openvswitch: conntrack: annotate ct limit hlist traversal

openvswitch: conntrack: annotate ct limit hlist traversal

ct_limit_set() is documented as being called with ovs_mutex held. It
walks the ct limit hlist with hlist_for_each_entry_rcu(), but the
iterator does not currently pass the OVS lockdep condition used
elsewhere for RCU-protected OVS objects.

Pass lockdep_ovsl_is_held() to the iterator. This matches the function's
existing caller contract and lets CONFIG_PROVE_RCU_LIST distinguish the
ovs_mutex-protected update path from the RCU read-side ct_limit_get()
path.

This was found by our static analysis tool and then manually reviewed
against the current tree. In the reviewed CONFIG_PROVE_RCU_LIST triage
run, the writer-side ct limit update produced the expected "RCU-list
traversed in non-reader section!!" warning while ovs_mutex was held,
with the stack matching ct_limit_set() and ovs_ct_limit_set_zone_limit().
The change is limited to documenting the existing protection contract.

This is a lockdep annotation cleanup. It does not change the conntrack
limit list update or release behavior.

Signed-off-by: Runyu Xiao <runyu.xiao@seu.edu.cn>
Reviewed-by: Eelco Chaudron <echaudro@redhat.com>
Link: https://patch.msgid.link/20260624150149.3510541-1-runyu.xiao@seu.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>