Re: [PATCH v4] net/tap: fix device removal when no queues exist

["Varghese, Vipin" <vipin.varghese@intel.com>]

Hi Ophir,

One suggestion shared inline to email

<Snipped>

> 
> diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c index
> c006d07..52ef799 100644
> --- a/drivers/net/tap/rte_eth_tap.c
> +++ b/drivers/net/tap/rte_eth_tap.c
> @@ -929,6 +929,15 @@ tap_dev_close(struct rte_eth_dev *dev)
>  		ioctl(internals->ioctl_sock, SIOCSIFFLAGS,
>  				&internals->remote_initial_flags);
>  	}
> +
> +	if (internals->ka_fd != -1) {
> +		close(internals->ka_fd);

Do we need to notify the user which fd is been closed via LOG DEBUG?

> +		internals->ka_fd = -1;
> +	}
> +	/*
> +	 * Since TUN device has no more opened file descriptors
> +	 * it will be removed from kernel
> +	 */
>  }
> 
>  static void
> @@ -1549,6 +1558,7 @@ eth_dev_tap_create(struct rte_vdev_device *vdev,
> char *tap_name,
>  	dev->intr_handle = &pmd->intr_handle;
> 
>  	/* Presetup the fds to -1 as being not valid */
> +	pmd->ka_fd = -1;
>  	for (i = 0; i < RTE_PMD_TAP_MAX_QUEUES; i++) {
>  		pmd->rxq[i].fd = -1;
>  		pmd->txq[i].fd = -1;
> @@ -1561,13 +1571,17 @@ eth_dev_tap_create(struct rte_vdev_device *vdev,
> char *tap_name,
>  			rte_memcpy(&pmd->eth_addr, mac_addr,
> sizeof(*mac_addr));
>  	}
> 
> -	/* Immediately create the netdevice (this will create the 1st queue). */
> -	/* rx queue */
> -	if (tap_setup_queue(dev, pmd, 0, 1) == -1)
> -		goto error_exit;
> -	/* tx queue */
> -	if (tap_setup_queue(dev, pmd, 0, 0) == -1)
> +	/*
> +	 * Allocate a TUN device keep-alive file descriptor that will only be
> +	 * closed when the TUN device itself is closed or removed.
> +	 * This keep-alive file descriptor will guarantee that the TUN device
> +	 * exists even when all of its queues are closed
> +	 */
> +	pmd->ka_fd = tun_alloc(pmd);
> +	if (pmd->ka_fd == -1) {
> +		TAP_LOG(ERR, "Unable to create %s interface", tuntap_name);
>  		goto error_exit;
> +	}
> 
>  	ifr.ifr_mtu = dev->data->mtu;
>  	if (tap_ioctl(pmd, SIOCSIFMTU, &ifr, 1, LOCAL_AND_REMOTE) < 0) @@
> -1961,9 +1975,12 @@ rte_pmd_tap_remove(struct rte_vdev_device *dev)
> 
>  	close(internals->ioctl_sock);
>  	rte_free(eth_dev->data->dev_private);
> -
>  	rte_eth_dev_release_port(eth_dev);
> 
> +	if (internals->ka_fd != -1) {
> +		close(internals->ka_fd);
> +		internals->ka_fd = -1;
> +	}
>  	return 0;
>  }
> 
> diff --git a/drivers/net/tap/rte_eth_tap.h b/drivers/net/tap/rte_eth_tap.h index
> babe42d..575dce4 100644
> --- a/drivers/net/tap/rte_eth_tap.h
> +++ b/drivers/net/tap/rte_eth_tap.h
> @@ -81,6 +81,7 @@ struct pmd_internals {
>  	struct rx_queue rxq[RTE_PMD_TAP_MAX_QUEUES]; /* List of RX
> queues */
>  	struct tx_queue txq[RTE_PMD_TAP_MAX_QUEUES]; /* List of TX queues
> */
>  	struct rte_intr_handle intr_handle;          /* LSC interrupt handle. */
> +	int ka_fd;                        /* keep-alive file descriptor */
>  };
> 
>  /* tap_intr.c */
> --
> 2.7.4