No, you may not /* FALLTHROUGH */. Not only will you return an incorrect

result, but you'd corrupt the kernel malloc() arena if it weren't for a
small but life-saving optimization in ioctl().

MFC after:	1 week

sys/fs/procfs/procfs_vnops.c

@@ -268,7 +268,7 @@ procfs_ioctl(ap)
 	  break;
 	case PIOCGFL:
 	  *(unsigned int*)ap->a_data = (unsigned int)procp->p_pfsflags;
-	  /* FALLTHROUGH */
+	  break;
 	case PIOCSTATUS:
 	  psp = (struct procfs_status *)ap->a_data;
 	  psp->state = (procp->p_step == 0);