rhashtable: use get_random_u32 for hash_rnd

This is much faster and just as secure. It also has the added benefit of
probably returning better randomness at early-boot on systems with
architectural RNGs.

Signed-off-by: Jason A. Donenfeld <[email protected]>
Cc: Thomas Graf <[email protected]>
Cc: Herbert Xu <[email protected]>
Signed-off-by: Theodore Ts'o <[email protected]>

Author: zx2c4

lib/rhashtable.c

@@ -235,7 +235,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
 
 	INIT_LIST_HEAD(&tbl->walkers);
 
-	get_random_bytes(&tbl->hash_rnd, sizeof(tbl->hash_rnd));
+	tbl->hash_rnd = get_random_u32();
 
 	for (i = 0; i < nbuckets; i++)
 		INIT_RHT_NULLS_HEAD(tbl->buckets[i], ht, i);