From 7732495c599c0b98ff17097637f239e1ef108e69 Mon Sep 17 00:00:00 2001
From: Felipe Balbi <felipe.balbi@linux.intel.com>
Date: Mon, 26 Mar 2018 13:14:46 +0300
Subject: [PATCH] usb: gadget: udc: core: update usb_ep_queue() documentation

commit eaa358c7790338d83bb6a31258bdc077de120414 upstream.

Mention that ->complete() should never be called from within
usb_ep_queue().

Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/gadget/udc/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 794bb4958383..5bab09294a8a 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -249,6 +249,9 @@ EXPORT_SYMBOL_GPL(usb_ep_free_request);
  * arranges to poll once per interval, and the gadget driver usually will
  * have queued some data to transfer at that time.
  *
+ * Note that @req's ->complete() callback must never be called from
+ * within usb_ep_queue() as that can create deadlock situations.
+ *
  * Returns zero, or a negative error code.  Endpoints that are not enabled
  * report errors; errors will also be
  * reported when the usb peripheral is disconnected.