netdev - Re: [PATCH net-next v2 2/2] net: openvswitch: make masks cache size configurable

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Date:   Thu, 23 Jul 2020 09:42:36 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Eelco Chaudron <echaudro@...hat.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, dev@...nvswitch.org,
        pabeni@...hat.com, pshelar@....org, fw@...len.de
Subject: Re: [PATCH net-next v2 2/2] net: openvswitch: make masks cache size
 configurable

On Thu, 23 Jul 2020 14:58:31 +0200 Eelco Chaudron wrote:
> +	if ((size & (size - 1)) != 0 ||

is_power_of_2() ?

> +	    (size * sizeof(struct mask_cache_entry)) > PCPU_MIN_UNIT_SIZE)
> +		return NULL;

> +	new->cache_size = size;
> +	if (new->cache_size > 0) {
> +		cache = __alloc_percpu(sizeof(struct mask_cache_entry) *
> +				       new->cache_size,

array_size() ?

> +				       __alignof__(struct mask_cache_entry));
> +

No need for the new line here

> +		if (!cache) {
> +			kfree(new);
> +			return NULL;
> +		}
> +	}

> +	if (size == mc->cache_size || (size & (size - 1)) != 0)

why check "is power of 2" twice?

> @@ -454,7 +516,7 @@ void ovs_flow_tbl_destroy(struct flow_table *table)
>  	struct table_instance *ti = rcu_dereference_raw(table->ti);
>  	struct table_instance *ufid_ti = rcu_dereference_raw(table->ufid_ti);
>  
> -	free_percpu(table->mask_cache);
> +	call_rcu(&table->mask_cache->rcu, mask_cache_rcu_cb);
>  	call_rcu(&table->mask_array->rcu, mask_array_rcu_cb);
>  	table_instance_destroy(table, ti, ufid_ti, false);
>  }

This adds a new warning :(

net/openvswitch/flow_table.c:519:24: warning: incorrect type in argument 1 (different address spaces)
net/openvswitch/flow_table.c:519:24:    expected struct callback_head *head
net/openvswitch/flow_table.c:519:24:    got struct callback_head [noderef] __rcu *