[PATCH v3 1/1] usb: cdns3: gadget: own the lock wrongly at the suspend routine

[PATCH v3 1/1] usb: cdns3: gadget: own the lock wrongly at the suspend routine

[Peter Chen]

When the system goes to suspend, if the controller is at device mode with
cable connecting to host, the call stack is: cdns3_suspend->
cdns3_gadget_suspend -> cdns3_disconnect_gadget, after cdns3_disconnect_gadget
is called, it owns lock wrongly, it causes the system being deadlock after
resume due to at cdns3_device_thread_irq_handler, it tries to get the lock,
but can't get it forever.

To fix it, we delete the unlock-lock operations at cdns3_disconnect_gadget,
and do it at the caller.

Fixes: b1234e3b3b26 ("usb: cdns3: add runtime PM support")
Signed-off-by: Peter Chen <peter.chen@nxp.com>
---
Changes for v3:
- Add __must_hold sparse checker

 drivers/usb/cdns3/gadget.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
index 6ff3aa3db497..8e02ccdbd4c5 100644
--- a/drivers/usb/cdns3/gadget.c
+++ b/drivers/usb/cdns3/gadget.c
@@ -1744,11 +1744,8 @@ static int cdns3_check_ep_interrupt_proceed(struct cdns3_endpoint *priv_ep)
 
 static void cdns3_disconnect_gadget(struct cdns3_device *priv_dev)
 {
-	if (priv_dev->gadget_driver && priv_dev->gadget_driver->disconnect) {
-		spin_unlock(&priv_dev->lock);
+	if (priv_dev->gadget_driver && priv_dev->gadget_driver->disconnect)
 		priv_dev->gadget_driver->disconnect(&priv_dev->gadget);
-		spin_lock(&priv_dev->lock);
-	}
 }
 
 /**
@@ -1759,6 +1756,7 @@ static void cdns3_disconnect_gadget(struct cdns3_device *priv_dev)
  */
 static void cdns3_check_usb_interrupt_proceed(struct cdns3_device *priv_dev,
 					      u32 usb_ists)
+__must_hold(&priv_dev->lock)
 {
 	int speed = 0;
 
@@ -1783,7 +1781,9 @@ static void cdns3_check_usb_interrupt_proceed(struct cdns3_device *priv_dev,
 
 	/* Disconnection detected */
 	if (usb_ists & (USB_ISTS_DIS2I | USB_ISTS_DISI)) {
+		spin_unlock(&priv_dev->lock);
 		cdns3_disconnect_gadget(priv_dev);
+		spin_lock(&priv_dev->lock);
 		priv_dev->gadget.speed = USB_SPEED_UNKNOWN;
 		usb_gadget_set_state(&priv_dev->gadget, USB_STATE_NOTATTACHED);
 		cdns3_hw_reset_eps_config(priv_dev);
@@ -3263,10 +3263,13 @@ static int __cdns3_gadget_init(struct cdns3 *cdns)
 }
 
 static int cdns3_gadget_suspend(struct cdns3 *cdns, bool do_wakeup)
+__must_hold(&cdns->lock)
 {
 	struct cdns3_device *priv_dev = cdns->gadget_dev;
 
+	spin_unlock(&cdns->lock);
 	cdns3_disconnect_gadget(priv_dev);
+	spin_lock(&cdns->lock);
 
 	priv_dev->gadget.speed = USB_SPEED_UNKNOWN;
 	usb_gadget_set_state(&priv_dev->gadget, USB_STATE_NOTATTACHED);
-- 
2.17.1

RE: [PATCH v3 1/1] usb: cdns3: gadget: own the lock wrongly at the suspend routine

[Pawel Laszczak]

>
>When the system goes to suspend, if the controller is at device mode with
>cable connecting to host, the call stack is: cdns3_suspend->
>cdns3_gadget_suspend -> cdns3_disconnect_gadget, after cdns3_disconnect_gadget
>is called, it owns lock wrongly, it causes the system being deadlock after
>resume due to at cdns3_device_thread_irq_handler, it tries to get the lock,
>but can't get it forever.
>
>To fix it, we delete the unlock-lock operations at cdns3_disconnect_gadget,
>and do it at the caller.
>
>Fixes: b1234e3b3b26 ("usb: cdns3: add runtime PM support")
>Signed-off-by: Peter Chen <peter.chen@nxp.com>

Acked-by: Pawel Laszczak <pawell@cadence.com>

>---
>Changes for v3:
>- Add __must_hold sparse checker
>
> drivers/usb/cdns3/gadget.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
>diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
>index 6ff3aa3db497..8e02ccdbd4c5 100644
>--- a/drivers/usb/cdns3/gadget.c
>+++ b/drivers/usb/cdns3/gadget.c
>@@ -1744,11 +1744,8 @@ static int cdns3_check_ep_interrupt_proceed(struct cdns3_endpoint *priv_ep)
>
> static void cdns3_disconnect_gadget(struct cdns3_device *priv_dev)
> {
>-	if (priv_dev->gadget_driver && priv_dev->gadget_driver->disconnect) {
>-		spin_unlock(&priv_dev->lock);
>+	if (priv_dev->gadget_driver && priv_dev->gadget_driver->disconnect)
> 		priv_dev->gadget_driver->disconnect(&priv_dev->gadget);
>-		spin_lock(&priv_dev->lock);
>-	}
> }
>
> /**
>@@ -1759,6 +1756,7 @@ static void cdns3_disconnect_gadget(struct cdns3_device *priv_dev)
>  */
> static void cdns3_check_usb_interrupt_proceed(struct cdns3_device *priv_dev,
> 					      u32 usb_ists)
>+__must_hold(&priv_dev->lock)
> {
> 	int speed = 0;
>
>@@ -1783,7 +1781,9 @@ static void cdns3_check_usb_interrupt_proceed(struct cdns3_device *priv_dev,
>
> 	/* Disconnection detected */
> 	if (usb_ists & (USB_ISTS_DIS2I | USB_ISTS_DISI)) {
>+		spin_unlock(&priv_dev->lock);
> 		cdns3_disconnect_gadget(priv_dev);
>+		spin_lock(&priv_dev->lock);
> 		priv_dev->gadget.speed = USB_SPEED_UNKNOWN;
> 		usb_gadget_set_state(&priv_dev->gadget, USB_STATE_NOTATTACHED);
> 		cdns3_hw_reset_eps_config(priv_dev);
>@@ -3263,10 +3263,13 @@ static int __cdns3_gadget_init(struct cdns3 *cdns)
> }
>
> static int cdns3_gadget_suspend(struct cdns3 *cdns, bool do_wakeup)
>+__must_hold(&cdns->lock)
> {
> 	struct cdns3_device *priv_dev = cdns->gadget_dev;
>
>+	spin_unlock(&cdns->lock);
> 	cdns3_disconnect_gadget(priv_dev);
>+	spin_lock(&cdns->lock);
>
> 	priv_dev->gadget.speed = USB_SPEED_UNKNOWN;
> 	usb_gadget_set_state(&priv_dev->gadget, USB_STATE_NOTATTACHED);
>--
>2.17.1