> -----Original Message-----
> From: Wang, Haiyue
> Sent: Tuesday, September 28, 2021 11:06
> To: 'Julien Meunier' <julien.meun...@nokia.com>; dev@dpdk.org
> Cc: sta...@dpdk.org; Richardson, Bruce <bruce.richard...@intel.com>
> Subject: RE: [PATCH] net/ixgbe: fix RxQ/TxQ release
>
> > -----Original Message-----
> > From: Julien Meunier <julien.meun...@nokia.com>
> > Sent: Tuesday, September 28, 2021 01:18
> > To: dev@dpdk.org
> > Cc: sta...@dpdk.org; Richardson, Bruce <bruce.richard...@intel.com>; Wang,
> > Haiyue
> > <haiyue.w...@intel.com>
> > Subject: [PATCH] net/ixgbe: fix RxQ/TxQ release
> >
> > On the vector implementation, during the tear-down, the mbufs not
> > drained in the RxQ and TxQ are freed based on an algorithm which
> > supposed that the number of descriptors is a power of 2 (max_desc).
> > Based on this hypothesis, this algorithm uses a bitmask in order to
> > detect an index overflow during the iteration, and to restart the loop
> > from 0.
> >
> > However, there is no such power of 2 requirement in the ixgbe for the
> > number of descriptors in the RxQ / TxQ. The only requirement is to have
> > a number correctly aligned.
> >
> > If a user requested to configure a number of descriptors which is not a
> > power of 2, as a consequence, during the tear-down, it was possible to
> > be in an infinite loop, and to never reach the exit loop condition.
> >
>
> Are you able to setup not a power of 2 successfully ?
>
My fault, yes, possible. ;-)
> int
> rte_eth_tx_queue_setup(uint16_t port_id, uint16_t tx_queue_id,
> uint16_t nb_tx_desc, unsigned int socket_id,
> const struct rte_eth_txconf *tx_conf)
> {
> ...
>
> if (nb_tx_desc > dev_info.tx_desc_lim.nb_max ||
> nb_tx_desc < dev_info.tx_desc_lim.nb_min ||
> nb_tx_desc % dev_info.tx_desc_lim.nb_align != 0) {
> RTE_ETHDEV_LOG(ERR,
> "Invalid value for nb_tx_desc(=%hu), should be: <= %hu,
> >= %hu, and a product
> of %hu\n",
> nb_tx_desc, dev_info.tx_desc_lim.nb_max,
> dev_info.tx_desc_lim.nb_min,
> dev_info.tx_desc_lim.nb_align);
> return -EINVAL;
> }
>
> ...
>
> }
>
> > By removing the bitmask and changing the loop method, we can avoid this
> > issue, and allow the user to configure a RxQ / TxQ which is not a power
> > of 2.
> >
> > Fixes: c95584dc2b18 ("ixgbe: new vectorized functions for Rx/Tx")
> > Cc: bruce.richard...@intel.com
> > Cc: sta...@dpdk.org
> >
> > Signed-off-by: Julien Meunier <julien.meun...@nokia.com>
> > ---
> > drivers/net/ixgbe/ixgbe_rxtx_vec_common.h | 20 +++++++++++++-------
> > 1 file changed, 13 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h
> > b/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h
> > index adba855ca3..8912558918 100644
> > --- a/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h
> > +++ b/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h
> > @@ -150,11 +150,14 @@ _ixgbe_tx_queue_release_mbufs_vec(struct
> > ixgbe_tx_queue *txq)
> > return;
> >
Just one line ?
i = (i + 1) % txq->nb_tx_desc
> > /* release the used mbufs in sw_ring */
> > - for (i = txq->tx_next_dd - (txq->tx_rs_thresh - 1);
> > - i != txq->tx_tail;
> > - i = (i + 1) & max_desc) {
> > + i = txq->tx_next_dd - (txq->tx_rs_thresh - 1);
> > + while (i != txq->tx_tail) {
> > txe = &txq->sw_ring_v[i];
> > rte_pktmbuf_free_seg(txe->mbuf);
> > +
> > + i = i + 1;
> > + if (i > max_desc)
> > + i = 0;
> > }
> > txq->nb_tx_free = max_desc;
> >
> > @@ -168,7 +171,7 @@ _ixgbe_tx_queue_release_mbufs_vec(struct ixgbe_tx_queue
> > *txq)
> > static inline void
> > _ixgbe_rx_queue_release_mbufs_vec(struct ixgbe_rx_queue *rxq)
> > {
> > - const unsigned int mask = rxq->nb_rx_desc - 1;
> > + const unsigned int max_desc = rxq->nb_rx_desc - 1;
> > unsigned int i;
> >
> > if (rxq->sw_ring == NULL || rxq->rxrearm_nb >= rxq->nb_rx_desc)
> > @@ -181,11 +184,14 @@ _ixgbe_rx_queue_release_mbufs_vec(struct
> > ixgbe_rx_queue *rxq)
> > rte_pktmbuf_free_seg(rxq->sw_ring[i].mbuf);
> > }
> > } else {
> > - for (i = rxq->rx_tail;
> > - i != rxq->rxrearm_start;
> > - i = (i + 1) & mask) {
> > + i = rxq->rx_tail;
> > + while (i != rxq->rxrearm_start) {
> > if (rxq->sw_ring[i].mbuf != NULL)
> > rte_pktmbuf_free_seg(rxq->sw_ring[i].mbuf);
> > +
> > + i = i + 1;
> > + if (i > max_desc)
> > + i = 0;
> > }
> > }
> >
> > --
> > 2.17.1
