Re: [PATCH] wan/fsl_ucc_hdlc: Fix size used in dma_free_coherent()

From: Christophe LEROY
Date: Sat Oct 08 2016 - 03:20:49 EST




Le 07/10/2016 à 22:58, Christophe JAILLET a écrit :
Size used with 'dma_alloc_coherent()' and 'dma_free_coherent()' should be
consistent.
Here, the size of a pointer is used in dma_alloc... and the size of the
pointed structure is used in dma_free...

This has been spotted with coccinelle, using the following script:
////////////////////
@r@
expression x0, x1, y0, y1, z0, z1, t0, t1, ret;
@@

* ret = dma_alloc_coherent(x0, y0, z0, t0);
...
* dma_free_coherent(x1, y1, ret, t1);


@script:python@
y0 << r.y0;
y1 << r.y1;

@@
if y1.find(y0) == -1:
print "WARNING: sizes look different: '%s' vs '%s'" % (y0, y1)
////////////////////

Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
---
Untested

I don't think the error is in the dma_free_coherent() calls.

The issue is for me in the dma_alloc_coherent() call. This call is supposed to allocate a table of buffer descriptors, not a table of pointers to BDs.

Later in the code, this is used the following way:

iowrite16be(bd_status, &priv->rx_bd_base[i].status);

So it is the allocation which should be

priv->rx_bd_base = dma_alloc_coherent(priv->dev,
RX_BD_RING_LEN * sizeof(struct qe_bd),
&priv->dma_rx_bd, GFP_KERNEL);

Christophe

---
drivers/net/wan/fsl_ucc_hdlc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wan/fsl_ucc_hdlc.c b/drivers/net/wan/fsl_ucc_hdlc.c
index 5fbf83d5aa57..65647533b401 100644
--- a/drivers/net/wan/fsl_ucc_hdlc.c
+++ b/drivers/net/wan/fsl_ucc_hdlc.c
@@ -295,11 +295,11 @@ static int uhdlc_init(struct ucc_hdlc_private *priv)
qe_muram_free(priv->ucc_pram_offset);
free_tx_bd:
dma_free_coherent(priv->dev,
- TX_BD_RING_LEN * sizeof(struct qe_bd),
+ TX_BD_RING_LEN * sizeof(struct qe_bd *),
priv->tx_bd_base, priv->dma_tx_bd);
free_rx_bd:
dma_free_coherent(priv->dev,
- RX_BD_RING_LEN * sizeof(struct qe_bd),
+ RX_BD_RING_LEN * sizeof(struct qe_bd *),
priv->rx_bd_base, priv->dma_rx_bd);
free_uccf:
ucc_fast_free(priv->uccf);
@@ -688,7 +688,7 @@ static void uhdlc_memclean(struct ucc_hdlc_private *priv)

if (priv->rx_bd_base) {
dma_free_coherent(priv->dev,
- RX_BD_RING_LEN * sizeof(struct qe_bd),
+ RX_BD_RING_LEN * sizeof(struct qe_bd *),
priv->rx_bd_base, priv->dma_rx_bd);

priv->rx_bd_base = NULL;
@@ -697,7 +697,7 @@ static void uhdlc_memclean(struct ucc_hdlc_private *priv)

if (priv->tx_bd_base) {
dma_free_coherent(priv->dev,
- TX_BD_RING_LEN * sizeof(struct qe_bd),
+ TX_BD_RING_LEN * sizeof(struct qe_bd *),
priv->tx_bd_base, priv->dma_tx_bd);

priv->tx_bd_base = NULL;