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Commit c757700f authored by Danny Segal's avatar Danny Segal Committed by Mayank Rana
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usb: gadget: Resolve recursive spinlock during remote wakeup 



When a USB function wishes to send new data during USB suspend state, it
needs to issue USB remote wakeup and send a function wakeup notification
after then. This scenario leads to recursive spin locking inside the
_usb_func_wakeup() function, because this function gets called recursively.
This function issues remote wakeup, which internally calls the resume
interrupt callback, which calls the _usb_func_wakeup() function again.
This issue is resolved by performing the remote wakeup in a deferred work
context, and this splits the recursion loop.

CRs-fixed: 700667
Change-Id: I59c8efde098781587d29f08cd60e4aa3521949d8
Signed-off-by: default avatarDanny Segal <dsegal@codeaurora.org>
Signed-off-by: default avatarMayank Rana <mrana@codeaurora.org>
parent de7cd8dd

drivers/usb/gadget/composite.c

+13 −7
Original line number Diff line number Diff line
@@ -443,7 +443,8 @@ int usb_get_func_interface_id(struct usb_function *func) 
	return -ENODEV;

}



static int _usb_func_wakeup(struct usb_function *func, bool use_pending_flag)

static int usb_func_wakeup_int(struct usb_function *func,

					bool use_pending_flag)

{

	int ret;

	int interface_id;
@@ -451,8 +452,8 @@ static int _usb_func_wakeup(struct usb_function *func, bool use_pending_flag) 
	struct usb_gadget *gadget;

	struct usb_composite_dev *cdev;



	pr_debug("%s function wakeup\n",

		func->name ? func->name : "");

	pr_debug("%s - %s function wakeup, use pending: %u\n",

		__func__, func->name ? func->name : "", use_pending_flag);



	if (!func || !func->config || !func->config->cdev ||

		!func->config->cdev->gadget)
@@ -482,14 +483,20 @@ static int _usb_func_wakeup(struct usb_function *func, bool use_pending_flag) 
		ERROR(func->config->cdev,

			"Function %s - Unknown interface id. Canceling USB request. ret=%d\n",

			func->name ? func->name : "", ret);



		spin_unlock_irqrestore(&cdev->lock, flags);

		return ret;

	}



	interface_id = ret;

	ret = usb_gadget_func_wakeup(gadget, interface_id);



	if (use_pending_flag)

	if (use_pending_flag) {

		func->func_wakeup_pending = false;

	} else {

		if (ret == -EAGAIN)

			func->func_wakeup_pending = true;

	}



	spin_unlock_irqrestore(&cdev->lock, flags);
@@ -503,12 +510,11 @@ int usb_func_wakeup(struct usb_function *func) 
	pr_debug("%s function wakeup\n",

		func->name ? func->name : "");



	ret = _usb_func_wakeup(func, false);

	ret = usb_func_wakeup_int(func, false);

	if (ret == -EAGAIN) {

		DBG(func->config->cdev,

			"Function wakeup for %s could not complete due to suspend state. Delayed until after bus resume.\n",

			func->name ? func->name : "");

		func->func_wakeup_pending = true;

		ret = 0;

	} else if (ret < 0) {

		ERROR(func->config->cdev,
@@ -2426,7 +2432,7 @@ void composite_resume(struct usb_gadget *gadget) 


	if (cdev->config) {

		list_for_each_entry(f, &cdev->config->functions, list) {

			ret = _usb_func_wakeup(f, true);

			ret = usb_func_wakeup_int(f, true);

			if (ret) {

				if (ret == -EAGAIN) {

					ERROR(f->config->cdev,