From d65d2b25d2761153390df8026cca1a528d9b6c5a Mon Sep 17 00:00:00 2001 From: Malcolm Priestley Date: Tue, 21 Apr 2015 22:33:00 +0100 Subject: [PATCH] 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: Malcolm Priestley Cc: # v4.0+ Signed-off-by: Greg Kroah-Hartman --- drivers/staging/vt6655/device_main.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/staging/vt6655/device_main.c b/drivers/staging/vt6655/device_main.c index c81776363d8e..930bbbebc102 100644 --- a/drivers/staging/vt6655/device_main.c +++ b/drivers/staging/vt6655/device_main.c @@ -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; -- 2.20.1