net: sfc: Correct key_len for efx_tc_ct_zone_ht_params

BugLink: https://bugs.launchpad.net/bugs/2106632

[ Upstream commit a8620de72e5676993ec3a3b975f7c10908f5f60f ]

In efx_tc_ct_zone_ht_params, the key_len was previously set to
offsetof(struct efx_tc_ct_zone, linkage). This calculation is incorrect
because it includes any padding between the zone field and the linkage
field due to structure alignment, which can vary between systems.

This patch updates key_len to use sizeof_field(struct efx_tc_ct_zone, zone)
, ensuring that the hash table correctly uses the zone as the key. This fix
prevents potential hash lookup errors and improves connection tracking
reliability.

Fixes: c3bb5c6 ("sfc: functions to register for conntrack zone offload")
Signed-off-by: Liang Jie <liangjie@lixiang.com>
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Link: https://patch.msgid.link/20241230093709.3226854-1-buaajxlj@163.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Mehmet Basaran <mehmet.basaran@canonical.com>

Author: Liang Jie

drivers/net/ethernet/sfc/tc_conntrack.c

@@ -16,7 +16,7 @@ static int efx_tc_flow_block(enum tc_setup_type type, void *type_data,
 			     void *cb_priv);
 
 static const struct rhashtable_params efx_tc_ct_zone_ht_params = {
-	.key_len	= offsetof(struct efx_tc_ct_zone, linkage),
+	.key_len	= sizeof_field(struct efx_tc_ct_zone, zone),
 	.key_offset	= 0,
 	.head_offset	= offsetof(struct efx_tc_ct_zone, linkage),
 };