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, URIBL_BLOCKED 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 A19C2C282CE for ; Tue, 4 Jun 2019 06:44:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7B77424BA4 for ; Tue, 4 Jun 2019 06:44:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726683AbfFDGo1 (ORCPT ); Tue, 4 Jun 2019 02:44:27 -0400 Received: from mailgw02.mediatek.com ([1.203.163.81]:1863 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726410AbfFDGo0 (ORCPT ); Tue, 4 Jun 2019 02:44:26 -0400 X-UUID: 2147b8c1ae644262ad21e1bc246d6d60-20190604 X-UUID: 2147b8c1ae644262ad21e1bc246d6d60-20190604 Received: from mtkcas34.mediatek.inc [(172.27.4.253)] by mailgw02.mediatek.com (envelope-from ) (mailgw01.mediatek.com ESMTP with TLS) with ESMTP id 1706568245; Tue, 04 Jun 2019 14:44:20 +0800 Received: from MTKCAS32.mediatek.inc (172.27.4.184) by MTKMBS33DR.mediatek.inc (172.27.6.106) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Tue, 4 Jun 2019 14:44:18 +0800 Received: from [10.17.3.153] (172.27.4.253) by MTKCAS32.mediatek.inc (172.27.4.170) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Tue, 4 Jun 2019 14:44:18 +0800 Message-ID: <1559630658.8487.61.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: Tue, 4 Jun 2019 14:44:18 +0800 In-Reply-To: <87sgsv2n54.fsf@linux.intel.com> References: <87k1ebj8vt.fsf@linux.intel.com> <1559201499.8487.40.camel@mhfsdcap03> <87sgsv2n54.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 On Fri, 2019-05-31 at 08:44 +0300, Felipe Balbi wrote: > Hi, > > Chunfeng Yun writes: > > > 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? > > I guess a simple refcount is the way to go: > > struct dentry *usb_debugfs_init(void) > { > if (!usb_debug_root) > usb_debug_root = debugfs_create_dir("usb", NULL); > > usb_debug_root_refcnt++; > return usb_debug_root; > } > > void usb_debugfs_cleanup(void) > { > if (!(--usb_debug_root_refcnt)) { > debugfs_remove_recursive(usb_debug_root); > usb_debug_root = NULL; > } > } I'll try it, thanks > > Or something along those lines >