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Message-ID: <Z4n/CkPn1v+eydD2@mev-dev.igk.intel.com>
Date: Fri, 17 Jan 2025 07:56:10 +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,
helgaas@...nel.org, Somnath Kotur <somnath.kotur@...adcom.com>,
Ajit Khaparde <ajit.khaparde@...adcom.com>,
David Wei <dw@...idwei.uk>
Subject: Re: [PATCH net-next v2 09/10] bnxt_en: Extend queue stop/start for
TX rings
On Thu, Jan 16, 2025 at 11:23:42AM -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. Explicitly re-arm the NQ after
> napi_enable() in queue start so that NAPI will resume properly.
>
> Error handling in bnxt_queue_start() requires a reset. If a TX
> ring cannot be allocated or initialized properly, it will cause
> TX timeout. The reset will also free any partially allocated
> rings.
>
> Reviewed-by: Ajit Khaparde <ajit.khaparde@...adcom.com>
> Signed-off-by: Somnath Kotur <somnath.kotur@...adcom.com>
> Signed-off-by: Michael Chan <michael.chan@...adcom.com>
> ---
> Cc: David Wei <dw@...idwei.uk>
>
> v2:
> Add reset for error handling in queue_start().
> Fix compile error.
>
> 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 | 124 ++++++++++++++++++++--
> 1 file changed, 115 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index 53279904cdb5..0a10a4cffcc8 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -7346,6 +7346,22 @@ static int hwrm_ring_free_send_msg(struct bnxt *bp,
> return 0;
> }
>
[...]
> static void bnxt_free_irq(struct bnxt *bp)
> {
> struct bnxt_irq *irq;
> @@ -15616,6 +15694,7 @@ static int bnxt_queue_start(struct net_device *dev, void *qmem, int idx)
> struct bnxt_rx_ring_info *rxr, *clone;
> struct bnxt_cp_ring_info *cpr;
> struct bnxt_vnic_info *vnic;
> + struct bnxt_napi *bnapi;
> int i, rc;
>
> rxr = &bp->rx_ring[idx];
> @@ -15633,25 +15712,40 @@ static int bnxt_queue_start(struct net_device *dev, void *qmem, int idx)
>
> bnxt_copy_rx_ring(bp, rxr, clone);
>
> + bnapi = rxr->bnapi;
> rc = bnxt_hwrm_rx_ring_alloc(bp, rxr);
> if (rc)
> - return rc;
> + goto err_reset_rx;
>
> rc = bnxt_hwrm_cp_ring_alloc_p5(bp, rxr->rx_cpr);
> if (rc)
> - goto err_free_hwrm_rx_ring;
> + goto err_reset_rx;
>
> rc = bnxt_hwrm_rx_agg_ring_alloc(bp, rxr);
> if (rc)
> - goto err_free_hwrm_cp_ring;
> + goto err_reset_rx;
>
> bnxt_db_write(bp, &rxr->rx_db, rxr->rx_prod);
> if (bp->flags & BNXT_FLAG_AGG_RINGS)
> bnxt_db_write(bp, &rxr->rx_agg_db, rxr->rx_agg_prod);
>
> - cpr = &rxr->bnapi->cp_ring;
> + cpr = &bnapi->cp_ring;
> cpr->sw_stats->rx.rx_resets++;
>
> + if (bp->flags & BNXT_FLAG_SHARED_RINGS) {
> + cpr->sw_stats->tx.tx_resets++;
> + rc = bnxt_tx_queue_start(bp, idx);
> + if (rc) {
> + netdev_warn(bp->dev,
> + "tx queue restart failed: rc=%d\n", rc);
> + bnapi->tx_fault = 1;
> + goto err_reset;
> + }
> + }
> +
> + napi_enable(&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];
>
> @@ -15668,10 +15762,12 @@ static int bnxt_queue_start(struct net_device *dev, void *qmem, int idx)
>
> return 0;
>
> -err_free_hwrm_cp_ring:
> - bnxt_hwrm_cp_ring_free(bp, rxr->rx_cpr);
> -err_free_hwrm_rx_ring:
> - bnxt_hwrm_rx_ring_free(bp, rxr, false);
It looked good to have partial freeing here, but as reset can do the
same it is fine to drop it.
Thanks for fixing the error path.
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
> +err_reset_rx:
> + rxr->bnapi->in_reset = true;
> +err_reset:
> + napi_enable(&bnapi->napi);
> + bnxt_db_nq_arm(bp, &cpr->cp_db, cpr->cp_raw_cons);
> + bnxt_reset_task(bp, true);
> return rc;
> }
>
> @@ -15679,7 +15775,9 @@ 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_cp_ring_info *cpr;
> struct bnxt_vnic_info *vnic;
> + struct bnxt_napi *bnapi;
> int i;
>
> for (i = 0; i <= BNXT_VNIC_NTUPLE; i++) {
> @@ -15691,15 +15789,23 @@ 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;
> + cpr = &bnapi->cp_ring;
> + cancel_work_sync(&cpr->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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