path: root/lib
diff options
authorDmitriy Vyukov <dvyukov@google.com>2015-09-22 10:51:52 +0200
committerDavid S. Miller <davem@davemloft.net>2015-09-22 17:36:07 -0700
commit7def0f952eccdd0edb3c504f4dab35ee0d3aba1f (patch)
treeb07b5d821064709d15bf725818ab3e3a751daafe /lib
parent23eedbc2435ddd226717603c4f3c8efec7bdbb4d (diff)
lib: fix data race in rhashtable_rehash_one
rhashtable_rehash_one() uses complex logic to update entry->next field, after INIT_RHT_NULLS_HEAD and NULLS_MARKER expansion: entry->next = 1 | ((base + off) << 1) This can be compiled along the lines of: entry->next = base + off entry->next <<= 1 entry->next |= 1 Which will break concurrent readers. NULLS value recomputation is not needed here, so just remove the complex logic. The data race was found with KernelThreadSanitizer (KTSAN). Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Thomas Graf <tgraf@suug.ch> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'lib')
1 files changed, 1 insertions, 4 deletions
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index cc0c69710dcf..a54ff8949f91 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -187,10 +187,7 @@ static int rhashtable_rehash_one(struct rhashtable *ht, unsigned int old_hash)
head = rht_dereference_bucket(new_tbl->buckets[new_hash],
new_tbl, new_hash);
- if (rht_is_a_nulls(head))
- INIT_RHT_NULLS_HEAD(entry->next, ht, new_hash);
- else
- RCU_INIT_POINTER(entry->next, head);
+ RCU_INIT_POINTER(entry->next, head);
rcu_assign_pointer(new_tbl->buckets[new_hash], entry);