From patchwork Sat Mar 25 19:42:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 74978 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b0ea:0:b0:3b6:4342:cba0 with SMTP id b10csp584005vqo; Sat, 25 Mar 2023 13:00:59 -0700 (PDT) X-Google-Smtp-Source: AKy350ZpIW9ALZGJlJzHq3s/iLODLEV1puHHUFwY+0XKDa+6tVIVoNrlJsgsBJOHeFmRTwDQBKnH X-Received: by 2002:a17:90b:4b87:b0:23d:1e5f:eea6 with SMTP id lr7-20020a17090b4b8700b0023d1e5feea6mr7622841pjb.24.1679774459060; Sat, 25 Mar 2023 13:00:59 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1679774459; cv=none; d=google.com; s=arc-20160816; b=LN+liDtqzX4DlVONKPZLa/n2yiXAuZp26BRAxxjUuG1PF3ew2gQqjnFhWl64GeFAxi eGy/BlEbetiqAE0IThKs+lIpdqKwK2oPALY3tbcg4IFR18G8KLv2TH3RhWajw3V7V0kw 5RNo3kOxdLWxbxGOOEBRIEQ45+9tzJ2o15xuDlhB8x8JIkTZjYFhuXFa2DCXonjOPCMW hbcJbS3rl0MzeyjswE/LQFILsDuWo8DxUTJyHhYnrKZ85AEajr4bMPaEK5KLkoK8NZue qUZedtk62wLZosn2T/6cW/lehBbB7lsw90od0GRY8AfD7bG0d+BDsVcx/e7u4YCNyevq Z0oA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from:dkim-signature; bh=NznvKqcqV64HsOIy7lOLHrjumvPZ4qVENw+5ZtNQSA8=; b=lr/vsdAEELOg7vsunuWDaavtZnLmgAwVQcSlh+pSBBN9dWcRf//dB+tVXUFDUtTGsT wfG/Nr7bjVEfKOqdTDVSCbhL/ytkMCOkv9oA6Dj3vohEUvblzqQpPWhvcegmK2qzVxb2 edfo9SKasMcaJQ8Uizrak4iCMHT5vaE62DcCPjZ8L0DdgzhwQDA4EejKZWnid0tNKPHi +AToPOVTohQdObIDKRO+obrG4J1PepcEBSVcVC13X2Xhky0V0MtOxb3G6oq9VHEy9jNx 5kf6fBP8AQcwHsNBlQDigWNdMC2zDZMFEGvEg7A5WxOZ8NIMB4GJJcCLCqav7sIpHAhz xGbw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=QYLEoKif; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id h34-20020a635762000000b004fbd58ce355si23237532pgm.511.2023.03.25.13.00.45; Sat, 25 Mar 2023 13:00:59 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=QYLEoKif; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231823AbjCYTmq (ORCPT + 99 others); Sat, 25 Mar 2023 15:42:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52176 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230118AbjCYTmo (ORCPT ); Sat, 25 Mar 2023 15:42:44 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C6A2D335 for ; Sat, 25 Mar 2023 12:42:43 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D979A60C7B for ; Sat, 25 Mar 2023 19:42:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5474C433D2; Sat, 25 Mar 2023 19:42:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1679773362; bh=JcCdF0mN69Zz2znnMJC1O/kdnaIN+fa7+l2p4uMQljM=; h=From:To:Cc:Subject:Date:From; b=QYLEoKifZabVQouyjO7eTab2mJqL+2+L5Cnk4/3WVOtBmdUA8ogzgkXSVmTkJiBXu gy1Jnwfjdy8YU6X3yhKgaZYGLinwLmScVy+i9C3Tt2FxVQp21Hmcw7bq5fuwl0ky67 8Iqqw18c/UD8In9mOQKY+oNQ4FtJ24CxiG93+r80= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" Subject: [PATCH 1/2] driver core: class: implement class_get/put without the private pointer. Date: Sat, 25 Mar 2023 20:42:33 +0100 Message-Id: <20230325194234.46588-1-gregkh@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4281; i=gregkh@linuxfoundation.org; h=from:subject; bh=JcCdF0mN69Zz2znnMJC1O/kdnaIN+fa7+l2p4uMQljM=; b=owGbwMvMwCRo6H6F97bub03G02pJDCnyfiuunjoWeMJVebvihnPhZ+/VbP2+p7307qkNi31fb CmQ//KXtSOWhUGQiUFWTJHlyzaeo/srDil6GdqehpnDygQyhIGLUwAmMr+HYcHOQvltjw1nmJ5N 2n47TtP7m7Ln+mCGBVPvPCstYlZutoy4LFiwxdnfoImlGgA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 X-Spam-Status: No, score=-5.2 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI,SPF_HELO_NONE, SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1761371183257994820?= X-GMAIL-MSGID: =?utf-8?q?1761371183257994820?= Much like what was done in commit 273afac615ad ("driver core: bus: implement bus_get/put() without the private pointer"), it is time to move the driver core away from using the internal private pointer in struct class in order to enable it to be always a constant and be placed in read-only memory in the future. First step in doing this is to create a helper function that turns a 'struct class' into 'struct subsys_private' called class_to_subsys(). class_to_subsys() walks the list of registered busses in the system and finds the matching one based on the pointer to the class itself. As this is a short list, and this function is not on any fast path, it should not be noticable. Implement class_get() and class_put() using this new helper function. Cc: "Rafael J. Wysocki" Signed-off-by: Greg Kroah-Hartman --- drivers/base/class.c | 81 ++++++++++++++++++++++++++++++++++---------- 1 file changed, 63 insertions(+), 18 deletions(-) diff --git a/drivers/base/class.c b/drivers/base/class.c index ecbf8b5b0dff..90678f6ed4ba 100644 --- a/drivers/base/class.c +++ b/drivers/base/class.c @@ -20,8 +20,70 @@ #include #include "base.h" +/* /sys/class */ +static struct kset *class_kset; + #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr) +/** + * class_to_subsys - Turn a struct class into a struct subsys_private + * + * @class: pointer to the struct bus_type to look up + * + * The driver core internals need to work on the subsys_private structure, not + * the external struct class pointer. This function walks the list of + * registered classes in the system and finds the matching one and returns the + * internal struct subsys_private that relates to that class. + * + * Note, the reference count of the return value is INCREMENTED if it is not + * NULL. A call to subsys_put() must be done when finished with the pointer in + * order for it to be properly freed. + */ +static struct subsys_private *class_to_subsys(const struct class *class) +{ + struct subsys_private *sp = NULL; + struct kobject *kobj; + + if (!class || !class_kset) + return NULL; + + spin_lock(&class_kset->list_lock); + + if (list_empty(&class_kset->list)) + goto done; + + list_for_each_entry(kobj, &class_kset->list, entry) { + struct kset *kset = container_of(kobj, struct kset, kobj); + + sp = container_of_const(kset, struct subsys_private, subsys); + if (sp->class == class) + goto done; + } + sp = NULL; +done: + sp = subsys_get(sp); + spin_unlock(&class_kset->list_lock); + return sp; +} + +static const struct class *class_get(const struct class *class) +{ + struct subsys_private *sp = class_to_subsys(class); + + if (sp) + return class; + return NULL; +} + +static void class_put(const struct class *class) +{ + struct subsys_private *sp = class_to_subsys(class); + + /* two puts are required as the call to bus_to_subsys incremented it again */ + subsys_put(sp); + subsys_put(sp); +} + static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr, char *buf) { @@ -83,10 +145,6 @@ static const struct kobj_type class_ktype = { .child_ns_type = class_child_ns_type, }; -/* Hotplug events for classes go to the class subsys */ -static struct kset *class_kset; - - int class_create_file_ns(const struct class *cls, const struct class_attribute *attr, const void *ns) { @@ -109,19 +167,6 @@ void class_remove_file_ns(const struct class *cls, const struct class_attribute } EXPORT_SYMBOL_GPL(class_remove_file_ns); -static struct class *class_get(struct class *cls) -{ - if (cls) - kset_get(&cls->p->subsys); - return cls; -} - -static void class_put(struct class *cls) -{ - if (cls) - kset_put(&cls->p->subsys); -} - static struct device *klist_class_to_dev(struct klist_node *n) { struct device_private *p = to_device_private_class(n); @@ -435,7 +480,7 @@ EXPORT_SYMBOL_GPL(class_find_device); int class_interface_register(struct class_interface *class_intf) { - struct class *parent; + const struct class *parent; struct class_dev_iter iter; struct device *dev; From patchwork Sat Mar 25 19:42:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 74980 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b0ea:0:b0:3b6:4342:cba0 with SMTP id b10csp591211vqo; Sat, 25 Mar 2023 13:18:32 -0700 (PDT) X-Google-Smtp-Source: AKy350aUcqb7VdXMyIH/6QFDDBisJfBc1k5c8bdh/MrwPFPLxseRhSNXQ+00WNkTBrJlp19FRrNP X-Received: by 2002:a17:906:a3ca:b0:926:e917:133c with SMTP id ca10-20020a170906a3ca00b00926e917133cmr6924661ejb.47.1679775512417; Sat, 25 Mar 2023 13:18:32 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1679775512; cv=none; d=google.com; s=arc-20160816; b=O938RptysvWcC1fKDhtClpQdfxSWE6zZuOijseptPIK/MR3r/Lkw0+MB7EgJJQ7pnv uIGQxT/r3IHd7JHQYCN8LwjWCJ9cj4mkFDMiOCMAumxp9L5tcxwEzIRQRQs0CzYciaoo W8zpzMnFvX6vmRi1SlyTy/NcTa9Wb8IuiyzL1x0gA6IZpSfhuhoyp5/INp3lcjWo8agW 1glar6C12M5OwpZZLfCYVqIc/bAuLtrUp6d2Ghp9q0onE+GYQGhQdyLomY1P/9ETG/o4 2f+LyXyGUfridFJfsr2zb4emrC3kRQ0iFf1vBLntBwku99hPL7tToLx/CJ4L0XpemdXs fw0Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=6DuMZesYLMt5cuTesaAzSAy8L3K5fV8KpOv/kpZIR5M=; b=kYNJMA0k3+dIlY/63TIyfbfCiuySEGYwf9guyXtea/U2xFAMYsp9cDeHpFy7SsBCeE /HDq/Bop0afRMzWGRqoNXo420lH0UBdsaBdrR0OecGrHyGheK1whZqnsOmwzZBR4DLL7 QohUQ61PiwtwHHbw+8xdBycpwJV0DocCbquUKL0rRhs2zKRO8OwK1RIW8TwhIRonW4M2 t1jeJhkJbMG5ncTr5ZSDHNgUSatwuWIFNSpL6wv3GXzG3i8KGYQ7PoLqHVD91cyqAn0C 3gTHw4SjQKRv3seRKcTAynyh6pV1Gg7g5QpCA83u8gOW/qDsxkBgSCrYPni1UeAhkTBc OCeA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=JzO1eCyM; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: from out1.vger.email (out1.vger.email. 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Wysocki" Subject: [PATCH 2/2] driver core: class.c: convert to only use class_to_subsys Date: Sat, 25 Mar 2023 20:42:34 +0100 Message-Id: <20230325194234.46588-2-gregkh@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230325194234.46588-1-gregkh@linuxfoundation.org> References: <20230325194234.46588-1-gregkh@linuxfoundation.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=8213; i=gregkh@linuxfoundation.org; h=from:subject; bh=LMJaj8fZccWYkSYxa6ua+HxKjVQ+2DSpF22IjtslcZU=; b=owGbwMvMwCRo6H6F97bub03G02pJDCnyfqu2fjVwi1o2rXXB6eaQJNnLOTumZWxVVqjmkIpY9 /RO3GeLjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZjI5g8Mc7hOOUq8cLj1S4Lz ZmV5xT6za9ZfWxjmKWqkqt9/udAjdD7r3MisBUtuzqv7CAA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 X-Spam-Status: No, score=-2.5 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1761372287478284437?= X-GMAIL-MSGID: =?utf-8?q?1761372287478284437?= Now that class_to_subsys() can be used to get access to the internal class private pointer, convert the remaining few places in class.c that were accessing the pointer directly to use class_to_subsys() instead. By doing this, the need for class_get() and class_put() goes away as no one actually tries to increment the class structures anymore, only the internal dynamic one. Cc: "Rafael J. Wysocki" Signed-off-by: Greg Kroah-Hartman --- drivers/base/class.c | 113 +++++++++++++++++++++++-------------------- 1 file changed, 61 insertions(+), 52 deletions(-) diff --git a/drivers/base/class.c b/drivers/base/class.c index 90678f6ed4ba..45d66a4fb375 100644 --- a/drivers/base/class.c +++ b/drivers/base/class.c @@ -66,24 +66,6 @@ static struct subsys_private *class_to_subsys(const struct class *class) return sp; } -static const struct class *class_get(const struct class *class) -{ - struct subsys_private *sp = class_to_subsys(class); - - if (sp) - return class; - return NULL; -} - -static void class_put(const struct class *class) -{ - struct subsys_private *sp = class_to_subsys(class); - - /* two puts are required as the call to bus_to_subsys incremented it again */ - subsys_put(sp); - subsys_put(sp); -} - static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr, char *buf) { @@ -148,13 +130,15 @@ static const struct kobj_type class_ktype = { int class_create_file_ns(const struct class *cls, const struct class_attribute *attr, const void *ns) { + struct subsys_private *sp = class_to_subsys(cls); int error; - if (cls) - error = sysfs_create_file_ns(&cls->p->subsys.kobj, - &attr->attr, ns); - else - error = -EINVAL; + if (!sp) + return -EINVAL; + + error = sysfs_create_file_ns(&sp->subsys.kobj, &attr->attr, ns); + subsys_put(sp); + return error; } EXPORT_SYMBOL_GPL(class_create_file_ns); @@ -162,8 +146,13 @@ EXPORT_SYMBOL_GPL(class_create_file_ns); void class_remove_file_ns(const struct class *cls, const struct class_attribute *attr, const void *ns) { - if (cls) - sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns); + struct subsys_private *sp = class_to_subsys(cls); + + if (!sp) + return; + + sysfs_remove_file_ns(&sp->subsys.kobj, &attr->attr, ns); + subsys_put(sp); } EXPORT_SYMBOL_GPL(class_remove_file_ns); @@ -187,18 +176,6 @@ static void klist_class_dev_put(struct klist_node *n) put_device(dev); } -static int class_add_groups(const struct class *cls, - const struct attribute_group **groups) -{ - return sysfs_create_groups(&cls->p->subsys.kobj, groups); -} - -static void class_remove_groups(const struct class *cls, - const struct attribute_group **groups) -{ - return sysfs_remove_groups(&cls->p->subsys.kobj, groups); -} - int class_register(struct class *cls) { struct subsys_private *cp; @@ -235,8 +212,7 @@ int class_register(struct class *cls) if (error) goto err_out; - error = class_add_groups(class_get(cls), cls->class_groups); - class_put(cls); + error = sysfs_create_groups(&cp->subsys.kobj, cls->class_groups); if (error) { kobject_del(&cp->subsys.kobj); kfree_const(cp->subsys.kobj.name); @@ -253,9 +229,16 @@ EXPORT_SYMBOL_GPL(class_register); void class_unregister(const struct class *cls) { + struct subsys_private *sp = class_to_subsys(cls); + + if (!sp) + return; + pr_debug("device class '%s': unregistering\n", cls->name); - class_remove_groups(cls, cls->class_groups); - kset_unregister(&cls->p->subsys); + + sysfs_remove_groups(&sp->subsys.kobj, cls->class_groups); + kset_unregister(&sp->subsys); + subsys_put(sp); } EXPORT_SYMBOL_GPL(class_unregister); @@ -335,11 +318,15 @@ EXPORT_SYMBOL_GPL(class_destroy); void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class, const struct device *start, const struct device_type *type) { + struct subsys_private *sp = class_to_subsys(class); struct klist_node *start_knode = NULL; + if (!sp) + return; + if (start) start_knode = &start->p->knode_class; - klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode); + klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode); iter->type = type; } EXPORT_SYMBOL_GPL(class_dev_iter_init); @@ -406,13 +393,14 @@ EXPORT_SYMBOL_GPL(class_dev_iter_exit); int class_for_each_device(const struct class *class, const struct device *start, void *data, int (*fn)(struct device *, void *)) { + struct subsys_private *sp = class_to_subsys(class); struct class_dev_iter iter; struct device *dev; int error = 0; if (!class) return -EINVAL; - if (!class->p) { + if (!sp) { WARN(1, "%s called for class '%s' before it was initialized", __func__, class->name); return -EINVAL; @@ -425,6 +413,7 @@ int class_for_each_device(const struct class *class, const struct device *start, break; } class_dev_iter_exit(&iter); + subsys_put(sp); return error; } @@ -454,12 +443,13 @@ struct device *class_find_device(const struct class *class, const struct device const void *data, int (*match)(struct device *, const void *)) { + struct subsys_private *sp = class_to_subsys(class); struct class_dev_iter iter; struct device *dev; if (!class) return NULL; - if (!class->p) { + if (!sp) { WARN(1, "%s called for class '%s' before it was initialized", __func__, class->name); return NULL; @@ -473,6 +463,7 @@ struct device *class_find_device(const struct class *class, const struct device } } class_dev_iter_exit(&iter); + subsys_put(sp); return dev; } @@ -480,6 +471,7 @@ EXPORT_SYMBOL_GPL(class_find_device); int class_interface_register(struct class_interface *class_intf) { + struct subsys_private *sp; const struct class *parent; struct class_dev_iter iter; struct device *dev; @@ -487,19 +479,25 @@ int class_interface_register(struct class_interface *class_intf) if (!class_intf || !class_intf->class) return -ENODEV; - parent = class_get(class_intf->class); - if (!parent) + parent = class_intf->class; + sp = class_to_subsys(parent); + if (!sp) return -EINVAL; - mutex_lock(&parent->p->mutex); - list_add_tail(&class_intf->node, &parent->p->interfaces); + /* + * Reference in sp is now incremented and will be dropped when + * the interface is removed in the call to class_interface_unregister() + */ + + mutex_lock(&sp->mutex); + list_add_tail(&class_intf->node, &sp->interfaces); if (class_intf->add_dev) { class_dev_iter_init(&iter, parent, NULL, NULL); while ((dev = class_dev_iter_next(&iter))) class_intf->add_dev(dev, class_intf); class_dev_iter_exit(&iter); } - mutex_unlock(&parent->p->mutex); + mutex_unlock(&sp->mutex); return 0; } @@ -507,6 +505,7 @@ EXPORT_SYMBOL_GPL(class_interface_register); void class_interface_unregister(struct class_interface *class_intf) { + struct subsys_private *sp; struct class *parent = class_intf->class; struct class_dev_iter iter; struct device *dev; @@ -514,7 +513,11 @@ void class_interface_unregister(struct class_interface *class_intf) if (!parent) return; - mutex_lock(&parent->p->mutex); + sp = class_to_subsys(parent); + if (!sp) + return; + + mutex_lock(&sp->mutex); list_del_init(&class_intf->node); if (class_intf->remove_dev) { class_dev_iter_init(&iter, parent, NULL, NULL); @@ -522,9 +525,15 @@ void class_interface_unregister(struct class_interface *class_intf) class_intf->remove_dev(dev, class_intf); class_dev_iter_exit(&iter); } - mutex_unlock(&parent->p->mutex); + mutex_unlock(&sp->mutex); - class_put(parent); + /* + * Decrement the reference count twice, once for the class_to_subsys() + * call in the start of this function, and the second one from the + * reference increment in class_interface_register() + */ + subsys_put(sp); + subsys_put(sp); } EXPORT_SYMBOL_GPL(class_interface_unregister);