RE: [PATCH net v2 3/4] bnxt: make sure xmit_more + errors does not miss doorbells

From: Jakub Kicinski

Sent: 11 August 2021 22:38

skbs are freed on error and not put on the ring. We may, however,
be in a situation where we're freeing the last skb of a batch,
and there is a doorbell ring pending because of xmit_more() being
true earlier. Make sure we ring the door bell in such situations.

Since errors are rare don't pay attention to xmit_more() and just
always flush the pending frames.

...

+tx_free:
 	dev_kfree_skb_any(skb);
+tx_kick_pending:
+	tx_buf->skb = NULL;
+	if (txr->kick_pending)
+		bnxt_txr_db_kick(bp, txr, txr->tx_prod);
 	return NETDEV_TX_OK;

Is this case actually so unlikely that the 'kick' can be
done unconditionally?
Then all the conditionals can be removed from the hot path.

	David

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