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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 Wed, Jun 05, 2019 at 03:50:31PM +0800, Chunfeng Yun wrote: > 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. Ah, let me fix that, it should have the same init level and I'll ensure it comes first in the linking. > 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 Wonderful! Let me fix up the init level, and the build issue tha kbuild found, and post a v2 patch. thanks, greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel