depmod: Support modules.order with duplicate lines

If the same line exists multiple times in modules.order, consider only
the first, since this is the earliest position requested.

This also makes sure that index iterator never turns positive or would
ever trigger a signed integer overflow.

Signed-off-by: Tobias Stoeckmann <[email protected]>
Reviewed-by: Emil Velikov <[email protected]>
Link: #158
Signed-off-by: Lucas De Marchi <[email protected]>

tools/depmod.c

@@ -1484,7 +1484,7 @@ static void depmod_modules_sort(struct depmod *depmod)
 		}
 		line[len - 1] = '\0';
 		mod = hash_find(depmod->modules_by_uncrelpath, line);
-		if (mod == NULL)
+		if (mod == NULL || mod->sort_idx < 0)
 			continue;
 		mod->sort_idx = i++;
 	}