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Commit f4128785 authored by Alexander Duyck's avatar Alexander Duyck Committed by Jeff Kirsher
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igb: Change Tx cleanup loop to do/while instead of for 



This change makes it so that Tx cleanup is done in a do/while loop instead
of a for loop.  The main motivation behind this is the fact that we should
never be invoked with a budget less than 1 so we can skip checking the
budget before processing the first descriptor.

Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Tested-by: default avatarAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
parent f33005a6

drivers/net/ethernet/intel/igb/igb_main.c

+16 −12
Original line number Diff line number Diff line
@@ -5690,7 +5690,7 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector) 
	struct igb_adapter *adapter = q_vector->adapter;

	struct igb_ring *tx_ring = q_vector->tx.ring;

	struct igb_tx_buffer *tx_buffer;

	union e1000_adv_tx_desc *tx_desc, *eop_desc;

	union e1000_adv_tx_desc *tx_desc;

	unsigned int total_bytes = 0, total_packets = 0;

	unsigned int budget = q_vector->tx.work_limit;

	unsigned int i = tx_ring->next_to_clean;
@@ -5702,16 +5702,16 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector) 
	tx_desc = IGB_TX_DESC(tx_ring, i);

	i -= tx_ring->count;



	for (; budget; budget--) {

		eop_desc = tx_buffer->next_to_watch;



		/* prevent any other reads prior to eop_desc */

		rmb();

	do {

		union e1000_adv_tx_desc *eop_desc = tx_buffer->next_to_watch;



		/* if next_to_watch is not set then there is no work pending */

		if (!eop_desc)

			break;



		/* prevent any other reads prior to eop_desc */

		rmb();



		/* if DD is not set pending work has not been completed */

		if (!(eop_desc->wb.status & cpu_to_le32(E1000_TXD_STAT_DD)))

			break;
@@ -5767,7 +5767,13 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector) 
			tx_buffer = tx_ring->tx_buffer_info;

			tx_desc = IGB_TX_DESC(tx_ring, 0);

		}

	}



		/* issue prefetch for next Tx descriptor */

		prefetch(tx_desc);



		/* update budget accounting */

		budget--;

	} while (likely(budget));



	netdev_tx_completed_queue(txring_txq(tx_ring),

				  total_packets, total_bytes);
@@ -5783,12 +5789,10 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector) 
	if (test_bit(IGB_RING_FLAG_TX_DETECT_HANG, &tx_ring->flags)) {

		struct e1000_hw *hw = &adapter->hw;



		eop_desc = tx_buffer->next_to_watch;



		/* Detect a transmit hang in hardware, this serializes the

		 * check with the clearing of time_stamp and movement of i */

		clear_bit(IGB_RING_FLAG_TX_DETECT_HANG, &tx_ring->flags);

		if (eop_desc &&

		if (tx_buffer->next_to_watch &&

		    time_after(jiffies, tx_buffer->time_stamp +

			       (adapter->tx_timeout_factor * HZ)) &&

		    !(rd32(E1000_STATUS) & E1000_STATUS_TXOFF)) {
@@ -5812,9 +5816,9 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector) 
				tx_ring->next_to_use,

				tx_ring->next_to_clean,

				tx_buffer->time_stamp,

				eop_desc,

				tx_buffer->next_to_watch,

				jiffies,

				eop_desc->wb.status);

				tx_buffer->next_to_watch->wb.status);

			netif_stop_subqueue(tx_ring->netdev,

					    tx_ring->queue_index);