When printer_write() calls usb_ep_queue(), a udc driver (e.g.
renesas_usbhs driver) may call usb_gadget_giveback_request() in
the udc .queue ops immediately. Then, printer_write() calls
list_add(&req->list, &dev->tx_reqs_active) wrongly. After that,
if we do unbind the printer driver, WARN_ON() happens in
printer_func_unbind() because the list entry is not removed.
So, this patch moves list_add(&req->list, &dev->tx_reqs_active)
calling before usb_ep_queue().
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Acked-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
---
Changes from RFC (v1):
- Modify the implementation to fix the issue.
- Add "Acked-by Felipe Balbi".
- Remove RFC.
- Revise commit log.
drivers/usb/gadget/function/f_printer.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c
index d359efe..9c7ed25 100644
--- a/drivers/usb/gadget/function/f_printer.c
+++ b/drivers/usb/gadget/function/f_printer.c
@@ -631,19 +631,19 @@ static void tx_complete(struct usb_ep *ep, struct usb_request *req)
return -EAGAIN;
}
+ list_add(&req->list, &dev->tx_reqs_active);
+
/* here, we unlock, and only unlock, to avoid deadlock. */
spin_unlock(&dev->lock);
value = usb_ep_queue(dev->in_ep, req, GFP_ATOMIC);
spin_lock(&dev->lock);
if (value) {
+ list_del(&req->list);
list_add(&req->list, &dev->tx_reqs);
spin_unlock_irqrestore(&dev->lock, flags);
mutex_unlock(&dev->lock_printer_io);
return -EAGAIN;
}
-
- list_add(&req->list, &dev->tx_reqs_active);
-
}
spin_unlock_irqrestore(&dev->lock, flags);
--
1.9.1
