Re: [dpdk-dev] [PATCH v3 1/2] net/tap: change queue fd to be pointers to process private

["Wiles, Keith" <keith.wiles@intel.com>]

> On Sep 27, 2018, at 6:19 AM, Raslan Darawsheh <rasland@mellanox.com> wrote:
> 
> change the fds for the queues to be pointers and add new process private
> structure and make the queue fds point to it.
> 
> Signed-off-by: Raslan Darawsheh <rasland@mellanox.com>
> ---
> drivers/net/tap/rte_eth_tap.c | 63 ++++++++++++++++++++++++-------------------
> drivers/net/tap/rte_eth_tap.h |  9 +++++--
> drivers/net/tap/tap_intr.c    |  4 +--
> 3 files changed, 44 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
> index ad5ae98..8cc4552 100644
> --- a/drivers/net/tap/rte_eth_tap.c
> +++ b/drivers/net/tap/rte_eth_tap.c
> @@ -64,6 +64,7 @@
> 
> static struct rte_vdev_driver pmd_tap_drv;
> static struct rte_vdev_driver pmd_tun_drv;
> +static struct pmd_process_private *process_private;

Maybe I do not see some minor point for making fd a pointer to fd when we could have an array of process_private[RTE_PMD_TAP_MAX_QUEUES] instead of a pointer type here. Then we do not need to allocate the memory each PMD and they would still have a private copy. Remove the array of rx/tx fds in the structure. This way it appears we can remove the code below that is making fd a pointer to fd. It just seems overly complex to me at the cost of a few more bytes of memory.

This would remove int fd; from the structure and add a pointer to the pid_process_private instead, which is private by default.

Did I miss some detail here that makes my comment wrong?

> 
> static const char *valid_arguments[] = {
> 	ETH_TAP_IFACE_ARG,
> @@ -331,7 +332,7 @@ pmd_rx_burst(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
> 		uint16_t data_off = rte_pktmbuf_headroom(mbuf);
> 		int len;
> 
> -		len = readv(rxq->fd, *rxq->iovecs,
> +		len = readv(*rxq->fd, *rxq->iovecs,
> 			    1 +
> 			    (rxq->rxmode->offloads & DEV_RX_OFFLOAD_SCATTER ?
> 			     rxq->nb_rx_desc : 1));
> @@ -595,7 +596,7 @@ tap_write_mbufs(struct tx_queue *txq, uint16_t num_mbufs,
> 			tap_tx_l4_cksum(l4_cksum, l4_phdr_cksum, l4_raw_cksum);
> 
> 		/* copy the tx frame data */
> -		n = writev(txq->fd, iovecs, j);
> +		n = writev(*txq->fd, iovecs, j);
> 		if (n <= 0)
> 			break;
> 		(*num_packets)++;
> @@ -976,13 +977,13 @@ tap_dev_close(struct rte_eth_dev *dev)
> 	tap_flow_implicit_flush(internals, NULL);
> 
> 	for (i = 0; i < RTE_PMD_TAP_MAX_QUEUES; i++) {
> -		if (internals->rxq[i].fd != -1) {
> -			close(internals->rxq[i].fd);
> -			internals->rxq[i].fd = -1;
> +		if (*internals->rxq[i].fd != -1) {
> +			close(*internals->rxq[i].fd);
> +			*internals->rxq[i].fd = -1;
> 		}
> -		if (internals->txq[i].fd != -1) {
> -			close(internals->txq[i].fd);
> -			internals->txq[i].fd = -1;
> +		if (*internals->txq[i].fd != -1) {
> +			close(*internals->txq[i].fd);
> +			*internals->txq[i].fd = -1;
> 		}
> 	}
> 
> @@ -1007,9 +1008,9 @@ tap_rx_queue_release(void *queue)
> {
> 	struct rx_queue *rxq = queue;
> 
> -	if (rxq && (rxq->fd > 0)) {
> -		close(rxq->fd);
> -		rxq->fd = -1;
> +	if (rxq && rxq->fd && (*rxq->fd > 0)) {
> +		close(*rxq->fd);
> +		*rxq->fd = -1;
> 		rte_pktmbuf_free(rxq->pool);
> 		rte_free(rxq->iovecs);
> 		rxq->pool = NULL;
> @@ -1022,9 +1023,9 @@ tap_tx_queue_release(void *queue)
> {
> 	struct tx_queue *txq = queue;
> 
> -	if (txq && (txq->fd > 0)) {
> -		close(txq->fd);
> -		txq->fd = -1;
> +	if (txq && txq->fd && (*txq->fd > 0)) {
> +		close(*txq->fd);
> +		*txq->fd = -1;
> 	}
> }
> 
> @@ -1214,13 +1215,13 @@ tap_setup_queue(struct rte_eth_dev *dev,
> 	struct rte_gso_ctx *gso_ctx;
> 
> 	if (is_rx) {
> -		fd = &rx->fd;
> -		other_fd = &tx->fd;
> +		fd = rx->fd;
> +		other_fd = tx->fd;
> 		dir = "rx";
> 		gso_ctx = NULL;
> 	} else {
> -		fd = &tx->fd;
> -		other_fd = &rx->fd;
> +		fd = tx->fd;
> +		other_fd = rx->fd;
> 		dir = "tx";
> 		gso_ctx = &tx->gso_ctx;
> 	}
> @@ -1331,7 +1332,7 @@ tap_rx_queue_setup(struct rte_eth_dev *dev,
> 	}
> 
> 	TAP_LOG(DEBUG, "  RX TUNTAP device name %s, qid %d on fd %d",
> -		internals->name, rx_queue_id, internals->rxq[rx_queue_id].fd);
> +		internals->name, rx_queue_id, *internals->rxq[rx_queue_id].fd);
> 
> 	return 0;
> 
> @@ -1371,7 +1372,7 @@ tap_tx_queue_setup(struct rte_eth_dev *dev,
> 		return -1;
> 	TAP_LOG(DEBUG,
> 		"  TX TUNTAP device name %s, qid %d on fd %d csum %s",
> -		internals->name, tx_queue_id, internals->txq[tx_queue_id].fd,
> +		internals->name, tx_queue_id, *internals->txq[tx_queue_id].fd,
> 		txq->csum ? "on" : "off");
> 
> 	return 0;
> @@ -1633,6 +1634,10 @@ eth_dev_tap_create(struct rte_vdev_device *vdev, char *tap_name,
> 		goto error_exit_nodev;
> 	}
> 
> +	process_private = (struct pmd_process_private *)
> +		rte_zmalloc_socket(tap_name, sizeof(struct pmd_process_private),
> +			RTE_CACHE_LINE_SIZE, dev->device->numa_node);
> +
> 	pmd = dev->data->dev_private;
> 	pmd->dev = dev;
> 	snprintf(pmd->name, sizeof(pmd->name), "%s", tap_name);
> @@ -1669,8 +1674,10 @@ eth_dev_tap_create(struct rte_vdev_device *vdev, char *tap_name,
> 	/* 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;
> +		process_private->rxq_fds[i] = -1;
> +		process_private->txq_fds[i] = -1;
> +		pmd->rxq[i].fd = &process_private->rxq_fds[i];
> +		pmd->txq[i].fd = &process_private->txq_fds[i];
> 	}
> 
> 	if (pmd->type == ETH_TUNTAP_TYPE_TAP) {
> @@ -2089,13 +2096,13 @@ rte_pmd_tap_remove(struct rte_vdev_device *dev)
> 		tap_nl_final(internals->nlsk_fd);
> 	}
> 	for (i = 0; i < RTE_PMD_TAP_MAX_QUEUES; i++) {
> -		if (internals->rxq[i].fd != -1) {
> -			close(internals->rxq[i].fd);
> -			internals->rxq[i].fd = -1;
> +		if (*internals->rxq[i].fd != -1) {
> +			close(*internals->rxq[i].fd);
> +			*internals->rxq[i].fd = -1;
> 		}
> -		if (internals->txq[i].fd != -1) {
> -			close(internals->txq[i].fd);
> -			internals->txq[i].fd = -1;
> +		if (*internals->txq[i].fd != -1) {
> +			close(*internals->txq[i].fd);
> +			*internals->txq[i].fd = -1;
> 		}
> 	}
> 
> diff --git a/drivers/net/tap/rte_eth_tap.h b/drivers/net/tap/rte_eth_tap.h
> index 44e2773..4146f5c 100644
> --- a/drivers/net/tap/rte_eth_tap.h
> +++ b/drivers/net/tap/rte_eth_tap.h
> @@ -46,7 +46,7 @@ struct rx_queue {
> 	struct rte_mempool *mp;         /* Mempool for RX packets */
> 	uint32_t trigger_seen;          /* Last seen Rx trigger value */
> 	uint16_t in_port;               /* Port ID */
> -	int fd;
> +	int *fd;
> 	struct pkt_stats stats;         /* Stats for this RX queue */
> 	uint16_t nb_rx_desc;            /* max number of mbufs available */
> 	struct rte_eth_rxmode *rxmode;  /* RX features */
> @@ -56,7 +56,7 @@ struct rx_queue {
> };
> 
> struct tx_queue {
> -	int fd;
> +	int *fd;
> 	int type;                       /* Type field - TUN|TAP */
> 	uint16_t *mtu;                  /* Pointer to MTU from dev_data */
> 	uint16_t csum:1;                /* Enable checksum offloading */
> @@ -92,6 +92,11 @@ struct pmd_internals {
> 	int ka_fd;                        /* keep-alive file descriptor */
> };
> 
> +struct pmd_process_private {
> +	int rxq_fds[RTE_PMD_TAP_MAX_QUEUES];
> +	int txq_fds[RTE_PMD_TAP_MAX_QUEUES];
> +};
> +
> /* tap_intr.c */
> 
> int tap_rx_intr_vec_set(struct rte_eth_dev *dev, int set);
> diff --git a/drivers/net/tap/tap_intr.c b/drivers/net/tap/tap_intr.c
> index fc59018..a4b212d 100644
> --- a/drivers/net/tap/tap_intr.c
> +++ b/drivers/net/tap/tap_intr.c
> @@ -71,7 +71,7 @@ tap_rx_intr_vec_install(struct rte_eth_dev *dev)
> 		struct rx_queue *rxq = pmd->dev->data->rx_queues[i];
> 
> 		/* Skip queues that cannot request interrupts. */
> -		if (!rxq || rxq->fd <= 0) {
> +		if (!rxq || !rxq->fd || *rxq->fd <= 0) {
> 			/* Use invalid intr_vec[] index to disable entry. */
> 			intr_handle->intr_vec[i] =
> 				RTE_INTR_VEC_RXTX_OFFSET +
> @@ -79,7 +79,7 @@ tap_rx_intr_vec_install(struct rte_eth_dev *dev)
> 			continue;
> 		}
> 		intr_handle->intr_vec[i] = RTE_INTR_VEC_RXTX_OFFSET + count;
> -		intr_handle->efds[count] = rxq->fd;
> +		intr_handle->efds[count] = *rxq->fd;
> 		count++;
> 	}
> 	if (!count)
> -- 
> 2.7.4
> 

Regards,
Keith