1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/usb/gadget/f_acm.c b/drivers/usb/gadget/f_acm.c
index 5ee1590b8e9..c1d34df0b15 100644
--- a/drivers/usb/gadget/f_acm.c
+++ b/drivers/usb/gadget/f_acm.c
@@ -463,7 +463,11 @@ static int acm_cdc_notify(struct f_acm *acm, u8 type, u16 value,
         notify->wLength = cpu_to_le16(length);
         memcpy(buf, data, length);
 
+        /* ep_queue() can complete immediately if it fills the fifo... */
+        spin_unlock(&acm->lock);
         status = usb_ep_queue(ep, req, GFP_ATOMIC);
+        spin_lock(&acm->lock);
+
         if (status < 0) {
                 ERROR(acm->port.func.config->cdev,
                                 "acm ttyGS%d can't notify serial state, %d\n",