On Mon, 31 Jul 2023 16:49:59 +0530 Md Danish Anwar wrote: > There are five error handling cases in xmit(). > > 1. DMA Mapping the linear buffer -- If we fail to map dma, we will return > NETDEV_TX_OK and goto drop_free_skb which will free the skb and drop the packet. > > 2. Allocating descriptor for linear buffer -- If we fail to allocate descriptor > this means it is a occupancy issue and we will goto drop_stop_q_busy which will > stop queue and return NETDEV_TX_BUSY. > > 3. Allocating descriptor when skb is fragmented. -- If we fail to allocate > descriptor when skb is fragmented, we will goto drop_stop_q which will stop the > queue, free the descriptor, free the skb, drop the packet and return NETDEV_TX_OK. This one should be BUSY, right? goto free_desc_stop_q_busy > 4. DMA mapping for fragment. -- If DMA mapping for fragment fails, we will go > to drop_free_descs which will free the descriptor, free the skb, drop the > packet and return NETDEV_TX_OK. > > 5. Tx push failed. -- If tx push fails we will goto drop_free_descs which will > free the descriptor, free the skb, drop the packet and return. > > We will only stop queue in case 2 and 3 where we failed to allocate descriptor. > In case 1, 4 and 5 we are encountering dma mapping error, so for these cases we > will not stop the queue. > > Below will be my goto labels. > > drop_stop_q: > netif_tx_stop_queue(netif_txq); > > drop_free_descs: > prueth_xmit_free(tx_chn, first_desc); > > drop_free_skb: > dev_kfree_skb_any(skb); > > /* error */ > ndev->stats.tx_dropped++; > netdev_err(ndev, "tx: error: %d\n", ret); > > return ret; free_desc_stop_q_busy: prueth_xmit_free(tx_chn, first_desc); > drop_stop_q_busy: > netif_tx_stop_queue(netif_txq); > return NETDEV_TX_BUSY;
