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Message-ID: <Z4TRYfno5jCz84KD@mev-dev.igk.intel.com>
Date: Mon, 13 Jan 2025 09:40:01 +0100
From: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
To: Michael Chan <michael.chan@...adcom.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
kuba@...nel.org, pabeni@...hat.com, andrew+netdev@...n.ch,
pavan.chebbi@...adcom.com, andrew.gospodarek@...adcom.com,
somnath.kotur@...adcom.com,
Ajit Khaparde <ajit.khaparde@...adcom.com>,
David Wei <dw@...idwei.uk>
Subject: Re: [PATCH net-next 09/10] bnxt_en: Extend queue stop/start for Tx
rings
On Sun, Jan 12, 2025 at 10:39:26PM -0800, Michael Chan wrote:
> From: Somnath Kotur <somnath.kotur@...adcom.com>
>
> In order to use queue_stop/queue_start to support the new Steering
> Tags, we need to free the TX ring and TX completion ring if it is a
> combined channel with TX/RX sharing the same NAPI. Otherwise
> TX completions will not have the updated Steering Tag. With that
> we can now add napi_disable() and napi_enable() during queue_stop()/
> queue_start(). This will guarantee that NAPI will stop processing
> the completion entries in case there are additional pending entries
> in the completion rings after queue_stop().
>
> There could be some NQEs sitting unprocessed while NAPI is disabled
> thereby leaving the NQ unarmed. Explictily Re-arm the NQ after
> napi_enable() in queue start so that NAPI will resume properly.
>
> Reviewed-by: Ajit Khaparde <ajit.khaparde@...adcom.com>
> Signed-off-by: Somnath Kotur <somnath.kotur@...adcom.com>
> Reviewed-by: Michael Chan <michael.chan@...adcom.com>
> ---
> Cc: David Wei <dw@...idwei.uk>
>
> Discussion about adding napi_disable()/napi_enable():
>
> https://lore.kernel.org/netdev/5336d624-8d8b-40a6-b732-b020e4a119a2@davidwei.uk/#t
> ---
> drivers/net/ethernet/broadcom/bnxt/bnxt.c | 99 ++++++++++++++++++++++-
> 1 file changed, 98 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index fe350d0ba99c..eddb4de959c6 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -7341,6 +7341,22 @@ static int hwrm_ring_free_send_msg(struct bnxt *bp,
> return 0;
> }
>
> +static void bnxt_hwrm_tx_ring_free(struct bnxt *bp, struct bnxt_tx_ring_info *txr,
> + bool close_path)
> +{
> + struct bnxt_ring_struct *ring = &txr->tx_ring_struct;
> + u32 cmpl_ring_id;
> +
> + if (ring->fw_ring_id == INVALID_HW_RING_ID)
> + return;
> +
> + cmpl_ring_id = close_path ? bnxt_cp_ring_for_tx(bp, txr) :
> + INVALID_HW_RING_ID;
> + hwrm_ring_free_send_msg(bp, ring, RING_FREE_REQ_RING_TYPE_TX,
> + cmpl_ring_id);
> + ring->fw_ring_id = INVALID_HW_RING_ID;
> +}
> +
> static void bnxt_hwrm_rx_ring_free(struct bnxt *bp,
> struct bnxt_rx_ring_info *rxr,
> bool close_path)
> @@ -11247,6 +11263,69 @@ int bnxt_reserve_rings(struct bnxt *bp, bool irq_re_init)
> return 0;
> }
>
> +static void bnxt_tx_queue_stop(struct bnxt *bp, int idx)
> +{
> + struct bnxt_tx_ring_info *txr;
> + struct netdev_queue *txq;
> + struct bnxt_napi *bnapi;
> + int i;
> +
> + bnapi = bp->bnapi[idx];
> + bnxt_for_each_napi_tx(i, bnapi, txr) {
> + WRITE_ONCE(txr->dev_state, BNXT_DEV_STATE_CLOSING);
> + synchronize_net();
> +
> + if (!(bnapi->flags & BNXT_NAPI_FLAG_XDP)) {
> + txq = netdev_get_tx_queue(bp->dev, txr->txq_index);
> + if (txq) {
> + __netif_tx_lock_bh(txq);
> + netif_tx_stop_queue(txq);
> + __netif_tx_unlock_bh(txq);
> + }
> + }
> + bnxt_hwrm_tx_ring_free(bp, txr, true);
> + bnxt_hwrm_cp_ring_free(bp, txr->tx_cpr);
> + bnxt_free_one_tx_ring_skbs(bp, txr, txr->txq_index);
> + bnxt_clear_one_cp_ring(bp, txr->tx_cpr);
> + }
> +}
> +
> +static int bnxt_tx_queue_start(struct bnxt *bp, int idx)
> +{
> + struct bnxt_tx_ring_info *txr;
> + struct netdev_queue *txq;
> + struct bnxt_napi *bnapi;
> + int rc, i;
> +
> + bnapi = bp->bnapi[idx];
> + bnxt_for_each_napi_tx(i, bnapi, txr) {
> + rc = bnxt_hwrm_cp_ring_alloc_p5(bp, txr->tx_cpr);
> + if (rc)
> + return rc;
> +
> + rc = bnxt_hwrm_tx_ring_alloc(bp, txr, false);
> + if (rc) {
> + bnxt_hwrm_cp_ring_free(bp, txr->tx_cpr);
What about ring allocated in previous steps? Don't you need to free them
too?
> + return rc;
> + }
> + txr->tx_prod = 0;
> + txr->tx_cons = 0;
> + txr->tx_hw_cons = 0;
> +
> + WRITE_ONCE(txr->dev_state, 0);
> + synchronize_net();
> +
> + if (bnapi->flags & BNXT_NAPI_FLAG_XDP)
> + continue;
> +
> + txq = netdev_get_tx_queue(bp->dev, txr->txq_index);
> + if (txq)
> + netif_tx_start_queue(txq);
> + }
> +
> + return 0;
> +}
> +
> static void bnxt_free_irq(struct bnxt *bp)
> {
> struct bnxt_irq *irq;
> @@ -15647,6 +15726,16 @@ static int bnxt_queue_start(struct net_device *dev, void *qmem, int idx)
> cpr = &rxr->bnapi->cp_ring;
> cpr->sw_stats->rx.rx_resets++;
>
> + if (bp->flags & BNXT_FLAG_SHARED_RINGS) {
> + rc = bnxt_tx_queue_start(bp, idx);
> + if (rc)
> + netdev_warn(bp->dev,
> + "tx queue restart failed: rc=%d\n", rc);
> + }
> +
> + napi_enable(&rxr->bnapi->napi);
> + bnxt_db_nq_arm(bp, &cpr->cp_db, cpr->cp_raw_cons);
> +
> for (i = 0; i <= BNXT_VNIC_NTUPLE; i++) {
> vnic = &bp->vnic_info[i];
>
> @@ -15675,6 +15764,7 @@ static int bnxt_queue_stop(struct net_device *dev, void *qmem, int idx)
> struct bnxt *bp = netdev_priv(dev);
> struct bnxt_rx_ring_info *rxr;
> struct bnxt_vnic_info *vnic;
> + struct bnxt_napi *bnapi;
> int i;
>
> for (i = 0; i <= BNXT_VNIC_NTUPLE; i++) {
> @@ -15686,15 +15776,22 @@ static int bnxt_queue_stop(struct net_device *dev, void *qmem, int idx)
> /* Make sure NAPI sees that the VNIC is disabled */
> synchronize_net();
> rxr = &bp->rx_ring[idx];
> - cancel_work_sync(&rxr->bnapi->cp_ring.dim.work);
> + bnapi = rxr->bnapi;
> + cancel_work_sync(&bnapi->cp_ring.dim.work);
> bnxt_hwrm_rx_ring_free(bp, rxr, false);
> bnxt_hwrm_rx_agg_ring_free(bp, rxr, false);
> page_pool_disable_direct_recycling(rxr->page_pool);
> if (bnxt_separate_head_pool())
> page_pool_disable_direct_recycling(rxr->head_pool);
>
> + if (bp->flags & BNXT_FLAG_SHARED_RINGS)
> + bnxt_tx_queue_stop(bp, idx);
> +
> + napi_disable(&bnapi->napi);
> +
> bnxt_hwrm_cp_ring_free(bp, rxr->rx_cpr);
> bnxt_clear_one_cp_ring(bp, rxr->rx_cpr);
> + bnxt_db_nq(bp, &cpr->cp_db, cpr->cp_raw_cons);
>
> memcpy(qmem, rxr, sizeof(*rxr));
> bnxt_init_rx_ring_struct(bp, qmem);
> --
> 2.30.1
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