USB: fsl_qe_udc: Fix recursive locking bug in ch9getstatus()

The call chain is this:

qe_udc_irq() <- grabs the udc->lock spinlock
rx_irq()
qe_ep0_rx()
ep0_setup_handle()
setup_received_handle()
ch9getstatus()
qe_ep_queue() <- tries to grab the udc->lock again

It seems unsafe to temporarily drop the lock in the ch9getstatus(),
so to fix that bug the lock-less __qe_ep_queue() function
implemented and used by the ch9getstatus().

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 18 insertions, 8 deletions

diff --git a/drivers/usb/gadget/fsl_qe_udc.c b/drivers/usb/gadget/fsl_qe_udc.c
index e8f7862acb3d..064582fb6a87 100644
--- a/drivers/usb/gadget/fsl_qe_udc.c
+++ b/drivers/usb/gadget/fsl_qe_udc.c
@@ -1681,14 +1681,11 @@ static void qe_free_request(struct usb_ep *_ep, struct usb_request *_req)
                 kfree(req);
 }
 
-/* queues (submits) an I/O request to an endpoint */
-static int qe_ep_queue(struct usb_ep *_ep, struct usb_request *_req,
-                                gfp_t gfp_flags)
+static int __qe_ep_queue(struct usb_ep *_ep, struct usb_request *_req)
 {
         struct qe_ep *ep = container_of(_ep, struct qe_ep, ep);
         struct qe_req *req = container_of(_req, struct qe_req, req);
         struct qe_udc *udc;
-        unsigned long flags;
         int reval;
 
         udc = ep->udc;
@@ -1732,7 +1729,7 @@ static int qe_ep_queue(struct usb_ep *_ep, struct usb_request *_req,
         list_add_tail(&req->queue, &ep->queue);
         dev_vdbg(udc->dev, "gadget have request in %s! %d\n",
                         ep->name, req->req.length);
-        spin_lock_irqsave(&udc->lock, flags);
+
         /* push the request to device */
         if (ep_is_in(ep))
                 reval = ep_req_send(ep, req);
@@ -1748,11 +1745,24 @@ static int qe_ep_queue(struct usb_ep *_ep, struct usb_request *_req,
         if (ep->dir == USB_DIR_OUT)
                 reval = ep_req_receive(ep, req);
 
-        spin_unlock_irqrestore(&udc->lock, flags);
-
         return 0;
 }
 
+/* queues (submits) an I/O request to an endpoint */
+static int qe_ep_queue(struct usb_ep *_ep, struct usb_request *_req,
+                       gfp_t gfp_flags)
+{
+        struct qe_ep *ep = container_of(_ep, struct qe_ep, ep);
+        struct qe_udc *udc = ep->udc;
+        unsigned long flags;
+        int ret;
+
+        spin_lock_irqsave(&udc->lock, flags);
+        ret = __qe_ep_queue(_ep, _req);
+        spin_unlock_irqrestore(&udc->lock, flags);
+        return ret;
+}
+
 /* dequeues (cancels, unlinks) an I/O request from an endpoint */
 static int qe_ep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 {
@@ -2008,7 +2018,7 @@ static void ch9getstatus(struct qe_udc *udc, u8 request_type, u16 value,
         udc->ep0_dir = USB_DIR_IN;
 
         /* data phase */
-        status = qe_ep_queue(&ep->ep, &req->req, GFP_ATOMIC);
+        status = __qe_ep_queue(&ep->ep, &req->req);
 
         if (status == 0)
                 return;