usb: dwc3: core: remove lock of otg mode during gadget suspend/resume to avoid deadlock

When config CONFIG_USB_DWC3_DUAL_ROLE is selected, and trigger system
to enter suspend status with below command:
echo mem > /sys/power/state
There will be a deadlock issue occurring. Detailed invoking path as
below:
dwc3_suspend_common()
    spin_lock_irqsave(&dwc->lock, flags);              <-- 1st
    dwc3_gadget_suspend(dwc);
        dwc3_gadget_soft_disconnect(dwc);
            spin_lock_irqsave(&dwc->lock, flags);      <-- 2nd
This issue is exposed by commit c7ebd81 ("usb: dwc3: gadget: Fix
NULL pointer dereference in dwc3_gadget_suspend") that removes the code
of checking whether dwc->gadget_driver is NULL or not. It causes the
following code is executed and deadlock occurs when trying to get the
spinlock. In fact, the root cause is the commit 5265397("usb: dwc3:
Remove DWC3 locking during gadget suspend/resume") that forgot to remove
the lock of otg mode. So, remove the redundant lock of otg mode during
gadget suspend/resume.

Fixes: 5265397 ("usb: dwc3: Remove DWC3 locking during gadget suspend/resume")
Cc: Xu Yang <[email protected]>
Cc: [email protected]
Signed-off-by: Meng Li <[email protected]>
Acked-by: Thinh Nguyen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: limeng-linux

drivers/usb/dwc3/core.c

@@ -2250,7 +2250,6 @@ static int dwc3_core_init_for_resume(struct dwc3 *dwc)
 
 static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 {
-	unsigned long	flags;
 	u32 reg;
 	int i;
 
@@ -2293,9 +2292,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 			break;
 
 		if (dwc->current_otg_role == DWC3_OTG_ROLE_DEVICE) {
-			spin_lock_irqsave(&dwc->lock, flags);
 			dwc3_gadget_suspend(dwc);
-			spin_unlock_irqrestore(&dwc->lock, flags);
 			synchronize_irq(dwc->irq_gadget);
 		}
 
@@ -2312,7 +2309,6 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 
 static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
 {
-	unsigned long	flags;
 	int		ret;
 	u32		reg;
 	int		i;
@@ -2366,9 +2362,7 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
 		if (dwc->current_otg_role == DWC3_OTG_ROLE_HOST) {
 			dwc3_otg_host_init(dwc);
 		} else if (dwc->current_otg_role == DWC3_OTG_ROLE_DEVICE) {
-			spin_lock_irqsave(&dwc->lock, flags);
 			dwc3_gadget_resume(dwc);
-			spin_unlock_irqrestore(&dwc->lock, flags);
 		}
 
 		break;