[v2 PATCH] usb: dwc3: core: remove lock of otg mode during gadget suspend/resume to avoid deadlock

Meng Li
2024-06-18T03:19:57Z

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 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. In fact, the root cause is the commit 5265397f9442("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: 5265397f9442 ("usb: dwc3: Remove DWC3 locking during gadget suspend/resume")
Cc: Xu Yang <xu.yang_2@nxp.com>
Cc: stable@vger.kernel.org
Signed-off-by: Meng Li <Meng.Li@windriver.com>

---
v1->v2:
- improve commit log, correct the Fixes commit id.

---
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 7ee61a89520b..9d47c3aa5777 100644
--- a/drivers/usb/dwc3/core.c
+++ b/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;
--
2.34.1