--- a/sys/dev/disk/mpt/mpt_raid.c
+++ b/sys/dev/disk/mpt/mpt_raid.c
@@ -283,7 +283,12 @@
 	error = mpt_spawn_raid_thread(mpt);
 	if (error != 0) {
 		mpt_prt(mpt, "Unable to spawn RAID thread!\n");
-		goto cleanup;
+		/*
+		 * Nothing to unwind yet: MPT_LOCK is not held, no CCB was
+		 * allocated, no handler was registered.  Falling through
+		 * to cleanup would MPT_UNLOCK an unheld lock and panic.
+		 */
+		return (error);
 	}
 	csa = &xpt_alloc_ccb()->csa;
 
@@ -312,6 +312,7 @@
 	mpt_raid_sysctl_attach(mpt);
 	return (0);
 cleanup:
+	xpt_free_ccb(&csa->ccb_h);	/* only reached after csa was allocated */
 	MPT_UNLOCK(mpt);
 	mpt_raid_detach(mpt);
 	return (error);