From: Troy Kisky <troy.ki...@boundarydevices.com> Sent: Friday, April 22, 2016
10:01 AM
> To: netdev@vger.kernel.org; da...@davemloft.net; Fugang Duan
> <fugang.d...@nxp.com>; lzn...@gmail.com
> Cc: Fabio Estevam <fabio.este...@nxp.com>; l.st...@pengutronix.de;
> and...@lunn.ch; trem...@gmail.com; g...@uclinux.org; linux-arm-
> ker...@lists.infradead.org; johan...@sipsolutions.net;
> stillcompil...@gmail.com; sergei.shtyl...@cogentembedded.com;
> a...@arndb.de; holgerschu...@gmail.com; Troy Kisky
> <troy.ki...@boundarydevices.com>
> Subject: [PATCH net 1/1] net: fec: update dirty_tx even if no skb
>
> If dirty_tx isn't updated, then dma_unmap_single will be called twice.
>
> This fixes a
> [ 58.420980] ------------[ cut here ]------------
> [ 58.425667] WARNING: CPU: 0 PID: 377 at /home/schurig/d/mkarm/linux-
> 4.5/lib/dma-debug.c:1096 check_unmap+0x9d0/0xab8()
> [ 58.436405] fec 2188000.ethernet: DMA-API: device driver tries to free DMA
> memory it has not allocated [device address=0x0000000000000000] [size=66
> bytes]
>
> encountered by Holger
>
> Signed-off-by: Troy Kisky <troy.ki...@boundarydevices.com>
> Tested-by: <holgerschu...@gmail.com>
> ---
> drivers/net/ethernet/freescale/fec_main.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/ethernet/freescale/fec_main.c
> b/drivers/net/ethernet/freescale/fec_main.c
> index 08243c2..b71654c 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -1197,10 +1197,8 @@ fec_enet_tx_queue(struct net_device *ndev, u16
> queue_id)
> fec16_to_cpu(bdp->cbd_datlen),
> DMA_TO_DEVICE);
> bdp->cbd_bufaddr = cpu_to_fec32(0);
> - if (!skb) {
> - bdp = fec_enet_get_nextdesc(bdp, &txq->bd);
> - continue;
> - }
> + if (!skb)
> + goto skb_done;
>
> /* Check for errors. */
> if (status & (BD_ENET_TX_HB | BD_ENET_TX_LC | @@ -1239,7
> +1237,7 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id)
>
> /* Free the sk buffer associated with this last transmit */
> dev_kfree_skb_any(skb);
> -
> +skb_done:
> /* Make sure the update to bdp and tx_skbuff are performed
> * before dirty_tx
> */
> --
> 2.5.0
The patch is fine for me.
Can you review below patch that also fix the issue. It can take much effort due
to less rmb() and READ_ONCE() operation that is very sensitive for duplex Gbps
test for i.MX6SX/i.MX7d SOC. (i.MX6SX can reach at 1.4Gbps, i.MX7D can reach at
1.8Gbps.)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1160,12 +1160,13 @@ static void
fec_enet_tx_queue(struct net_device *ndev, u16 queue_id)
{
struct fec_enet_private *fep;
- struct bufdesc *bdp;
+ struct bufdesc *bdp, *bdp_t;
unsigned short status;
struct sk_buff *skb;
struct fec_enet_priv_tx_q *txq;
struct netdev_queue *nq;
int index = 0;
+ int i, bdnum;
int entries_free;
fep = netdev_priv(ndev);
@@ -1187,20 +1188,28 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id)
if (status & BD_ENET_TX_READY)
break;
- index = fec_enet_get_bd_index(bdp, &txq->bd);
-
+ bdp_t = bdp;
+ bdnum = 1;
+ index = fec_enet_get_bd_index(txq->tx_bd_base, bdp_t, fep);
skb = txq->tx_skbuff[index];
- txq->tx_skbuff[index] = NULL;
- if (!IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr)))
- dma_unmap_single(&fep->pdev->dev,
- fec32_to_cpu(bdp->cbd_bufaddr),
- fec16_to_cpu(bdp->cbd_datlen),
- DMA_TO_DEVICE);
- bdp->cbd_bufaddr = cpu_to_fec32(0);
- if (!skb) {
- bdp = fec_enet_get_nextdesc(bdp, &txq->bd);
- continue;
+ while (!skb) {
+ bdp_t = fec_enet_get_nextdesc(bdp_t, &txq->bd);
+ index = fec_enet_get_bd_index(txq->tx_bd_base, bdp_t,
fep);
+ skb = txq->tx_skbuff[index];
+ bdnum++;
+ }
+ status = fec16_to_cpu(READ_ONCE(bdp->cbd_sc));
+ if (status & BD_ENET_TX_READY)
+ break;
+
+ for (i = 0; i < bdnum; i++) {
+ if (!IS_TSO_HEADER(txq, bdp->cbd_bufaddr))
+ dma_unmap_single(&fep->pdev->dev,
bdp->cbd_bufaddr,
+ bdp->cbd_datlen,
DMA_TO_DEVICE);
+ bdp->cbd_bufaddr = 0;
+ if (i < bdnum - 1)
+ bdp = fec_enet_get_nextdesc(bdp, &txq->bd);
}
+ txq->tx_skbuff[index] = NULL;
Regards,
Andy
