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net/mlx5e: CT, Avoid false lock dependency warning

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To avoid false lock dependency warning set the ct_entries_ht lock
class different than the lock class of the ht being used when deleting
last flow from a group and then deleting a group, we get into del_sw_flow_group()
which call rhashtable_destroy on fg->ftes_hash which will take ht->mutex but
it's different than the ht->mutex here.

======================================================
WARNING: possible circular locking dependency detected
5.10.0-rc2+ #8 Tainted: G           O
------------------------------------------------------
revalidator23/24009 is trying to acquire lock:
ffff888128d83828 (&node->lock){++++}-{3:3}, at: mlx5_del_flow_rules+0x83/0x7a0 [mlx5_core]

but task is already holding lock:
ffff8881081ef518 (&ht->mutex){+.+.}-{3:3}, at: rhashtable_free_and_destroy+0x37/0x720

which lock already depends on the new lock.

Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Paul Blakey <paulb@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
This commit is contained in:
Roi Dayan 2020-11-19 14:20:44 +02:00 committed by Saeed Mahameed
parent fe06992b04
commit 76e68d950a
1 changed files with 10 additions and 0 deletions
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10
drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
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@ -1539,6 +1539,14 @@ mlx5_tc_ct_free_pre_ct_tables(struct mlx5_ct_ft *ft)
mlx5_tc_ct_free_pre_ct(ft, &ft->pre_ct);
}
/* To avoid false lock dependency warning set the ct_entries_ht lock
* class different than the lock class of the ht being used when deleting
* last flow from a group and then deleting a group, we get into del_sw_flow_group()
* which call rhashtable_destroy on fg->ftes_hash which will take ht->mutex but
* it's different than the ht->mutex here.
*/
static struct lock_class_key ct_entries_ht_lock_key;
static struct mlx5_ct_ft *
mlx5_tc_ct_add_ft_cb(struct mlx5_tc_ct_priv *ct_priv, u16 zone,
struct nf_flowtable *nf_ft)
@ -1573,6 +1581,8 @@ mlx5_tc_ct_add_ft_cb(struct mlx5_tc_ct_priv *ct_priv, u16 zone,
if (err)
goto err_init;
lockdep_set_class(&ft->ct_entries_ht.mutex, &ct_entries_ht_lock_key);
err = rhashtable_insert_fast(&ct_priv->zone_ht, &ft->node,
zone_params);
if (err)