From: Igor Putovny <igor.putovny@nic.cz>
Date: Wed, 11 Jun 2025 15:44:38 +0000 (+0200)
Subject: Assert that hash table is not being modified during HASH_WALK
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fheads%2Fip-assert-hash-walk;p=thirdparty%2Fbird.git

Assert that hash table is not being modified during HASH_WALK

According to measurements of hash_test, hash table with this assertion added
was not found to be significantly slower than without it on average. Therefore
we conclude that this addition would not hamper the performance of HASH_WALK.
---

diff --git a/lib/hash.h b/lib/hash.h
index 3c173958f..4c05c6d7e 100644
--- a/lib/hash.h
+++ b/lib/hash.h
@@ -165,10 +165,11 @@
 #define HASH_WALK(v,next,n)						\
   do {									\
     HASH_TYPE(v) *n;							\
+    const uint _count = v.count;					\
     uint _i;								\
     uint _s = HASH_SIZE(v);						\
     for (_i = 0; _i < _s; _i++)						\
-      for (n = (v).data[_i]; n; n = n->next)
+      for (n = (v).data[_i]; ({ ASSERT_DIE(v.count == _count); }), n; n = n->next)
 
 #define HASH_WALK_END } while (0)