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Commit 0726ee55 authored by Will Deacon's avatar Will Deacon Committed by Giuliano Procida
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ANDROID: usb: f_accessory: Add refcounting to global 'acc_dev' 



Add refcounting to track the lifetime of the global 'acc_dev' structure,
as the underlying function directories can be removed while references
still exist to the dev node.

Bug: 173789633
Signed-off-by: default avatarWill Deacon <willdeacon@google.com>
Change-Id: I248408e890d01167706c329146d63b64a6456df6
Signed-off-by: default avatarGiuliano Procida <gprocida@google.com>
parent 21183c4d

drivers/usb/gadget/function/f_accessory.c

+32 −6
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <linux/interrupt.h>

#include <linux/kthread.h>

#include <linux/freezer.h>

#include <linux/kref.h>



#include <linux/types.h>

#include <linux/file.h>
@@ -73,6 +74,7 @@ struct acc_dev { 
	struct usb_function function;

	struct usb_composite_dev *cdev;

	spinlock_t lock;

	struct acc_dev_ref *ref;



	struct usb_ep *ep_in;

	struct usb_ep *ep_out;
@@ -199,7 +201,14 @@ static struct usb_gadget_strings *acc_strings[] = { 
	NULL,

};



static struct acc_dev *_acc_dev;

struct acc_dev_ref {

	struct kref	kref;

	struct acc_dev	*acc_dev;

};



static struct acc_dev_ref _acc_dev_ref = {

	.kref = KREF_INIT(0),

};



struct acc_instance {

	struct usb_function_instance func_inst;
@@ -208,11 +217,26 @@ struct acc_instance { 


static struct acc_dev *get_acc_dev(void)

{

	return _acc_dev;

	struct acc_dev_ref *ref = &_acc_dev_ref;



	return kref_get_unless_zero(&ref->kref) ? ref->acc_dev : NULL;

}



static void __put_acc_dev(struct kref *kref)

{

	struct acc_dev_ref *ref = container_of(kref, struct acc_dev_ref, kref);

	struct acc_dev *dev = ref->acc_dev;



	ref->acc_dev = NULL;

	kfree(dev);

}



static void put_acc_dev(struct acc_dev *dev)

{

	struct acc_dev_ref *ref = dev->ref;



	WARN_ON(ref->acc_dev != dev);

	kref_put(&ref->kref, __put_acc_dev);

}



static inline struct acc_dev *func_to_dev(struct usb_function *f)
@@ -1230,6 +1254,7 @@ static void acc_function_disable(struct usb_function *f) 


static int acc_setup(void)

{

	struct acc_dev_ref *ref = &_acc_dev_ref;

	struct acc_dev *dev;

	int ret;
@@ -1248,7 +1273,9 @@ static int acc_setup(void) 
	INIT_DELAYED_WORK(&dev->start_work, acc_start_work);

	INIT_WORK(&dev->hid_work, acc_hid_work);



	_acc_dev = dev;

	dev->ref = ref;

	kref_init(&ref->kref);

	ref->acc_dev = dev;



	ret = misc_register(&acc_device);

	if (ret)
@@ -1276,12 +1303,11 @@ EXPORT_SYMBOL_GPL(acc_disconnect); 


static void acc_cleanup(void)

{

	struct acc_dev *dev = _acc_dev;

	struct acc_dev *dev = get_acc_dev();



	misc_deregister(&acc_device);

	put_acc_dev(dev);

	kfree(dev);

	_acc_dev = NULL;

	put_acc_dev(dev); /* Pairs with kref_init() in acc_setup() */

}

static struct acc_instance *to_acc_instance(struct config_item *item)

{