linux-kernel - [PATCH] usb: dwc3: core: remove lock of otg mode during gadget suspend/resume to avoid deadlock

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Message-Id: <20240613072310.1927966-1-Meng.Li@windriver.com>
Date: Thu, 13 Jun 2024 15:23:10 +0800
From: Meng Li <Meng.Li@...driver.com>
To: Thinh.Nguyen@...opsys.com, gregkh@...uxfoundation.org,
        quic_uaggarwa@...cinc.com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc: meng.li@...driver.com
Subject: [PATCH] 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. Because dwc3_gadget_suspend() also
try to get the lock again when previous invoked dwc3_suspend_common() has
got the lock . This issue is introduced by commit c7ebd8149ee5 ("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.
To fix the deadlock issue, refer to commit 5265397f9442("usb: dwc3: Remove
DWC3 locking during gadget suspend/resume"), remove lock of otg mode during
gadget suspend/resume.

Fixes: c7ebd8149ee5 ("Fix NULL pointer dereference in dwc3_gadget_suspend")
Cc: stable@...r.kernel.org
Signed-off-by: Meng Li <Meng.Li@...driver.com>
---
 drivers/usb/dwc3/core.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index a8fb10cc65bc..9bb4ab409bbb 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -2112,7 +2112,6 @@ 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;
 
 	switch (dwc->current_dr_role) {
@@ -2150,9 +2149,7 @@ 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);
 		}
 
@@ -2169,7 +2166,6 @@ 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;
 
@@ -2227,9 +2223,7 @@ 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;
-- 
2.34.1