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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY 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 9FAC4C28CC0 for ; Thu, 30 May 2019 07:31:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A34D25534 for ; Thu, 30 May 2019 07:31:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726326AbfE3Hbu (ORCPT ); Thu, 30 May 2019 03:31:50 -0400 Received: from mailgw02.mediatek.com ([1.203.163.81]:5027 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726027AbfE3Hbu (ORCPT ); Thu, 30 May 2019 03:31:50 -0400 X-UUID: b68e1545f7d44cc9bb1f86ad0f0b3d3b-20190530 X-UUID: b68e1545f7d44cc9bb1f86ad0f0b3d3b-20190530 Received: from mtkcas34.mediatek.inc [(172.27.4.253)] by mailgw02.mediatek.com (envelope-from ) (mailgw01.mediatek.com ESMTP with TLS) with ESMTP id 1253275830; Thu, 30 May 2019 15:31:40 +0800 Received: from MTKCAS36.mediatek.inc (172.27.4.186) by MTKMBS31N1.mediatek.inc (172.27.4.69) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Thu, 30 May 2019 15:31:39 +0800 Received: from [10.17.3.153] (172.27.4.253) by MTKCAS36.mediatek.inc (172.27.4.170) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Thu, 30 May 2019 15:31:39 +0800 Message-ID: <1559201499.8487.40.camel@mhfsdcap03> Subject: Re: [v3 PATCH] usb: create usb_debug_root for gadget only From: Chunfeng Yun To: Felipe Balbi CC: Greg Kroah-Hartman , Matthias Brugger , Randy Dunlap , , , , Date: Thu, 30 May 2019 15:31:39 +0800 In-Reply-To: <87k1ebj8vt.fsf@linux.intel.com> References: <87k1ebj8vt.fsf@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-MTK: N Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Hi Felipe, On Tue, 2019-05-28 at 11:11 +0300, Felipe Balbi wrote: > Hi, > > Chunfeng Yun writes: > > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c > > index 7fcb9f782931..88b3ee03a12d 100644 > > --- a/drivers/usb/core/usb.c > > +++ b/drivers/usb/core/usb.c > > @@ -1190,7 +1190,7 @@ EXPORT_SYMBOL_GPL(usb_debug_root); > > > > static void usb_debugfs_init(void) > > { > > - usb_debug_root = debugfs_create_dir("usb", NULL); > > + usb_debug_root = debugfs_create_dir(USB_DEBUG_ROOT_NAME, NULL); > > debugfs_create_file("devices", 0444, usb_debug_root, NULL, > > &usbfs_devices_fops); > > } > > might be a better idea to move this to usb common. Then have a function > which can be called by both host and gadget to maybe create the > directory: > > static struct dentry *usb_debug_root; > > struct dentry *usb_debugfs_init(void) > { > if (!usb_debug_root) > usb_debug_root = debugfs_create_dir("usb", NULL); > > return usb_debug_root; > } > > > Then usb core would be updated to something like: > > static void usb_core_debugfs_init(void) > { > struct dentry *root = usb_debugfs_init(); > > debugfs_create_file("devices", 0444, root, NULL, &usbfs_devices_fops); > } > I find a problem when move usb_debugfs_init() and usb_debugfs_cleanup() into usb common, it's easy to create "usb" directory, but difficult to cleanup it: common/common.c struct dentry *usb_debugfs_init(void) { if (!usb_debug_root) usb_debug_root = debugfs_create_dir("usb", NULL); return usb_debug_root; } void usb_debugfs_cleanup(void) { debugfs_remove_recursive(usb_debug_root); usb_debug_root = NULL; } core/usb.c static void usb_core_debugfs_init(void) { struct dentry *root = usb_debugfs_init(); debugfs_create_file("devices", 0444, root, NULL, &usbfs_devices_fops); } static int __init usb_init(void) { ... usb_core_debugfs_init(); ... } static void __exit usb_exit(void) { ... usb_debugfs_cleanup(); // will be error, gadget may use it. ... } gadget/udc/core.c static int __init usb_udc_init(void) { ... usb_debugfs_init(); ... } static void __exit usb_udc_exit(void) { ... usb_debugfs_cleanup(); // can't cleanup in fact, usb core may use it. } How to handle this case? introduce a reference count? do you have any suggestion? Thanks a lot