Re: [PATCH] app/testpmd: skip stopped queues when forwarding

["Singh, Aman Deep" <aman.deep.singh@intel.com>]

Hi Dmitry,

Thanks for the patch.

On 1/13/2022 2:51 PM, Dmitry Kozlyuk wrote:
> After "port <port_id> rxq|txq <queue_id> stop"
> the stopped queue was used in forwarding nonetheless,
> which may cause undefined behavior in the PMD.
>
> Record the configured queue state
> and account for it when launching forwarding as follows:
> +--------+---------+-----------------+---------------+
> |RxQ     |TxQ      |Configured mode  |Launch routine |
> +--------+---------+-----------------+---------------+
> |stopped |stopped  |*                |-              |
> |stopped |started  |txonly           |(configured)   |
> |stopped |started  |*                |-              |
> |started |stopped  |*                |rxonly         |
> |started |started  |*                |(configured)   |
> +--------+---------+-----------------+---------------+
> Display stopped queues on "show port config rxtx".
>
> Fixes: 5f4ec54f1d16 ("testpmd: queue start and stop")
> Cc: jing.d.chen@intel.com
> Cc: stable@dpdk.org
>
> Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> Reviewed-by: Raslan Darawsheh <rasland@nvidia.com>
> ---
>   app/test-pmd/cmdline.c |  8 ++++++++
>   app/test-pmd/config.c  |  6 ++++++
>   app/test-pmd/testpmd.c | 18 ++++++++++++++++--
>   app/test-pmd/testpmd.h | 10 ++++++++++
>   4 files changed, 40 insertions(+), 2 deletions(-)
>
> diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c
> index e626b1c7d9..8b0920e23d 100644
> --- a/app/test-pmd/cmdline.c
> +++ b/app/test-pmd/cmdline.c
> @@ -2702,6 +2702,14 @@ cmd_config_rxtx_queue_parsed(void *parsed_result,
>   
>   	if (ret == -ENOTSUP)
>   		fprintf(stderr, "Function not supported in PMD\n");
> +	if (ret == 0) {
> +		struct rte_port *port;
> +		struct queue_state *states;
> +
> +		port = &ports[res->portid];
> +		states = isrx ? port->rxq_state : port->txq_state;
> +		states[res->qid].stopped = !isstart;
> +	}
>   }
>   
>   cmdline_parse_token_string_t cmd_config_rxtx_queue_port =
> diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
> index 1722d6c8f8..7ce9cb483a 100644
> --- a/app/test-pmd/config.c
> +++ b/app/test-pmd/config.c
> @@ -2817,6 +2817,9 @@ rxtx_config_display(void)
>   				       rx_conf->share_qid);
>   			printf("\n");
>   		}
> +		for (qid = 0; qid < nb_rxq; qid++)
> +			if (ports[pid].rxq_state[qid].stopped)
> +				printf("    RX queue %d is stopped\n", qid);
>   
>   		/* per tx queue config only for first queue to be less verbose */
>   		for (qid = 0; qid < 1; qid++) {
> @@ -2850,6 +2853,9 @@ rxtx_config_display(void)
>   			printf("      TX offloads=0x%"PRIx64" - TX RS bit threshold=%d\n",
>   				offloads_tmp, tx_rs_thresh_tmp);
>   		}
> +		for (qid = 0; qid < nb_txq; qid++)
> +			if (ports[pid].txq_state[qid].stopped)
> +				printf("    TX queue %d is stopped\n", qid);
>   	}
>   }
>   
> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
> index 6c387bde84..36ff845181 100644
> --- a/app/test-pmd/testpmd.c
> +++ b/app/test-pmd/testpmd.c
> @@ -2152,6 +2152,8 @@ flush_fwd_rx_queues(void)
>   		for (rxp = 0; rxp < cur_fwd_config.nb_fwd_ports; rxp++) {
>   			for (rxq = 0; rxq < nb_rxq; rxq++) {
>   				port_id = fwd_ports_ids[rxp];
> +				if (ports[port_id].rxq_state[rxq].stopped)
> +					continue;
>   				/**
>   				* testpmd can stuck in the below do while loop
>   				* if rte_eth_rx_burst() always returns nonzero
> @@ -2223,8 +2225,20 @@ run_pkt_fwd_on_lcore(struct fwd_lcore *fc, packet_fwd_t pkt_fwd)
>   static int
>   start_pkt_forward_on_core(void *fwd_arg)
>   {
> -	run_pkt_fwd_on_lcore((struct fwd_lcore *) fwd_arg,
> -			     cur_fwd_config.fwd_eng->packet_fwd);
> +	struct fwd_lcore *fc = fwd_arg;
> +	struct fwd_stream *fsm = fwd_streams[fc->stream_idx];
> +	struct queue_state *rxq = &ports[fsm->rx_port].rxq_state[fsm->rx_queue];
> +	struct queue_state *txq = &ports[fsm->tx_port].txq_state[fsm->tx_queue];
> +	struct fwd_engine *fwd_engine = cur_fwd_config.fwd_eng;
> +	packet_fwd_t packet_fwd;
> +
> +	/* Check if there will ever be any packets to send. */
> +	if (rxq->stopped && (txq->stopped || fwd_engine != &tx_only_engine))
> +		return 0;
> +	/* Force rxonly mode if RxQ is started, but TxQ is stopped. */
> +	packet_fwd = !rxq->stopped && txq->stopped ? rx_only_engine.packet_fwd
> +						   : fwd_engine->packet_fwd;
Should we have a print here for user info, that mode has been changed or 
ignored.
> +	run_pkt_fwd_on_lcore(fc, packet_fwd);
>   	return 0;
>   }
>   
> diff --git a/app/test-pmd/testpmd.h b/app/test-pmd/testpmd.h
> index 2149ecd93a..2744fa4d76 100644
> --- a/app/test-pmd/testpmd.h
> +++ b/app/test-pmd/testpmd.h
> @@ -216,6 +216,12 @@ struct xstat_display_info {
>   	bool	 allocated;
>   };
>   
> +/** Application state of a queue. */
> +struct queue_state {
> +	/** The queue is stopped and should not be used. */
> +	bool stopped;
> +};
> +
>   /**
>    * The data structure associated with each port.
>    */
> @@ -256,6 +262,10 @@ struct rte_port {
>   	uint64_t		mbuf_dynf;
>   	const struct rte_eth_rxtx_callback *tx_set_dynf_cb[RTE_MAX_QUEUES_PER_PORT+1];
>   	struct xstat_display_info xstats_info;
> +	/** Per-Rx-queue state. */
> +	struct queue_state rxq_state[RTE_MAX_QUEUES_PER_PORT];
> +	/** Per-Tx-queue state. */
> +	struct queue_state txq_state[RTE_MAX_QUEUES_PER_PORT];
Can we think of adding rxq_state/txq_state as part of existing 
structures under rte_port->rte_eth_rxconf/rte_eth_txconf.
And if it helps, rather than bool can we use u8 with eth_dev defines-
#define RTE_ETH_QUEUE_STATE_STOPPED 0 /**< Queue stopped. */
#define RTE_ETH_QUEUE_STATE_STARTED 1 /**< Queue started. */
>   };
>   
>   /**