From patchwork Wed May 7 14:37:17 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pawel Moll X-Patchwork-Id: 4128981 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 62CE19F334 for ; Wed, 7 May 2014 14:39:52 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7838620253 for ; Wed, 7 May 2014 14:39:51 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7DB7420251 for ; Wed, 7 May 2014 14:39:50 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Wi2yl-0006vE-Pc; Wed, 07 May 2014 14:37:51 +0000 Received: from fw-tnat.austin.arm.com ([217.140.110.23] helo=collaborate-mta1.arm.com) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Wi2yj-0006jS-AN for linux-arm-kernel@lists.infradead.org; Wed, 07 May 2014 14:37:49 +0000 Received: from [10.2.201.45] (hornet.cambridge.arm.com [10.2.201.45]) by collaborate-mta1.arm.com (Postfix) with ESMTP id CBED113F88D; Wed, 7 May 2014 09:37:15 -0500 (CDT) Message-ID: <1399473437.3706.25.camel@hornet> Subject: Re: [PATCH v2] of: Keep track of populated platform devices From: Pawel Moll To: Grant Likely Date: Wed, 07 May 2014 15:37:17 +0100 In-Reply-To: References: <1398858529.24255.3.camel@hornet> <1398866717-20268-1-git-send-email-pawel.moll@arm.com> <20140501092635.05011C409DA@trevor.secretlab.ca> X-Mailer: Evolution 3.10.4-0ubuntu1 Mime-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140507_073749_458710_9DE0FCDF X-CRM114-Status: GOOD ( 27.83 ) X-Spam-Score: -0.7 (/) Cc: "devicetree@vger.kernel.org" , Rob Herring , "linux-arm-kernel@lists.infradead.org" X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-2.5 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Thu, 2014-05-01 at 10:43 +0100, Grant Likely wrote: > > That doesn't work in the case where drivers use of_platform_populate(). > > MFD devices in particular make use of it. If the driver does not get > > cleared on removal of the devices, then all MFD users will be broken on > > driver unbind/rebind. * > > > > We really need to have the inverse of of_platform_populate which will > > remove all child and child's child devices and clear all flags and such. > > Right now moany drivers are open-coding the removal. Agreed, but, unless I'm missing some fundamental issue, I believe we can solve the flag clearing problem in a generic way: --8<----------- 8<----------- > static int __of_platform_unpopulate_device(struct device *dev, void *c) > { > if (!dev->of_node || !of_node_get_flag(dev->of_node, OF_POPULATED) > return 0; > > // recursively remove the children too --- I'd like to find a way > to do this non-recursively > device_for_each_child(dev, NULL, __of_platform_unpopulate_device); As of_platform_populate() is recursive itself, I don't see much problem with this. > // Need to check if the device should be explicitly unbound from > it's driver before removing it. However, I think the driver core takes > care of this for us. Yep, removing either a driver or a device unbinds all existing pairs. > // Remove based on the bus type > switch (dev->bus) { > case &platform_bus_type: To my surprise gcc said "error: pointers are not permitted as case values". One learns every day ;-) > platform_device_remove(to_platform_device(dev)); > break; > case &amba_bus_type: > amba_device_remove(to_platform_device(dev)); > break; > } > > // Should check here if there are any other children to the > device. It is probably bad to remove a device that still has children. > Need to check what the driver core will do. > } The reference count will be still be greater than 0, so the parent won't be harmed. Nevertheless it's better to consciously handle such case. At least I tried. Pawel Acked-by: Grant Likely diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index 3cf61a1..0f489fb 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -17,6 +17,7 @@ #include #include #include +#include #include @@ -268,6 +269,7 @@ static void amba_device_release(struct device *dev) { struct amba_device *d = to_amba_device(dev); + of_device_node_put(dev); if (d->res.parent) release_resource(&d->res); kfree(d); diff --git a/include/linux/of_device.h b/include/linux/of_device.h index ef37021..fd14d46 100644 --- a/include/linux/of_device.h +++ b/include/linux/of_device.h @@ -41,6 +41,8 @@ extern int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env static inline void of_device_node_put(struct device *dev) { + if (dev->of_node) + of_node_clear_flag(dev->of_node, OF_POPULATED); of_node_put(dev->of_node); } --8<----------- This will work even if one manually unregisters a DT-originating device, because of_device_node_put() would be called in both amba and platform device (kobj) release path. By the way, the fact that today amba_device_release() doesn't do of_device_node_put() seems like a bug to me? (node's reference counter won't be decremented) > The function shouldn't be too difficult. I would expect it to look > something like this. You'll need to check the details. 8<----------- diff --git a/drivers/of/platform.c b/drivers/of/platform.c index dd4328c..b6b5a2b 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -493,4 +493,49 @@ int of_platform_populate(struct device_node *root, return rc; } EXPORT_SYMBOL_GPL(of_platform_populate); + +static int of_platform_device_destroy(struct device *dev, void *data) +{ + int *parents_children_left = data; + int my_children_left = 0; + + /* Do not touch devices not populated from the device tree */ + if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED)) { + *parents_children_left++; + return 0; + } + + device_for_each_child(dev, &my_children_left, + of_platform_device_destroy); + if (my_children_left) { + *parents_children_left++; + return 0; + } + + if (dev->bus == &platform_bus_type) + platform_device_unregister(to_platform_device(dev)); + else if (dev->bus == &amba_bustype) + amba_device_unregister(to_amba_device(dev)); + + return 0; +} + +/** + * of_platform_depopulate() - Remove devices populated from device tree + * @parent: device which childred will be removed + * + * Complementary to of_platform_populate(), this function removes children + * of the given device (and, recurrently, their children) that have been + * created from their respective device tree nodes (and only those, + * leaving others - eg. manually created - unharmed). */ + */ +int of_platform_depopulate(struct device *parent) +{ + int children_left = 0; + + device_for_each_child(dev, &children_left, of_platform_device_destroy); + + return children_left ? -EBUSY : 0; +} +EXPORT_SYMBOL_GPL(of_platform_depopulate); #endif /* CONFIG_OF_ADDRESS */ diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h index 05cb4a9..ef4f4ad 100644 --- a/include/linux/of_platform.h +++ b/include/linux/of_platform.h @@ -72,6 +72,7 @@ extern int of_platform_populate(struct device_node *root, const struct of_device_id *matches, const struct of_dev_auxdata *lookup, struct device *parent); +static inline int of_platform_depopulate(struct device *parent); #else static inline int of_platform_populate(struct device_node *root, const struct of_device_id *matches, @@ -80,6 +81,10 @@ static inline int of_platform_populate(struct device_node *root, { return -ENODEV; } +static inline int of_platform_depopulate(struct device *parent) +{ + return -ENODEV; +} #endif #endif /* _LINUX_OF_PLATFORM_H */