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Commit d65d2b25 authored by Malcolm Priestley's avatar Malcolm Priestley Committed by Greg Kroah-Hartman
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staging: vt6655: vnt_tx_packet Correct TX order of OWNED_BY_NIC 



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: default avatarMalcolm Priestley <tvboxspy@gmail.com>
Cc: <stable@vger.kernel.org> # v4.0+
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ad3fee9b

drivers/staging/vt6655/device_main.c

+7 −8
Original line number Diff line number Diff line
@@ -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;