ipmi:si: Handle waiting messages when BMC failure detected

If a BMC failure is detected, the current message is returned with an
error.  However, if there was a waiting message, it would not be
handled.

Add a check for the waiting message after handling the current message.

Suggested-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Rafael J. Wysocki <rafael@kernel.org>
Closes: https://lore.kernel.org/linux-acpi/CAK8fFZ58fidGUCHi5WFX0uoTPzveUUDzT=k=AAm4yWo3bAuCFg@mail.gmail.com/
Fixes: bc3a9d2 ("ipmi:si: Gracefully handle if the BMC is non-functional")
Cc: stable@vger.kernel.org # 4.18
Signed-off-by: Corey Minyard <corey@minyard.net>

Author: cminyard

drivers/char/ipmi/ipmi_si_intf.c

@@ -809,6 +809,12 @@ static enum si_sm_result smi_event_handler(struct smi_info *smi_info,
 			 */
 			return_hosed_msg(smi_info, IPMI_BUS_ERR);
 		}
+		if (smi_info->waiting_msg != NULL) {
+			/* Also handle if there was a message waiting. */
+			smi_info->curr_msg = smi_info->waiting_msg;
+			smi_info->waiting_msg = NULL;
+			return_hosed_msg(smi_info, IPMI_BUS_ERR);
+		}
 		smi_mod_timer(smi_info, jiffies + SI_TIMEOUT_HOSED);
 		goto out;
 	}