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staging: vt6655: vnt_tx_packet Correct TX order of OWNED_BY_NIC

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The state of m_td0TD0.f1Owner should change after the buff_addr
has been filled otherwise the device grabs the buffer too early.

m_td0TD0.f1Owner is protected by memory barriers on both sides
of change.

iTDUsed is best incremented after MACvTransmit.

It appears that f1Owner actually polls to do the memory transfer.

A back port patch will be needed for v3.19

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Cc: <stable@vger.kernel.org> # v4.0+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Malcolm Priestley 2015-04-21 22:33:00 +01:00 committed by Greg Kroah-Hartman
parent ad3fee9b17
commit d65d2b25d2
1 changed files with 7 additions and 8 deletions
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15
drivers/staging/vt6655/device_main.c
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@ -1206,14 +1206,6 @@ static int vnt_tx_packet(struct vnt_private *priv, struct sk_buff *skb)
if (dma_idx == TYPE_AC0DMA)
head_td->pTDInfo->byFlags = TD_FLAGS_NETIF_SKB;
priv->iTDUsed[dma_idx]++;
/* Take ownership */
wmb();
head_td->m_td0TD0.f1Owner = OWNED_BY_NIC;
/* get Next */
wmb();
priv->apCurrTD[dma_idx] = head_td->next;
spin_unlock_irqrestore(&priv->lock, flags);
@ -1234,11 +1226,18 @@ static int vnt_tx_packet(struct vnt_private *priv, struct sk_buff *skb)
head_td->buff_addr = cpu_to_le32(head_td->pTDInfo->skb_dma);
/* Poll Transmit the adapter */
wmb();
head_td->m_td0TD0.f1Owner = OWNED_BY_NIC;
wmb(); /* second memory barrier */
if (head_td->pTDInfo->byFlags & TD_FLAGS_NETIF_SKB)
MACvTransmitAC0(priv->PortOffset);
else
MACvTransmit0(priv->PortOffset);
priv->iTDUsed[dma_idx]++;
spin_unlock_irqrestore(&priv->lock, flags);
return 0;