From nobody Tue Dec 16 16:35:29 2025 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 6FEC7C4167B for ; Thu, 30 Nov 2023 17:41:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346602AbjK3Rla (ORCPT ); Thu, 30 Nov 2023 12:41:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230460AbjK3Rl0 (ORCPT ); Thu, 30 Nov 2023 12:41:26 -0500 Received: from relay8-d.mail.gandi.net (relay8-d.mail.gandi.net [217.70.183.201]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 505A410D9; Thu, 30 Nov 2023 09:41:32 -0800 (PST) Received: by mail.gandi.net (Postfix) with ESMTPA id 5795A1BF205; Thu, 30 Nov 2023 17:41:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1701366091; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=bZYcrZj6HAsVu5Q51awnJk6PzzvhbxN5gePC1mvCY2w=; b=GjgAzYp+S5WY4+3ceyC2RNJMwmWxIw618L4lY8z8QTqOz9pD+uZ9aBpDPoBrsdcvOU0m5J w//JloZuZgvptd8q9Rr6X91vCPGpNBAVxv0X2u2xu8ZWQVJFYQwCkn3S1m7qdInJ0RDfyI jnyLEaj+D6v1EWYM1t7n8AObgK368bdS/ErOiT0v7bGoS0SIo9+FT10iMb1CBBPjPCVmnh 7BNHoQK8ZHR7u1Y5v6QJIpJ68zX2CdEkBnuiF7o/heEgFwEoVvNKzLnu1FAK0bWdhuvcaq htqaaHjA7C7aPSabvrm0+GJWUl4t3uJxGXvs0S7AQBHHHA5YEVhR2Rr+pKqH+g== From: Herve Codina To: Greg Kroah-Hartman , "Rafael J. Wysocki" , Rob Herring , Frank Rowand Cc: Lizhi Hou , Max Zhen , Sonal Santan , Stefano Stabellini , Jonathan Cameron , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Allan Nielsen , Horatiu Vultur , Steen Hegelund , Thomas Petazzoni , Herve Codina Subject: [PATCH 1/2] driver core: Introduce device_link_wait_removal() Date: Thu, 30 Nov 2023 18:41:08 +0100 Message-ID: <20231130174126.688486-2-herve.codina@bootlin.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231130174126.688486-1-herve.codina@bootlin.com> References: <20231130174126.688486-1-herve.codina@bootlin.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-GND-Sasl: herve.codina@bootlin.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The commit 80dd33cf72d1 ("drivers: base: Fix device link removal") introduces a workqueue to release the consumer and supplier devices used in the devlink. In the job queued, devices are release and in turn, when all the references to these devices are dropped, the release function of the device itself is called. Nothing is present to provide some synchronisation with this workqueue in order to ensure that all ongoing releasing operations are done and so, some other operations can be started safely. For instance, in the following sequence: 1) of_platform_depopulate() 2) of_overlay_remove() During the step 1, devices are released and related devlinks are removed (jobs pushed in the workqueue). During the step 2, OF nodes are destroyed but, without any synchronisation with devlink removal jobs, of_overlay_remove() can raise warnings related to missing of_node_put(): ERROR: memory leak, expected refcount 1 instead of 2 Indeed, the missing of_node_put() call is going to be done, too late, from the workqueue job execution. Introduce device_link_wait_removal() to offer a way to synchronize operations waiting for the end of devlink removals (i.e. end of workqueue jobs). Also, as a flushing operation is done on the workqueue, the workqueue used is moved from a system-wide workqueue to a local one. Signed-off-by: Herve Codina --- drivers/base/core.c | 26 +++++++++++++++++++++++--- include/linux/device.h | 1 + 2 files changed, 24 insertions(+), 3 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index ac026187ac6a..2e102a77758c 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -44,6 +44,7 @@ static bool fw_devlink_is_permissive(void); static void __fw_devlink_link_to_consumers(struct device *dev); static bool fw_devlink_drv_reg_done; static bool fw_devlink_best_effort; +static struct workqueue_struct *fw_devlink_wq; =20 /** * __fwnode_link_add - Create a link between two fwnode_handles. @@ -530,12 +531,26 @@ static void devlink_dev_release(struct device *dev) /* * It may take a while to complete this work because of the SRCU * synchronization in device_link_release_fn() and if the consumer or - * supplier devices get deleted when it runs, so put it into the "long" - * workqueue. + * supplier devices get deleted when it runs, so put it into the + * dedicated workqueue. */ - queue_work(system_long_wq, &link->rm_work); + queue_work(fw_devlink_wq, &link->rm_work); } =20 +/** + * device_link_wait_removal - Wait for ongoing devlink removal jobs to ter= minate + */ +void device_link_wait_removal(void) +{ + /* + * devlink removal jobs are queued in the dedicated work queue. + * To be sure that all removal jobs are terminated, ensure that any + * scheduled work has run to completion. + */ + drain_workqueue(fw_devlink_wq); +} +EXPORT_SYMBOL_GPL(device_link_wait_removal); + static struct class devlink_class =3D { .name =3D "devlink", .dev_groups =3D devlink_groups, @@ -4085,9 +4100,14 @@ int __init devices_init(void) sysfs_dev_char_kobj =3D kobject_create_and_add("char", dev_kobj); if (!sysfs_dev_char_kobj) goto char_kobj_err; + fw_devlink_wq =3D alloc_workqueue("fw_devlink_wq", 0, 0); + if (!fw_devlink_wq) + goto wq_err; =20 return 0; =20 + wq_err: + kobject_put(sysfs_dev_char_kobj); char_kobj_err: kobject_put(sysfs_dev_block_kobj); block_kobj_err: diff --git a/include/linux/device.h b/include/linux/device.h index 2b093e62907a..c26f4b3df2bd 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -1250,6 +1250,7 @@ void device_link_del(struct device_link *link); void device_link_remove(void *consumer, struct device *supplier); void device_links_supplier_sync_state_pause(void); void device_links_supplier_sync_state_resume(void); +void device_link_wait_removal(void); =20 /* Create alias, so I can be autoloaded. */ #define MODULE_ALIAS_CHARDEV(major,minor) \ --=20 2.42.0 From nobody Tue Dec 16 16:35:29 2025 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 E5B30C4167B for ; Thu, 30 Nov 2023 17:41:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346607AbjK3Rld (ORCPT ); Thu, 30 Nov 2023 12:41:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346496AbjK3Rl1 (ORCPT ); Thu, 30 Nov 2023 12:41:27 -0500 Received: from relay8-d.mail.gandi.net (relay8-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::228]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 363A810DE; Thu, 30 Nov 2023 09:41:33 -0800 (PST) Received: by mail.gandi.net (Postfix) with ESMTPA id 32A621BF206; Thu, 30 Nov 2023 17:41:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1701366091; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YCtXOEjZA4vVhqRvZxyqSJ/sJ1S1+pskPHyTx+aj7Bo=; b=LPx1+fRXYo9UizKn96Mo1PH2HBts4hfEy67nbnAsjK2WsGwfe2AqQ1twJi1tJiOE5RZ4C5 gaSWtIScGmcLpC8O+IbgeysUdhiqvbpILR9O1//gEskk4TKHXqDP1FCYd4nJdPuRyRyAgd NSVPU2xlfSCr3WLH1Xe0uUpzvCsH6XGMUxrtfyFn/UgZniaRrDzf1gGBOCJ0OMVPehGvhO pNJAlvN8ZOLQTzremWQjjtGbH7eTtKiUNV7heBDwknRhEZfXR1k7aVESlwktB7HsdUyVFk S449nqA/ggrQQOzKd5s5rvetaK5RNG58hVkjC0PxrrJdkTx03lxYC7XAzgweNw== From: Herve Codina To: Greg Kroah-Hartman , "Rafael J. Wysocki" , Rob Herring , Frank Rowand Cc: Lizhi Hou , Max Zhen , Sonal Santan , Stefano Stabellini , Jonathan Cameron , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Allan Nielsen , Horatiu Vultur , Steen Hegelund , Thomas Petazzoni , Herve Codina Subject: [PATCH 2/2] of: overlay: Synchronize of_overlay_remove() with the devlink removals Date: Thu, 30 Nov 2023 18:41:09 +0100 Message-ID: <20231130174126.688486-3-herve.codina@bootlin.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231130174126.688486-1-herve.codina@bootlin.com> References: <20231130174126.688486-1-herve.codina@bootlin.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-GND-Sasl: herve.codina@bootlin.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" In the following sequence: 1) of_platform_depopulate() 2) of_overlay_remove() During the step 1, devices are destroyed and devlinks are removed. During the step 2, OF nodes are destroyed but __of_changeset_entry_destroy() can raise warnings related to missing of_node_put(): ERROR: memory leak, expected refcount 1 instead of 2 ... Indeed, during the devlink removals performed at step 1, the removal itself releasing the device (and the attached of_node) is done by a job queued in a workqueue and so, it is done asynchronously with respect to function calls. When the warning is present, of_node_put() will be called but wrongly too late from the workqueue job. In order to be sure that any ongoing devlink removals are done before the of_node destruction, synchronize the of_overlay_remove() with the devlink removals. Signed-off-by: Herve Codina --- drivers/of/overlay.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c index a9a292d6d59b..5c5f808b163e 100644 --- a/drivers/of/overlay.c +++ b/drivers/of/overlay.c @@ -1202,6 +1202,12 @@ int of_overlay_remove(int *ovcs_id) goto out; } =20 + /* + * Wait for any ongoing device link removals before removing some of + * nodes + */ + device_link_wait_removal(); + mutex_lock(&of_mutex); =20 ovcs =3D idr_find(&ovcs_idr, *ovcs_id); --=20 2.42.0