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Wed, 5 Jun 2019 15:50:31 +0800 Message-ID: <1559721031.8487.99.camel@mhfsdcap03> Subject: Re: [PATCH] USB: move usb debugfs directory creation to the usb common core From: Chunfeng Yun To: Greg Kroah-Hartman Date: Wed, 5 Jun 2019 15:50:31 +0800 In-Reply-To: <20190604115919.GA24346@kroah.com> References: <20190604093258.GB30054@kroah.com> <20190604115919.GA24346@kroah.com> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190605_005041_695377_6DED33BD X-CRM114-Status: GOOD ( 20.41 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devicetree@vger.kernel.org, Felipe Balbi , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, Matthias Brugger , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 2019-06-04 at 13:59 +0200, Greg Kroah-Hartman wrote: > On Tue, Jun 04, 2019 at 11:32:58AM +0200, Greg Kroah-Hartman wrote: > > The USB gadget subsystem wants to use the USB debugfs root directory, so > > move it to the common "core" USB code so that it is properly initialized > > and removed as needed. > > > > Signed-off-by: Greg Kroah-Hartman > > > > --- > > > > This should be the "correct" version of this, Chunfeng, can you test > > this to verify it works for you? > > > > > > diff --git a/drivers/usb/common/common.c b/drivers/usb/common/common.c > > index 18f5dcf58b0d..3b5e4263ffef 100644 > > --- a/drivers/usb/common/common.c > > +++ b/drivers/usb/common/common.c > > @@ -15,6 +15,7 @@ > > #include > > #include > > #include > > +#include > > > > static const char *const ep_type_names[] = { > > [USB_ENDPOINT_XFER_CONTROL] = "ctrl", > > @@ -291,4 +292,21 @@ struct device *usb_of_get_companion_dev(struct device *dev) > > EXPORT_SYMBOL_GPL(usb_of_get_companion_dev); > > #endif > > > > +struct dentry *usb_debug_root; > > +EXPORT_SYMBOL_GPL(usb_debug_root); > > + > > +static int usb_common_init(void) > > +{ > > + usb_debug_root = debugfs_create_dir("usb", NULL); > > + return 0; > > +} > > + > > +static void usb_common_exit(void) > > +{ > > + debugfs_remove_recursive(usb_debug_root); > > +} > > + > > +module_init(usb_common_init); I tested this patch. Here use module_init() indeed have a race as Felipe said before. usbcore uses subsys_initcall(), and have a higher priority than module_init(), so when usbcore tries to create "devices" file, usb_debug_root is not created. after I replace it by postcore_initcall() (debugfs uses core_initcall()), test two cases: 1. buildin usbcore/udc-core "usb" directory is created, and usb/devices file is also created by usbcore 2. build both usbcore and gadget as ko usbcore.ko, udc-core.ko and usb-common.ko are created. 2.1 insmod usb-common.ko // "usb" directory is created insmod usb-core.ko // usb/devices file is created 2.2 rmmod usb-common.ko // failed, usb_common is in use by usb-core 2.3 rmmod usb-core.ko // usb/devices file is destroyed rmmod usb-common.ko // usb directory is destroyed 2.4 insmod usb-common.ko // "usb" directory is created insmod udc-core.ko 2.5 rmmod usb-common.ko // failed, usb_common is in use by udc-core 2.6 rmmod udc-core.ko rmmod usb-common.ko // usb directory is destroyed they are all in line with expectations > > +module_exit(usb_common_exit); > > + > > MODULE_LICENSE("GPL"); > > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c > > index 7fcb9f782931..f3d6b1ab80cb 100644 > > --- a/drivers/usb/core/usb.c > > +++ b/drivers/usb/core/usb.c > > @@ -1185,19 +1185,17 @@ static struct notifier_block usb_bus_nb = { > > .notifier_call = usb_bus_notify, > > }; > > > > -struct dentry *usb_debug_root; > > -EXPORT_SYMBOL_GPL(usb_debug_root); > > +static struct dentry *usb_devices_root; > > > > static void usb_debugfs_init(void) > > { > > - usb_debug_root = debugfs_create_dir("usb", NULL); > > - debugfs_create_file("devices", 0444, usb_debug_root, NULL, > > - &usbfs_devices_fops); > > + usb_devices_root = debugfs_create_file("devices", 0444, usb_debug_root, > > + NULL, &usbfs_devices_fops); > > } > > > > static void usb_debugfs_cleanup(void) > > { > > - debugfs_remove_recursive(usb_debug_root); > > + debugfs_remove_recursive(usb_devices_root); > > That should just be debugfs_remove(); > > I'll fix it up after someone tests this :) > > thanks, > > greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel