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* [v3 PATCH] usb: create usb_debug_root for gadget only
@ 2019-05-28  7:54 Chunfeng Yun
  2019-05-28  8:11 ` Felipe Balbi
  2019-05-28  8:24 ` Chunfeng Yun
  0 siblings, 2 replies; 7+ messages in thread
From: Chunfeng Yun @ 2019-05-28  7:54 UTC (permalink / raw)
  To: Greg Kroah-Hartman
  Cc: Matthias Brugger, Randy Dunlap, Chunfeng Yun, linux-usb,
	linux-arm-kernel, linux-mediatek, linux-kernel

When CONFIG_USB is not set, and CONFIG_USB_GADGET is set,
there is an issue, e.g.:

drivers/usb/mtu3/mtu3_debugfs.o: in function 'ssusb_debugfs_create_root':
mtu3_debugfs.c:(.text+0xba3): undefined reference to 'usb_debug_root'

usb_debug_root is currently only built when host is supported
(CONFIG_USB is set), for convenience, we also want it created when
gadget only is enabled, this patch try to support it.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
v3:
  1. still create usb_debug_root for gadget only
  2. abandon mtu3's change
  3. drop acked-by Randy

v2(resend): add acked-by Randy

v1: fix mtu3's build error, replace usb_debug_root by NULL;
---
 drivers/usb/core/usb.c        |  2 +-
 drivers/usb/gadget/udc/core.c | 27 +++++++++++++++++++++++++++
 include/linux/usb.h           |  1 +
 3 files changed, 29 insertions(+), 1 deletion(-)

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);
 }
diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 7cf34beb50df..ed45f9429e58 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -8,6 +8,7 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/list.h>
 #include <linux/err.h>
@@ -1587,12 +1588,37 @@ static int usb_udc_uevent(struct device *dev, struct kobj_uevent_env *env)
 	return 0;
 }
 
+/* if CONFIG_USB is set, leave USB core to create usb_debug_root */
+#ifndef CONFIG_USB
+struct dentry *usb_debug_root;
+EXPORT_SYMBOL_GPL(usb_debug_root);
+
+static void usb_debugfs_init(void)
+{
+	usb_debug_root = debugfs_create_dir(USB_DEBUG_ROOT_NAME, NULL);
+}
+
+static void usb_debugfs_cleanup(void)
+{
+	debugfs_remove_recursive(usb_debug_root);
+}
+#else
+static void usb_debugfs_init(void)
+{}
+
+static void usb_debugfs_cleanup(void)
+{}
+#endif
+
 static int __init usb_udc_init(void)
 {
+	usb_debugfs_init();
+
 	udc_class = class_create(THIS_MODULE, "udc");
 	if (IS_ERR(udc_class)) {
 		pr_err("failed to create udc class --> %ld\n",
 				PTR_ERR(udc_class));
+		usb_debugfs_cleanup();
 		return PTR_ERR(udc_class);
 	}
 
@@ -1604,6 +1630,7 @@ subsys_initcall(usb_udc_init);
 static void __exit usb_udc_exit(void)
 {
 	class_destroy(udc_class);
+	usb_debugfs_cleanup();
 }
 module_exit(usb_udc_exit);
 
diff --git a/include/linux/usb.h b/include/linux/usb.h
index ae82d9d1112b..9c6e7b3265af 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1994,6 +1994,7 @@ extern void usb_register_notify(struct notifier_block *nb);
 extern void usb_unregister_notify(struct notifier_block *nb);
 
 /* debugfs stuff */
+#define USB_DEBUG_ROOT_NAME	"usb"
 extern struct dentry *usb_debug_root;
 
 /* LED triggers */
-- 
2.21.0


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [v3 PATCH] usb: create usb_debug_root for gadget only
  2019-05-28  7:54 [v3 PATCH] usb: create usb_debug_root for gadget only Chunfeng Yun
@ 2019-05-28  8:11 ` Felipe Balbi
  2019-05-28  8:49   ` Chunfeng Yun
  2019-05-30  7:31   ` Chunfeng Yun
  2019-05-28  8:24 ` Chunfeng Yun
  1 sibling, 2 replies; 7+ messages in thread
From: Felipe Balbi @ 2019-05-28  8:11 UTC (permalink / raw)
  To: Chunfeng Yun, Greg Kroah-Hartman
  Cc: Matthias Brugger, Randy Dunlap, Chunfeng Yun, linux-usb,
	linux-arm-kernel, linux-mediatek, linux-kernel


Hi,

Chunfeng Yun <chunfeng.yun@mediatek.com> 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);
}

-- 
balbi

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [v3 PATCH] usb: create usb_debug_root for gadget only
  2019-05-28  7:54 [v3 PATCH] usb: create usb_debug_root for gadget only Chunfeng Yun
  2019-05-28  8:11 ` Felipe Balbi
@ 2019-05-28  8:24 ` Chunfeng Yun
  1 sibling, 0 replies; 7+ messages in thread
From: Chunfeng Yun @ 2019-05-28  8:24 UTC (permalink / raw)
  To: Greg Kroah-Hartman, Felipe Balbi
  Cc: Matthias Brugger, Randy Dunlap, linux-usb, linux-arm-kernel,
	linux-mediatek, linux-kernel

add Felipe, sorry

On Tue, 2019-05-28 at 15:54 +0800, Chunfeng Yun wrote:
> When CONFIG_USB is not set, and CONFIG_USB_GADGET is set,
> there is an issue, e.g.:
> 
> drivers/usb/mtu3/mtu3_debugfs.o: in function 'ssusb_debugfs_create_root':
> mtu3_debugfs.c:(.text+0xba3): undefined reference to 'usb_debug_root'
> 
> usb_debug_root is currently only built when host is supported
> (CONFIG_USB is set), for convenience, we also want it created when
> gadget only is enabled, this patch try to support it.
> 
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> ---
> v3:
>   1. still create usb_debug_root for gadget only
>   2. abandon mtu3's change
>   3. drop acked-by Randy
> 
> v2(resend): add acked-by Randy
> 
> v1: fix mtu3's build error, replace usb_debug_root by NULL;
> ---
>  drivers/usb/core/usb.c        |  2 +-
>  drivers/usb/gadget/udc/core.c | 27 +++++++++++++++++++++++++++
>  include/linux/usb.h           |  1 +
>  3 files changed, 29 insertions(+), 1 deletion(-)
> 
> 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);
>  }
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 7cf34beb50df..ed45f9429e58 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -8,6 +8,7 @@
>  
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/debugfs.h>
>  #include <linux/device.h>
>  #include <linux/list.h>
>  #include <linux/err.h>
> @@ -1587,12 +1588,37 @@ static int usb_udc_uevent(struct device *dev, struct kobj_uevent_env *env)
>  	return 0;
>  }
>  
> +/* if CONFIG_USB is set, leave USB core to create usb_debug_root */
> +#ifndef CONFIG_USB
> +struct dentry *usb_debug_root;
> +EXPORT_SYMBOL_GPL(usb_debug_root);
> +
> +static void usb_debugfs_init(void)
> +{
> +	usb_debug_root = debugfs_create_dir(USB_DEBUG_ROOT_NAME, NULL);
> +}
> +
> +static void usb_debugfs_cleanup(void)
> +{
> +	debugfs_remove_recursive(usb_debug_root);
> +}
> +#else
> +static void usb_debugfs_init(void)
> +{}
> +
> +static void usb_debugfs_cleanup(void)
> +{}
> +#endif
> +
>  static int __init usb_udc_init(void)
>  {
> +	usb_debugfs_init();
> +
>  	udc_class = class_create(THIS_MODULE, "udc");
>  	if (IS_ERR(udc_class)) {
>  		pr_err("failed to create udc class --> %ld\n",
>  				PTR_ERR(udc_class));
> +		usb_debugfs_cleanup();
>  		return PTR_ERR(udc_class);
>  	}
>  
> @@ -1604,6 +1630,7 @@ subsys_initcall(usb_udc_init);
>  static void __exit usb_udc_exit(void)
>  {
>  	class_destroy(udc_class);
> +	usb_debugfs_cleanup();
>  }
>  module_exit(usb_udc_exit);
>  
> diff --git a/include/linux/usb.h b/include/linux/usb.h
> index ae82d9d1112b..9c6e7b3265af 100644
> --- a/include/linux/usb.h
> +++ b/include/linux/usb.h
> @@ -1994,6 +1994,7 @@ extern void usb_register_notify(struct notifier_block *nb);
>  extern void usb_unregister_notify(struct notifier_block *nb);
>  
>  /* debugfs stuff */
> +#define USB_DEBUG_ROOT_NAME	"usb"
>  extern struct dentry *usb_debug_root;
>  
>  /* LED triggers */



^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [v3 PATCH] usb: create usb_debug_root for gadget only
  2019-05-28  8:11 ` Felipe Balbi
@ 2019-05-28  8:49   ` Chunfeng Yun
  2019-05-30  7:31   ` Chunfeng Yun
  1 sibling, 0 replies; 7+ messages in thread
From: Chunfeng Yun @ 2019-05-28  8:49 UTC (permalink / raw)
  To: Felipe Balbi
  Cc: Greg Kroah-Hartman, Matthias Brugger, Randy Dunlap, linux-usb,
	linux-arm-kernel, linux-mediatek, linux-kernel

Hi Felipe,
On Tue, 2019-05-28 at 11:11 +0300, Felipe Balbi wrote:
> Hi,
> 
> Chunfeng Yun <chunfeng.yun@mediatek.com> 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. 
Good idea, I forgot there is a common file.

> Then have a function
> which can be called by both host and gadget to maybe create the
> directory:
I'll try it.

Thanks a lot

> 
> 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);
> }
> 



^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [v3 PATCH] usb: create usb_debug_root for gadget only
  2019-05-28  8:11 ` Felipe Balbi
  2019-05-28  8:49   ` Chunfeng Yun
@ 2019-05-30  7:31   ` Chunfeng Yun
  2019-05-31  5:44     ` Felipe Balbi
  1 sibling, 1 reply; 7+ messages in thread
From: Chunfeng Yun @ 2019-05-30  7:31 UTC (permalink / raw)
  To: Felipe Balbi
  Cc: Greg Kroah-Hartman, Matthias Brugger, Randy Dunlap, linux-usb,
	linux-arm-kernel, linux-mediatek, linux-kernel

Hi Felipe,
On Tue, 2019-05-28 at 11:11 +0300, Felipe Balbi wrote:
> Hi,
> 
> Chunfeng Yun <chunfeng.yun@mediatek.com> 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






^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [v3 PATCH] usb: create usb_debug_root for gadget only
  2019-05-30  7:31   ` Chunfeng Yun
@ 2019-05-31  5:44     ` Felipe Balbi
  2019-06-04  6:44       ` Chunfeng Yun
  0 siblings, 1 reply; 7+ messages in thread
From: Felipe Balbi @ 2019-05-31  5:44 UTC (permalink / raw)
  To: Chunfeng Yun
  Cc: Greg Kroah-Hartman, Matthias Brugger, Randy Dunlap, linux-usb,
	linux-arm-kernel, linux-mediatek, linux-kernel


Hi,

Chunfeng Yun <chunfeng.yun@mediatek.com> writes:

> Hi Felipe,
> On Tue, 2019-05-28 at 11:11 +0300, Felipe Balbi wrote:
>> Hi,
>> 
>> Chunfeng Yun <chunfeng.yun@mediatek.com> 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;
	}
}

Or something along those lines

-- 
balbi

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [v3 PATCH] usb: create usb_debug_root for gadget only
  2019-05-31  5:44     ` Felipe Balbi
@ 2019-06-04  6:44       ` Chunfeng Yun
  0 siblings, 0 replies; 7+ messages in thread
From: Chunfeng Yun @ 2019-06-04  6:44 UTC (permalink / raw)
  To: Felipe Balbi
  Cc: Greg Kroah-Hartman, Matthias Brugger, Randy Dunlap, linux-usb,
	linux-arm-kernel, linux-mediatek, linux-kernel

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



^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2019-06-04  6:44 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-28  7:54 [v3 PATCH] usb: create usb_debug_root for gadget only Chunfeng Yun
2019-05-28  8:11 ` Felipe Balbi
2019-05-28  8:49   ` Chunfeng Yun
2019-05-30  7:31   ` Chunfeng Yun
2019-05-31  5:44     ` Felipe Balbi
2019-06-04  6:44       ` Chunfeng Yun
2019-05-28  8:24 ` Chunfeng Yun

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