Re: [PATCH 2/2] drivers/net: support single queue per port

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Oct 25, 2024 at 11:52:23AM +0000, Morten Brørup wrote:
> When configuring DPDK for one queue per port
> (#define RTE_MAX_QUEUES_PER_PORT 1), compilation of some network drivers
> fails with e.g.:
> 
> ../drivers/net/bnxt/bnxt_rxq.c: In function 'bnxt_rx_queue_stop':
> ../drivers/net/bnxt/bnxt_rxq.c:587:34: error: array subscript 1 is above array bounds of 'uint8_t[1]' {aka 'unsigned char[1]'} [-Werror=array-bounds=]
>   587 |         dev->data->rx_queue_state[q_id] = RTE_ETH_QUEUE_STATE_STOPPED;
>       |         ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
> In file included from ../drivers/net/bnxt/bnxt.h:16,
>                  from ../drivers/net/bnxt/bnxt_rxq.c:10:
> ../lib/ethdev/ethdev_driver.h:168:17: note: while referencing 'rx_queue_state'
>   168 |         uint8_t rx_queue_state[RTE_MAX_QUEUES_PER_PORT];
>       |                 ^~~~~~~~~~~~~~
> 
> To fix this, a hint is added to the network drivers where a compiler in
> the CI has been seen to emit the above error when DPDK is configured for
> one queue per port, but we know that the error cannot occur.
> 
> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> ---
>  drivers/net/bnxt/bnxt_ethdev.c      |  2 ++
>  drivers/net/bnxt/bnxt_rxq.c         |  1 +
>  drivers/net/e1000/igb_rxtx.c        |  2 ++
>  drivers/net/failsafe/failsafe_ops.c | 10 ++++++++--
>  drivers/net/hns3/hns3_rxtx.c        |  2 ++
>  drivers/net/mana/tx.c               |  1 +
>  6 files changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/bnxt/bnxt_ethdev.c b/drivers/net/bnxt/bnxt_ethdev.c
> index 1f7c0d77d5..136e308437 100644
> --- a/drivers/net/bnxt/bnxt_ethdev.c
> +++ b/drivers/net/bnxt/bnxt_ethdev.c
> @@ -910,6 +910,7 @@ static int bnxt_start_nic(struct bnxt *bp)
>  		struct bnxt_rx_queue *rxq = bp->rx_queues[j];
>  
>  		if (!rxq->rx_deferred_start) {
> +			__rte_assume(j < RTE_MAX_QUEUES_PER_PORT);
>  			bp->eth_dev->data->rx_queue_state[j] =
>  				RTE_ETH_QUEUE_STATE_STARTED;
>  			rxq->rx_started = true;
> @@ -930,6 +931,7 @@ static int bnxt_start_nic(struct bnxt *bp)
>  		struct bnxt_tx_queue *txq = bp->tx_queues[j];
>  
>  		if (!txq->tx_deferred_start) {
> +			__rte_assume(j < RTE_MAX_QUEUES_PER_PORT);
>  			bp->eth_dev->data->tx_queue_state[j] =
>  				RTE_ETH_QUEUE_STATE_STARTED;
>  			txq->tx_started = true;
> diff --git a/drivers/net/bnxt/bnxt_rxq.c b/drivers/net/bnxt/bnxt_rxq.c
> index 1c25c57ca6..1651c26545 100644
> --- a/drivers/net/bnxt/bnxt_rxq.c
> +++ b/drivers/net/bnxt/bnxt_rxq.c
> @@ -584,6 +584,7 @@ int bnxt_rx_queue_stop(struct rte_eth_dev *dev, uint16_t rx_queue_id)
>  		return -EINVAL;
>  	}
>  
> +	__rte_assume(q_id < RTE_MAX_QUEUES_PER_PORT);
>  	dev->data->rx_queue_state[q_id] = RTE_ETH_QUEUE_STATE_STOPPED;
>  	rxq->rx_started = false;
>  	PMD_DRV_LOG_LINE(DEBUG, "Rx queue stopped");
> diff --git a/drivers/net/e1000/igb_rxtx.c b/drivers/net/e1000/igb_rxtx.c
> index d61eaad2de..4276bb6d31 100644
> --- a/drivers/net/e1000/igb_rxtx.c
> +++ b/drivers/net/e1000/igb_rxtx.c
> @@ -1868,6 +1868,7 @@ igb_dev_clear_queues(struct rte_eth_dev *dev)
>  	struct igb_rx_queue *rxq;
>  
>  	for (i = 0; i < dev->data->nb_tx_queues; i++) {
> +		__rte_assume(i < RTE_MAX_QUEUES_PER_PORT);
>  		txq = dev->data->tx_queues[i];
>  		if (txq != NULL) {
>  			igb_tx_queue_release_mbufs(txq);
> @@ -1877,6 +1878,7 @@ igb_dev_clear_queues(struct rte_eth_dev *dev)
>  	}
>  
>  	for (i = 0; i < dev->data->nb_rx_queues; i++) {
> +		__rte_assume(i < RTE_MAX_QUEUES_PER_PORT);
>  		rxq = dev->data->rx_queues[i];
>  		if (rxq != NULL) {
>  			igb_rx_queue_release_mbufs(rxq);

For e1000, this is fine.

Acked-by: Bruce Richardson <bruce.richardson@intel.com>

BTW: is this the only/best way to put in the assumption? If it were me, I'd
look to put before the loop the underlying assumption that
(dev->data->nb_XX_queues < RTE_MAX_QUEUES_PER_PORT), rather than putting
the assumption on "i".

/Bruce