On Fri, 2019-05-31 at 08:44 +0300, Felipe Balbi wrote:
> Hi,
>
> Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx> writes:
>
> > Hi Felipe,
> > On Tue, 2019-05-28 at 11:11 +0300, Felipe Balbi wrote:
> >> Hi,
> >>
> >> Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx> 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
>
