From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ferruh Yigit <ferruh.yigit@intel.com>
Subject: Re: [PATCH v6 3/3] net/tap: allow secondary process to
 access primary device queues
Date: Thu, 11 Oct 2018 17:32:31 +0100
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References: <1539182356-15496-1-git-send-email-rasland@mellanox.com>
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Cc: Thomas Monjalon <thomas@monjalon.net>, "dev@dpdk.org" <dev@dpdk.org>,
 Shahaf Shuler <shahafs@mellanox.com>, Ori Kam <orika@mellanox.com>
To: Raslan Darawsheh <rasland@mellanox.com>,
 "keith.wiles@intel.com" <keith.wiles@intel.com>
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On 10/10/2018 3:39 PM, Raslan Darawsheh wrote:
> @@ -2082,6 +2214,14 @@ rte_pmd_tap_probe(struct rte_vdev_device *dev)
>  	TAP_LOG(NOTICE, "Initializing pmd_tap for %s as %s",
>  		name, tap_name);
>  
> +	/* Register IPC feed callback */
> +	ret = rte_mp_action_register(TAP_MP_KEY, tap_mp_sync_queues);
> +	if (ret < 0 && rte_errno != EEXIST && tap_devices_count) {
> +		TAP_LOG(ERR, "%s: Failed to register IPC callback: %s",
> +			tuntap_name, strerror(rte_errno));
> +		goto leave;
> +	}
> +	tap_devices_count++;
>  	ret = eth_dev_tap_create(dev, tap_name, remote_iface, &user_mac,
>  		ETH_TUNTAP_TYPE_TAP);

Why not rely on "tap_devices_count" but call rte_mp_action_register() every time
and try to figure out status from ret?

if (tap_devices_count == 0) {
  ret = rte_mp_action_register(TAP_MP_KEY, tap_mp_sync_queues);
  if (ret < 0) {
    TAP_LOG();
    goto leave;
  }
}
tap_devices_count++;