This is a note to let you know that I've just added the patch titled
staging: vt6655: vnt_tx_packet Correct TX order of OWNED_BY_NIC
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From d65d2b25d2761153390df8026cca1a528d9b6c5a Mon Sep 17 00:00:00 2001
From: Malcolm Priestley <tvboxspy@xxxxxxxxx>
Date: Tue, 21 Apr 2015 22:33:00 +0100
Subject: 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 <tvboxspy@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v4.0+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
--
2.4.0
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