[net PATCH] atl1e: unmap partially mapped skb on dma error and free skb

[net PATCH] atl1e: unmap partially mapped skb on dma error and free skb

[Neil Horman]

Ben Hutchings pointed out that my recent update to atl1e:

commit 352900b583b2852152a1e05ea0e8b579292e731e
Author: Neil Horman <nhorman@tuxdriver.com>
Date:   Fri Jul 12 10:58:48 2013 -0400

    atl1e: fix dma mapping warnings

Was missing a bit of code.  Specifically it reset the hardware tx ring to its
origional state when we hit a dma error, but didn't unmap any exiting mappings
from the operation.  This patch fixes that up.  It also remembers to free the
skb in the event that an error occurs, so we don't leak.  Untested, as I don't
have hardware.  I think its pretty straightforward, but please review closely.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Ben Hutchings <bhutchings@solarflare.com>
CC: Jay Cliburn <jcliburn@gmail.com>
CC: Chris Snook <chris.snook@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
---
 drivers/net/ethernet/atheros/atl1e/atl1e_main.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/atheros/atl1e/atl1e_main.c b/drivers/net/ethernet/atheros/atl1e/atl1e_main.c
index 6d1a62a..1966444 100644
--- a/drivers/net/ethernet/atheros/atl1e/atl1e_main.c
+++ b/drivers/net/ethernet/atheros/atl1e/atl1e_main.c
@@ -1678,6 +1678,7 @@ static int atl1e_tx_map(struct atl1e_adapter *adapter,
 	u16 f;
 	int segment;
 	int ring_start = adapter->tx_ring.next_to_use;
+	int ring_end;
 
 	nr_frags = skb_shinfo(skb)->nr_frags;
 	segment = (tpd->word3 >> TPD_SEGMENT_EN_SHIFT) & TPD_SEGMENT_EN_MASK;
@@ -1721,6 +1722,15 @@ static int atl1e_tx_map(struct atl1e_adapter *adapter,
 					map_len, PCI_DMA_TODEVICE);
 
 		if (dma_mapping_error(&adapter->pdev->dev, tx_buffer->dma)) {
+			/* We need to unwind the mappings we've done */
+			ring_end = adapter->tx_ring.next_to_use;
+			adapter->tx_ring.next_to_use = ring_start;
+			while (adapter->tx_ring.next_to_use != ring_end) {
+				tpd = atl1e_get_tpd(adapter);
+				tx_buffer = atl1e_get_tx_buffer(adapter, tpd);
+				pci_unmap_single(adapter->pdev, tx_buffer->dma,
+						 tx_buffer->length, PCI_DMA_TODEVICE);
+			}
 			/* Reset the tx rings next pointer */
 			adapter->tx_ring.next_to_use = ring_start;
 			return -ENOSPC;
@@ -1763,6 +1773,16 @@ static int atl1e_tx_map(struct atl1e_adapter *adapter,
 							  DMA_TO_DEVICE);
 
 			if (dma_mapping_error(&adapter->pdev->dev, tx_buffer->dma)) {
+				/* We need to unwind the mappings we've done */
+				ring_end = adapter->tx_ring.next_to_use;
+				adapter->tx_ring.next_to_use = ring_start;
+				while (adapter->tx_ring.next_to_use != ring_end) {
+					tpd = atl1e_get_tpd(adapter);
+					tx_buffer = atl1e_get_tx_buffer(adapter, tpd);
+					dma_unmap_page(&adapter->pdev->dev, tx_buffer->dma,
+						       tx_buffer->length, DMA_TO_DEVICE);
+				}
+
 				/* Reset the ring next to use pointer */
 				adapter->tx_ring.next_to_use = ring_start;
 				return -ENOSPC;
@@ -1853,8 +1873,10 @@ static netdev_tx_t atl1e_xmit_frame(struct sk_buff *skb,
 		return NETDEV_TX_OK;
 	}
 
-	if (atl1e_tx_map(adapter, skb, tpd))
+	if (atl1e_tx_map(adapter, skb, tpd)) {
+		dev_kfree_skb_any(skb);
 		goto out;
+	}
 
 	atl1e_tx_queue(adapter, tpd_req, tpd);
 
-- 
1.8.1.4

Re: [net PATCH] atl1e: unmap partially mapped skb on dma error and free skb

[David Miller]

From: Neil Horman <nhorman@tuxdriver.com>
Date: Tue, 16 Jul 2013 10:49:41 -0400

> Ben Hutchings pointed out that my recent update to atl1e:
> 
> commit 352900b583b2852152a1e05ea0e8b579292e731e
> Author: Neil Horman <nhorman@tuxdriver.com>
> Date:   Fri Jul 12 10:58:48 2013 -0400
> 
>     atl1e: fix dma mapping warnings
> 
> Was missing a bit of code.  Specifically it reset the hardware tx ring to its
> origional state when we hit a dma error, but didn't unmap any exiting mappings
> from the operation.  This patch fixes that up.  It also remembers to free the
> skb in the event that an error occurs, so we don't leak.  Untested, as I don't
> have hardware.  I think its pretty straightforward, but please review closely.
> 
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>

Applied, but please refer to commits in the form "$SHA1ID ("Commit message
header line")", I fixed it up for you this time.

Re: [net PATCH] atl1e: unmap partially mapped skb on dma error and free skb

[Neil Horman]

On Tue, Jul 16, 2013 at 12:11:25PM -0700, David Miller wrote:
> From: Neil Horman <nhorman@tuxdriver.com>
> Date: Tue, 16 Jul 2013 10:49:41 -0400
> 
> > Ben Hutchings pointed out that my recent update to atl1e:
> > 
> > commit 352900b583b2852152a1e05ea0e8b579292e731e
> > Author: Neil Horman <nhorman@tuxdriver.com>
> > Date:   Fri Jul 12 10:58:48 2013 -0400
> > 
> >     atl1e: fix dma mapping warnings
> > 
> > Was missing a bit of code.  Specifically it reset the hardware tx ring to its
> > origional state when we hit a dma error, but didn't unmap any exiting mappings
> > from the operation.  This patch fixes that up.  It also remembers to free the
> > skb in the event that an error occurs, so we don't leak.  Untested, as I don't
> > have hardware.  I think its pretty straightforward, but please review closely.
> > 
> > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> 
> Applied, but please refer to commits in the form "$SHA1ID ("Commit message
> header line")", I fixed it up for you this time.
> 
copy, thanks dave
Neil