bnxt_en: Extend queue stop/start for TX rings

JIRA: https://issues.redhat.com/browse/RHEL-76565

commit fe96d71
Author: Somnath Kotur <somnath.kotur@broadcom.com>
Date:   Wed Feb 12 17:12:38 2025 -0800

    bnxt_en: Extend queue stop/start for TX rings

    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.  If TPH is
    not enabled, we just stop the TX ring without freeing the TX/TX cmpl
    rings.  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.  We don't expect to hit this error path because re-allocating
    previously reserved and allocated rings with the same parameters
    should never fail.

    Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
    Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
    Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
    Signed-off-by: Michael Chan <michael.chan@broadcom.com>
    Link: https://patch.msgid.link/20250213011240.1640031-11-michael.chan@broadcom.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Shruti Parab <shruti.parab@broadcom.com>

Author: Shruti Parab

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -11259,6 +11259,78 @@ 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);
+			}
+		}
+
+		if (!bp->tph_mode)
+			continue;
+
+		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];
+	/* All rings have been reserved and previously allocated.
+	 * Reallocating with the same parameters should never fail.
+	 */
+	bnxt_for_each_napi_tx(i, bnapi, txr) {
+		if (!bp->tph_mode)
+			goto start_tx;
+
+		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)
+			return rc;
+
+		txr->tx_prod = 0;
+		txr->tx_cons = 0;
+		txr->tx_hw_cons = 0;
+start_tx:
+		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;
@@ -15621,7 +15693,9 @@ static int bnxt_queue_start(struct net_device *dev, void *qmem, int idx)
 {
 	struct bnxt *bp = netdev_priv(dev);
 	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];
@@ -15639,27 +15713,39 @@ static int bnxt_queue_start(struct net_device *dev, void *qmem, int idx)
 
 	bnxt_copy_rx_ring(bp, rxr, clone);
 
+	bnapi = rxr->bnapi;
+	cpr = &bnapi->cp_ring;
+
 	/* All rings have been reserved and previously allocated.
 	 * Reallocating with the same parameters should never fail.
 	 */
 	rc = bnxt_hwrm_rx_ring_alloc(bp, rxr);
 	if (rc)
-		return rc;
+		goto err_reset;
 
 	if (bp->tph_mode) {
 		rc = bnxt_hwrm_cp_ring_alloc_p5(bp, rxr->rx_cpr);
 		if (rc)
-			goto err_free_hwrm_rx_ring;
+			goto err_reset;
 	}
 
 	rc = bnxt_hwrm_rx_agg_ring_alloc(bp, rxr);
 	if (rc)
-		goto err_free_hwrm_cp_ring;
+		goto err_reset;
 
 	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);
 
+	if (bp->flags & BNXT_FLAG_SHARED_RINGS) {
+		rc = bnxt_tx_queue_start(bp, idx);
+		if (rc)
+			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];
 
@@ -15676,19 +15762,22 @@ static int bnxt_queue_start(struct net_device *dev, void *qmem, int idx)
 
 	return 0;
 
-err_free_hwrm_cp_ring:
-	if (bp->tph_mode)
-		bnxt_hwrm_cp_ring_free(bp, rxr->rx_cpr);
-err_free_hwrm_rx_ring:
-	bnxt_hwrm_rx_ring_free(bp, rxr, false);
+err_reset:
+	netdev_err(bp->dev, "Unexpected HWRM error during queue start rc: %d\n",
+		   rc);
+	napi_enable(&bnapi->napi);
+	bnxt_db_nq_arm(bp, &cpr->cp_db, cpr->cp_raw_cons);
+	bnxt_reset_task(bp, true);
 	return rc;
 }
 
 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++) {
@@ -15700,17 +15789,29 @@ 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);
+
+	/* Disable NAPI now after freeing the rings because HWRM_RING_FREE
+	 * completion is handled in NAPI to guarantee no more DMA on that ring
+	 * after seeing the completion.
+	 */
+	napi_disable(&bnapi->napi);
+
 	if (bp->tph_mode) {
 		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);