netdev - Re: [PATCH rfc v2 02/10] net: dsa: qca8k: Move completion into DSA core

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Date:   Thu, 22 Sep 2022 18:59:23 +0000
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     netdev <netdev@...r.kernel.org>,
        "mattias.forsblad@...il.com" <mattias.forsblad@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Christian Marangi <ansuelsmth@...il.com>
Subject: Re: [PATCH rfc v2 02/10] net: dsa: qca8k: Move completion into DSA
 core

On Thu, Sep 22, 2022 at 07:58:13PM +0200, Andrew Lunn wrote:
> @@ -1528,7 +1516,7 @@ static void qca8k_mib_autocast_handler(struct dsa_switch *ds, struct sk_buff *sk
>  exit:
>  	/* Complete on receiving all the mib packet */
>  	if (refcount_dec_and_test(&mib_eth_data->port_parsed))
> -		complete(&mib_eth_data->rw_done);
> +		dsa_inband_complete(&mib_eth_data->inband);
>  }
>  
>  static int
> @@ -1543,8 +1531,6 @@ qca8k_get_ethtool_stats_eth(struct dsa_switch *ds, int port, u64 *data)
>  
>  	mutex_lock(&mib_eth_data->mutex);
>  
> -	reinit_completion(&mib_eth_data->rw_done);
> -
>  	mib_eth_data->req_port = dp->index;
>  	mib_eth_data->data = data;
>  	refcount_set(&mib_eth_data->port_parsed, QCA8K_NUM_PORTS);
> @@ -1562,7 +1548,8 @@ qca8k_get_ethtool_stats_eth(struct dsa_switch *ds, int port, u64 *data)
>  	if (ret)
>  		goto exit;
>  
> -	ret = wait_for_completion_timeout(&mib_eth_data->rw_done, QCA8K_ETHERNET_TIMEOUT);
> +	ret = dsa_inband_wait_for_completion(&mib_eth_data->inband,
> +					     QCA8K_ETHERNET_TIMEOUT);

Doesn't the reinit_completion from qca8k_get_ethtool_stats_eth() still
race with qca8k_mib_autocast_handler()? From the comments, it appears to
me that the regmap_update_bits() call is what triggers a MIB autocast,
and so, reinit_completion() needs to be before that.