From: Stephen Warren swarren@nvidia.com
The flipping of ep0 between IN and OUT relies on ci_ep_queue() consuming the current IN/OUT setting immediately. If this is deferred to a later point when the req is pulled out of ci_req->queue, then the IN/OUT setting may have been changed since the req was queued, and state will get out of sync. This condition doesn't occur today, but could if bugs were introduced later, and this error-check will save a lot of debugging time.
Signed-off-by: Stephen Warren swarren@nvidia.com --- drivers/usb/gadget/ci_udc.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/drivers/usb/gadget/ci_udc.c b/drivers/usb/gadget/ci_udc.c index 9cd003636a44..a68a85f84e70 100644 --- a/drivers/usb/gadget/ci_udc.c +++ b/drivers/usb/gadget/ci_udc.c @@ -397,6 +397,21 @@ static int ci_ep_queue(struct usb_ep *ep, num = ci_ep->desc->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK; in = (ci_ep->desc->bEndpointAddress & USB_DIR_IN) != 0;
+ if (!num && ci_ep->req_primed) { + /* + * The flipping of ep0 between IN and OUT relies on + * ci_ep_queue consuming the current IN/OUT setting + * immediately. If this is deferred to a later point when the + * req is pulled out of ci_req->queue, then the IN/OUT setting + * may have been changed since the req was queued, and state + * will get out of sync. This condition doesn't occur today, + * but could if bugs were introduced later, and this error + * check will save a lot of debugging time. + */ + printf("%s: ep0 transaction already in progress\n", __func__); + return -EPROTO; + } + ret = ci_bounce(ci_req, in); if (ret) return ret;