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ravb: do not invalidate cache for RX buffer twice

PATCH In review Sergei Shtylyov 2 participants 4 messages Jul 14, 2015 – Jul 17, 2015

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Sergei Shtylyov

author
#0 lore raw

PATCH 1/1 ravb: do not invalidate cache for RX buffer twice

First, dma_sync_single_for_cpu() shouldn't have been called in the first place (it's a streaming DMA API). dma_unmap_single() should have been called instead. Second, dma_unmap_single() call after handing the buffer to napi_gro_receive() makes little sense.

Signed-off-by Sergei Shtylyov <[email protected]>

---
The patch is against Dave Miller's 'net.git' repo.

Don't know why I missed this DMA API misuse while working on the driver. :-<

 drivers/net/ethernet/renesas/ravb_main.c |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

Index: net/drivers/net/ethernet/renesas/ravb_main.c =================================--- net.orig/drivers/net/ethernet/renesas/ravb_main.c +++ net/drivers/net/ethernet/renesas/ravb_main.c
@@ -543,10 +543,9 @@ static bool ravb_rx(struct net_device *n

skb = priv->rx_skb[q][entry]; priv->rx_skb[q][entry] = NULL;
- dma_sync_single_for_cpu(&ndev->dev,
- le32_to_cpu(desc->dptr),
- ALIGN(PKT_BUF_SZ, 16),
- DMA_FROM_DEVICE);
+ dma_unmap_single(&ndev->dev, le32_to_cpu(desc->dptr),
+ ALIGN(PKT_BUF_SZ, 16),
+ DMA_FROM_DEVICE);
get_ts &= (q = RAVB_NC) ?
RAVB_RXTSTAMP_TYPE_V2_L2_EVENT :
~RAVB_RXTSTAMP_TYPE_V2_L2_EVENT;
@@ -584,9 +583,6 @@ static bool ravb_rx(struct net_device *n
if (!skb)
break; /* Better luck next round. */
ravb_set_buffer_align(skb);
- dma_unmap_single(&ndev->dev, le32_to_cpu(desc->dptr),
- ALIGN(PKT_BUF_SZ, 16),
- DMA_FROM_DEVICE);
dma_addr = dma_map_single(&ndev->dev, skb->data,
le16_to_cpu(desc->ds_cc), DMA_FROM_DEVICE);

author
#1 lore raw

Hello.

Quoted 2 lines · Sergei Shtylyov

First, dma_sync_single_for_cpu() shouldn't have been called in the first place (it's a streaming DMA API). dma_unmap_single() should have been called instead.

^
Oops, I meant comma here.

Quoted 2 lines

Second, dma_unmap_single() call after handing the buffer to napi_gro_receive() makes little sense.

    Moreover, 'desc->dptr' may not be valid at this point...
Quoted 6 lines
Signed-off-by Sergei Shtylyov <[email protected]>

---
The patch is against Dave Miller's 'net.git' repo.

Don't know why I missed this DMA API misuse while working on the driver. :-<

Dave, do you want me to resend the patch with fixed up changelog?

Quoted 6 lines
  drivers/net/ethernet/renesas/ravb_main.c |   10 +++-------
  1 file changed, 3 insertions(+), 7 deletions(-)

Index: net/drivers/net/ethernet/renesas/ravb_main.c =================================> --- net.orig/drivers/net/ethernet/renesas/ravb_main.c +++ net/drivers/net/ethernet/renesas/ravb_main.c

[...]

Review static bool ravb_rx(struct net_device *n · line 588

Quoted 10 lines
(quoted diff) +0 -3
@@ -584,9 +583,6 @@ static bool ravb_rx(struct net_device *n
  			if (!skb)
  				break;	/* Better luck next round. */
  			ravb_set_buffer_align(skb);
-			dma_unmap_single(&ndev->dev, le32_to_cpu(desc->dptr),
-					 ALIGN(PKT_BUF_SZ, 16),
-					 DMA_FROM_DEVICE);
  			dma_addr = dma_map_single(&ndev->dev, skb->data,
  						  le16_to_cpu(desc->ds_cc),
  						  DMA_FROM_DEVICE);

WBR, Sergei

author
#2 lore raw
Quoted 10 lines · Sergei Shtylyov
Quoted 2 lines

First, dma_sync_single_for_cpu() shouldn't have been called in the first place (it's a streaming DMA API). dma_unmap_single() should have been called instead.

^
Oops, I meant comma here.

Quoted 2 lines

Second, dma_unmap_single() call after handing the buffer to napi_gro_receive() makes little sense.

    Moreover, 'desc->dptr' may not be valid at this point...
Quoted 8 lines
Quoted 6 lines
Signed-off-by Sergei Shtylyov <[email protected]>

---
The patch is against Dave Miller's 'net.git' repo.

Don't know why I missed this DMA API misuse while working on the driver. :-<

Dave, do you want me to resend the patch with fixed up changelog?

    Oops, forgot to CC Dave. :-(

WBR, Sergei

maintainer
#3 lore raw
In reply to Sergei Shtylyov

From: Sergei Shtylyov <[email protected]>
Date: Wed, 15 Jul 2015 00:56:52 +0300

Quoted 6 lines

First, dma_sync_single_for_cpu() shouldn't have been called in the first place (it's a streaming DMA API). dma_unmap_single() should have been called instead. Second, dma_unmap_single() call after handing the buffer to napi_gro_receive() makes little sense.

Signed-off-by Sergei Shtylyov <[email protected]>

Applied with fixed up commit log message, thanks.