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>

diff --git a/drivers/usb/gadget/fsl_qe_udc.c b/drivers/usb/gadget/fsl_qe_udc.c
index e8f7862..064582f 100644 (file)
--- 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;