[dpdk-dev] [PATCH v4] net/tap: fix device removal when no queues exist

[Varghese, Vipin]

Sure, shared a suggestion. If not required can drop the same.

> -----Original Message-----
> From: Wiles, Keith
> Sent: Wednesday, May 23, 2018 10:24 AM
> To: Varghese, Vipin <vipin.varghese at intel.com>
> Cc: Ophir Munk <ophirmu at mellanox.com>; dev at dpdk.org; Pascal Mazon
> <pascal.mazon at 6wind.com>; Thomas Monjalon <thomas at monjalon.net>;
> Olga Shern <olgas at mellanox.com>; Shahaf Shuler <shahafs at mellanox.com>;
> stable at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v4] net/tap: fix device removal when no queues
> exist
> 
> 
> 
> > On May 22, 2018, at 11:50 PM, Varghese, Vipin <vipin.varghese at intel.com>
> wrote:
> >
> > 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?
> 
> Why would we want to have a LOG DEBUG here, it would make the debug
> output a bit chatty IMO. I mean you could have one, but it seems ok as it is to
> me.
> 
> >
> >> +		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
> >
> 
> Regards,
> Keith