + goto out; + } + + defer_fw_devlink_count--; + if (defer_fw_devlink_count) + goto out; + + device_link_add_missing_supplier_links(); + driver_deferred_probe_force_trigger(); +out: + mutex_unlock(&defer_fw_devlink_lock); +} /* Device links support end. */ int (*platform_notify)(struct device *dev) = NULL; diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 48ca81cb8ebc..63991d97adcc 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -160,6 +160,14 @@ static bool driver_deferred_probe_enable = false; * again. */ static void driver_deferred_probe_trigger(void) +{ + if (!driver_deferred_probe_enable) + return; + + driver_deferred_probe_force_trigger(); +} + +void driver_deferred_probe_force_trigger(void) { if (!driver_deferred_probe_enable) return; diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h index e0abafbb17f8..9506f8ec0974 100644 --- a/include/linux/fwnode.h +++ b/include/linux/fwnode.h @@ -171,5 +171,7 @@ struct fwnode_operations { #define get_dev_from_fwnode(fwnode) get_device((fwnode)->dev) extern u32 fw_devlink_get_flags(void); +void fw_devlink_pause(void); +void fw_devlink_resume(void); #endif