libbpf: Use IS_ERR_OR_NULL() in hashmap__free()

hashmap__new() uses ERR_PTR() to return an error so it's better to
use IS_ERR_OR_NULL() in order to check the pointer before calling
free(). This will prevent freeing an invalid pointer if somebody calls
hashmap__free() with the result of a failed hashmap__new() call.

Signed-off-by: Mauricio Vásquez <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Song Liu <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

tools/lib/bpf/hashmap.c

@@ -75,7 +75,7 @@ void hashmap__clear(struct hashmap *map)
 
 void hashmap__free(struct hashmap *map)
 {
-	if (!map)
+	if (IS_ERR_OR_NULL(map))
 		return;
 
 	hashmap__clear(map);
@@ -238,4 +238,3 @@ bool hashmap__delete(struct hashmap *map, const void *key,
 
 	return true;
 }
-