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ixgbe: flush when in xmit_more mode and under descriptor pressure

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When xmit_more mode is being used and the ring is about to
become full or the stack has stopped the ring, enforce a tail
pointer write to the hw. Otherwise, we could risk a TX hang.

Code suggested by Alexander Duyck.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2014-08-26 19:34:18 +02:00 committed by David S. Miller
parent 900405d014
commit 2367a17390
1 changed files with 34 additions and 29 deletions
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63
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
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@ -6837,6 +6837,36 @@ static void ixgbe_tx_olinfo_status(union ixgbe_adv_tx_desc *tx_desc,
tx_desc->read.olinfo_status = cpu_to_le32(olinfo_status);
}
static int __ixgbe_maybe_stop_tx(struct ixgbe_ring *tx_ring, u16 size)
{
netif_stop_subqueue(tx_ring->netdev, tx_ring->queue_index);
/* Herbert's original patch had:
* smp_mb__after_netif_stop_queue();
* but since that doesn't exist yet, just open code it.
*/
smp_mb();
/* We need to check again in a case another CPU has just
* made room available.
*/
if (likely(ixgbe_desc_unused(tx_ring) < size))
return -EBUSY;
/* A reprieve! - use start_queue because it doesn't call schedule */
netif_start_subqueue(tx_ring->netdev, tx_ring->queue_index);
++tx_ring->tx_stats.restart_queue;
return 0;
}
static inline int ixgbe_maybe_stop_tx(struct ixgbe_ring *tx_ring, u16 size)
{
if (likely(ixgbe_desc_unused(tx_ring) >= size))
return 0;
return __ixgbe_maybe_stop_tx(tx_ring, size);
}
#define IXGBE_TXD_CMD (IXGBE_TXD_CMD_EOP | \
IXGBE_TXD_CMD_RS)
@ -6958,10 +6988,13 @@ static void ixgbe_tx_map(struct ixgbe_ring *tx_ring,
tx_ring->next_to_use = i;
if (!skb->xmit_more) {
ixgbe_maybe_stop_tx(tx_ring, DESC_NEEDED);
if (netif_xmit_stopped(txring_txq(tx_ring)) || !skb->xmit_more) {
/* notify HW of packet */
ixgbe_write_tail(tx_ring, i);
}
return;
dma_error:
dev_err(tx_ring->dev, "TX DMA map failed\n");
@ -7068,32 +7101,6 @@ static void ixgbe_atr(struct ixgbe_ring *ring,
input, common, ring->queue_index);
}
static int __ixgbe_maybe_stop_tx(struct ixgbe_ring *tx_ring, u16 size)
{
netif_stop_subqueue(tx_ring->netdev, tx_ring->queue_index);
/* Herbert's original patch had:
* smp_mb__after_netif_stop_queue();
* but since that doesn't exist yet, just open code it. */
smp_mb();
/* We need to check again in a case another CPU has just
* made room available. */
if (likely(ixgbe_desc_unused(tx_ring) < size))
return -EBUSY;
/* A reprieve! - use start_queue because it doesn't call schedule */
netif_start_subqueue(tx_ring->netdev, tx_ring->queue_index);
++tx_ring->tx_stats.restart_queue;
return 0;
}
static inline int ixgbe_maybe_stop_tx(struct ixgbe_ring *tx_ring, u16 size)
{
if (likely(ixgbe_desc_unused(tx_ring) >= size))
return 0;
return __ixgbe_maybe_stop_tx(tx_ring, size);
}
static u16 ixgbe_select_queue(struct net_device *dev, struct sk_buff *skb,
void *accel_priv, select_queue_fallback_t fallback)
{
@ -7262,8 +7269,6 @@ xmit_fcoe:
#endif /* IXGBE_FCOE */
ixgbe_tx_map(tx_ring, first, hdr_len);
ixgbe_maybe_stop_tx(tx_ring, DESC_NEEDED);
return NETDEV_TX_OK;
out_drop: