Willy Tarreau c564abd107 BUG/MAJOR: conn-idle: fix hash indexing issues on idle conns ...

Idle connections do not work on 32-bit machines due to an alignment issue
causing the connection nodes to be indexed with their lower 32-bits set to
zero and the higher 32 ones containing the 32 lower bitss of the hash. The
cause is the use of ebmb_node with an aligned data, as on this platform
ebmb_node is only 32-bit aligned, leaving a hole before the following hash
which is a uint64_t:

  $ pahole -C conn_hash_node ./haproxy
  struct conn_hash_node {
        struct ebmb_node           node;                 /*     0    20 */

        /* XXX 4 bytes hole, try to pack */

        int64_t                    hash;                 /*    24     8 */
        struct connection *        conn;                 /*    32     4 */

        /* size: 40, cachelines: 1, members: 3 */
        /* sum members: 32, holes: 1, sum holes: 4 */
        /* padding: 4 */
        /* last cacheline: 40 bytes */
  };

Instead, eb64 nodes should be used when it comes to simply storing a
64-bit key, and that is what this patch does.

For backports, a variant consisting in simply marking the "hash" member
with a "packed" attribute on the struct also does the job (tested), and
might be preferable if the fix is difficult to adapt. Only 2.6 and 2.5
are affected by this.

(cherry picked from commit 852234848241f61a976f8856123a34a3c19275ba)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>

2022-10-10 07:40:32 +02:00

..

haproxy

BUG/MAJOR: conn-idle: fix hash indexing issues on idle conns

2022-10-10 07:40:32 +02:00

import

MINOR: ebtree: add ebmb_lookup_shorter() to pursue lookups

2022-08-03 14:55:25 +02:00