firmware: arm_scmi: Fix handling of unexpected delayed responses

Upon reception of an unexpected bogus delayed response, clear the channel
and bail-out safely.

Link: https://lore.kernel.org/r/20200420152315.21008-5-cristian.marussi@arm.com
Fixes: 4d09852b6f01 ("firmware: arm_scmi: Add support for notifications message processing")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 07de196f15aa2cf8e899225f98e70665cc7a8b22..fec308e47b9d6d56c9bd1fc135ee4636f06c7484 100644 (file)
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -247,6 +247,21 @@ static void scmi_handle_response(struct scmi_chan_info *cinfo,
        }
 
        xfer = &minfo->xfer_block[xfer_id];
+       /*
+        * Even if a response was indeed expected on this slot at this point,
+        * a buggy platform could wrongly reply feeding us an unexpected
+        * delayed response we're not prepared to handle: bail-out safely
+        * blaming firmware.
+        */
+       if (unlikely(msg_type == MSG_TYPE_DELAYED_RESP && !xfer->async_done)) {
+               dev_err(dev,
+                       "Delayed Response for %d not expected! Buggy F/W ?\n",
+                       xfer_id);
+               info->desc->ops->clear_channel(cinfo);
+               /* It was unexpected, so nobody will clear the xfer if not us */
+               __scmi_xfer_put(minfo, xfer);
+               return;
+       }
 
        scmi_dump_header_dbg(dev, &xfer->hdr);