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igb: Change Tx cleanup loop to do/while instead of for

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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: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Alexander Duyck 2012-09-13 06:28:01 +00:00 committed by Jeff Kirsher
parent f33005a637
commit f4128785b8
1 changed files with 16 additions and 12 deletions
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28
drivers/net/ethernet/intel/igb/igb_main.c
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@ -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);