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

Thinh Nguyen
2024-06-18T21:54:15Z

On Tue, Jun 18, 2024, Meng Li wrote:
> 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
>

Did you use "git format-patch -v"? The $subject version prefix order is
different. In any case,

Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>

Thanks,
Thinh