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Date: Thu, 16 Feb 2023 19:15:13 +0200
From: Vlad Buslov <vladbu@...dia.com>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
CC: Saeed Mahameed <saeed@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Eric Dumazet <edumazet@...gle.com>,
Saeed Mahameed <saeedm@...dia.com>, <netdev@...r.kernel.org>,
Tariq Toukan <tariqt@...dia.com>, Oz Shlomo <ozsh@...dia.com>,
Paul Blakey <paulb@...dia.com>
Subject: Re: [net-next 5/9] net/mlx5e: Implement CT entry update
On Thu 16 Feb 2023 at 16:51, Maciej Fijalkowski <maciej.fijalkowski@...el.com> wrote:
> On Wed, Feb 15, 2023 at 04:09:14PM -0800, Saeed Mahameed wrote:
>> From: Vlad Buslov <vladbu@...dia.com>
>>
>> With support for UDP NEW offload the flow_table may now send updates for
>> existing flows. Support properly replacing existing entries by updating
>> flow restore_cookie and replacing the rule with new one with the same match
>> but new mod_hdr action that sets updated ctinfo.
>>
>> Signed-off-by: Vlad Buslov <vladbu@...dia.com>
>> Reviewed-by: Oz Shlomo <ozsh@...dia.com>
>> Reviewed-by: Paul Blakey <paulb@...dia.com>
>> Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
>> ---
>> .../ethernet/mellanox/mlx5/core/en/tc_ct.c | 118 +++++++++++++++++-
>> 1 file changed, 117 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c b/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
>> index 193562c14c44..76e86f83b6ac 100644
>> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
>> @@ -871,6 +871,68 @@ mlx5_tc_ct_entry_add_rule(struct mlx5_tc_ct_priv *ct_priv,
>> return err;
>> }
>>
>> +static int
>> +mlx5_tc_ct_entry_replace_rule(struct mlx5_tc_ct_priv *ct_priv,
>> + struct flow_rule *flow_rule,
>> + struct mlx5_ct_entry *entry,
>> + bool nat, u8 zone_restore_id)
>> +{
>> + struct mlx5_ct_zone_rule *zone_rule = &entry->zone_rules[nat];
>> + struct mlx5_flow_attr *attr = zone_rule->attr, *old_attr;
>> + struct mlx5e_mod_hdr_handle *mh;
>> + struct mlx5_ct_fs_rule *rule;
>> + struct mlx5_flow_spec *spec;
>> + int err;
>> +
>> + spec = kvzalloc(sizeof(*spec), GFP_KERNEL);
>> + if (!spec)
>> + return -ENOMEM;
>> +
>> + old_attr = mlx5_alloc_flow_attr(ct_priv->ns_type);
>> + if (!attr) {
>
> when can attr == NULL? maybe check it in the first place before allocing
> spec above?
Should verify 'old_attr', not 'attr'. Thanks for catching this!
>
>> + err = -ENOMEM;
>> + goto err_attr;
>> + }
>> + *old_attr = *attr;
>> +
>> + err = mlx5_tc_ct_entry_create_mod_hdr(ct_priv, attr, flow_rule, &mh, zone_restore_id,
>> + nat, mlx5_tc_ct_entry_has_nat(entry));
>> + if (err) {
>> + ct_dbg("Failed to create ct entry mod hdr");
>> + goto err_mod_hdr;
>> + }
>> +
>> + mlx5_tc_ct_set_tuple_match(ct_priv, spec, flow_rule);
>> + mlx5e_tc_match_to_reg_match(spec, ZONE_TO_REG, entry->tuple.zone, MLX5_CT_ZONE_MASK);
>> +
>> + rule = ct_priv->fs_ops->ct_rule_add(ct_priv->fs, spec, attr, flow_rule);
>> + if (IS_ERR(rule)) {
>> + err = PTR_ERR(rule);
>> + ct_dbg("Failed to add replacement ct entry rule, nat: %d", nat);
>> + goto err_rule;
>> + }
>> +
>> + ct_priv->fs_ops->ct_rule_del(ct_priv->fs, zone_rule->rule);
>> + zone_rule->rule = rule;
>> + mlx5_tc_ct_entry_destroy_mod_hdr(ct_priv, old_attr, zone_rule->mh);
>> + zone_rule->mh = mh;
>> +
>> + kfree(old_attr);
>> + kvfree(spec);
>
> not a big deal but you could make a common goto below with a different
> name
You mean jump from here to the middle of the error handling code below
in order not to duplicate these two calls to *free()? Honestly, I would
much rather prefer _not_ to do that since goto is necessary evil for
error handling in C but I don't believe we should handle any common
non-error code paths with it and it is not typically done in mlx5.
>
>> + ct_dbg("Replaced ct entry rule in zone %d", entry->tuple.zone);
>> +
>> + return 0;
>> +
>> +err_rule:
>> + mlx5_tc_ct_entry_destroy_mod_hdr(ct_priv, zone_rule->attr, mh);
>> + mlx5_put_label_mapping(ct_priv, attr->ct_attr.ct_labels_id);
>> +err_mod_hdr:
>> + kfree(old_attr);
>> +err_attr:
>> + kvfree(spec);
>> + return err;
>> +}
>> +
>> static bool
>> mlx5_tc_ct_entry_valid(struct mlx5_ct_entry *entry)
>> {
>> @@ -1065,6 +1127,52 @@ mlx5_tc_ct_entry_add_rules(struct mlx5_tc_ct_priv *ct_priv,
>> return err;
>> }
>>
>> +static int
>> +mlx5_tc_ct_entry_replace_rules(struct mlx5_tc_ct_priv *ct_priv,
>> + struct flow_rule *flow_rule,
>> + struct mlx5_ct_entry *entry,
>> + u8 zone_restore_id)
>> +{
>> + int err;
>> +
>> + err = mlx5_tc_ct_entry_replace_rule(ct_priv, flow_rule, entry, false,
>
> would it make sense to replace the bool nat in here with some kind of
> enum?
It is either nat rule or non-nat rule. Why would we invent an enum here?
Moreover, boolean 'nat' is already used in multiple places in this file,
so this patch just re-uses existing convention.
>
>> + zone_restore_id);
>> + if (err)
>> + return err;
>> +
>> + err = mlx5_tc_ct_entry_replace_rule(ct_priv, flow_rule, entry, true,
>> + zone_restore_id);
>> + if (err)
>> + mlx5_tc_ct_entry_del_rule(ct_priv, entry, false);
>> + return err;
>> +}
>> +
>> +static int
>> +mlx5_tc_ct_block_flow_offload_replace(struct mlx5_ct_ft *ft, struct flow_rule *flow_rule,
>> + struct mlx5_ct_entry *entry, unsigned long cookie)
>> +{
>> + struct mlx5_tc_ct_priv *ct_priv = ft->ct_priv;
>> + int err;
>> +
>> + err = mlx5_tc_ct_entry_replace_rules(ct_priv, flow_rule, entry, ft->zone_restore_id);
>> + if (!err)
>> + return 0;
>> +
>> + /* If failed to update the entry, then look it up again under ht_lock
>> + * protection and properly delete it.
>> + */
>> + spin_lock_bh(&ct_priv->ht_lock);
>> + entry = rhashtable_lookup_fast(&ft->ct_entries_ht, &cookie, cts_ht_params);
>> + if (entry) {
>> + rhashtable_remove_fast(&ft->ct_entries_ht, &entry->node, cts_ht_params);
>> + spin_unlock_bh(&ct_priv->ht_lock);
>> + mlx5_tc_ct_entry_put(entry);
>> + } else {
>> + spin_unlock_bh(&ct_priv->ht_lock);
>> + }
>> + return err;
>> +}
>> +
>> static int
>> mlx5_tc_ct_block_flow_offload_add(struct mlx5_ct_ft *ft,
>> struct flow_cls_offload *flow)
>> @@ -1087,9 +1195,17 @@ mlx5_tc_ct_block_flow_offload_add(struct mlx5_ct_ft *ft,
>> spin_lock_bh(&ct_priv->ht_lock);
>> entry = rhashtable_lookup_fast(&ft->ct_entries_ht, &cookie, cts_ht_params);
>> if (entry && refcount_inc_not_zero(&entry->refcnt)) {
>> + if (entry->restore_cookie == meta_action->ct_metadata.cookie) {
>> + spin_unlock_bh(&ct_priv->ht_lock);
>> + mlx5_tc_ct_entry_put(entry);
>> + return -EEXIST;
>> + }
>> + entry->restore_cookie = meta_action->ct_metadata.cookie;
>> spin_unlock_bh(&ct_priv->ht_lock);
>> +
>> + err = mlx5_tc_ct_block_flow_offload_replace(ft, flow_rule, entry, cookie);
>> mlx5_tc_ct_entry_put(entry);
>
> in case of err != 0, haven't you already put the entry inside
> mlx5_tc_ct_block_flow_offload_replace() ?
No. Here we release the reference that was obtained 10 lines up and
mlx5_tc_ct_block_flow_offload_replace() releases the reference held by
ct_entries_ht table.
>
>> - return -EEXIST;
>> + return err;
>> }
>> spin_unlock_bh(&ct_priv->ht_lock);
>>
>> --
>> 2.39.1
>>
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