On Wed, Feb 19, 2025 at 01:42:40PM +0800, Wei Fang wrote:
> When creating a TSO header, if the skb is VLAN tagged, the extended BD
> will be used and the 'count' should be increased by 2 instead of 1.
> Otherwise, when an error occurs, less tx_swbd will be freed than the
> actual number.
>
> Fixes: fb8629e2cbfc ("net: enetc: add support for software TSO")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Wei Fang <wei.fang@xxxxxxx>
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@xxxxxxxxxxxxxxx>
> ---
I'm not sure "correct the statistics" is the best way to describe this
change. Maybe "keep track of correct TXBD count in enetc_map_tx_tso_buffs()"?
The bug is that not all TX buffers are freed on error, not that some
statistics are wrong.
> drivers/net/ethernet/freescale/enetc/enetc.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
> index 01c09fd26f9f..0658c06a23c1 100644
> --- a/drivers/net/ethernet/freescale/enetc/enetc.c
> +++ b/drivers/net/ethernet/freescale/enetc/enetc.c
> @@ -759,6 +759,7 @@ static int enetc_lso_hw_offload(struct enetc_bdr *tx_ring, struct sk_buff *skb)
> static int enetc_map_tx_tso_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb)
> {
> struct enetc_ndev_priv *priv = netdev_priv(tx_ring->ndev);
> + bool ext_bd = skb_vlan_tag_present(skb);
> int hdr_len, total_len, data_len;
> struct enetc_tx_swbd *tx_swbd;
> union enetc_tx_bd *txbd;
> @@ -792,7 +793,7 @@ static int enetc_map_tx_tso_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb
> csum = enetc_tso_hdr_csum(&tso, skb, hdr, hdr_len, &pos);
> enetc_map_tx_tso_hdr(tx_ring, skb, tx_swbd, txbd, &i, hdr_len, data_len);
> bd_data_num = 0;
> - count++;
> + count += ext_bd ? 2 : 1;
>
> while (data_len > 0) {
> int size;
> --
> 2.34.1
>
stylistic nitpick: I think this implementation choice obscures the fact,
to an unfamiliar reader, that the requirement for an extended TXBD comes
from enetc_map_tx_tso_hdr(). This is because you repeat the condition
for skb_vlan_tag_present(), but it's not obvious it's correlated to the
other one. Something like the change below is more expressive in this
regard, in my opinion:
diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
index fe3967268a19..6178157611db 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c
@@ -410,14 +410,15 @@ static int enetc_map_tx_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb)
return 0;
}
-static void enetc_map_tx_tso_hdr(struct enetc_bdr *tx_ring, struct sk_buff *skb,
- struct enetc_tx_swbd *tx_swbd,
- union enetc_tx_bd *txbd, int *i, int hdr_len,
- int data_len)
+static int enetc_map_tx_tso_hdr(struct enetc_bdr *tx_ring, struct sk_buff *skb,
+ struct enetc_tx_swbd *tx_swbd,
+ union enetc_tx_bd *txbd, int *i, int hdr_len,
+ int data_len)
{
union enetc_tx_bd txbd_tmp;
u8 flags = 0, e_flags = 0;
dma_addr_t addr;
+ int count = 1;
enetc_clear_tx_bd(&txbd_tmp);
addr = tx_ring->tso_headers_dma + *i * TSO_HEADER_SIZE;
@@ -460,7 +461,10 @@ static void enetc_map_tx_tso_hdr(struct enetc_bdr *tx_ring, struct sk_buff *skb,
/* Write the BD */
txbd_tmp.ext.e_flags = e_flags;
*txbd = txbd_tmp;
+ count++;
}
+
+ return count;
}
static int enetc_map_tx_tso_data(struct enetc_bdr *tx_ring, struct sk_buff *skb,
@@ -786,7 +790,6 @@ static int enetc_lso_hw_offload(struct enetc_bdr *tx_ring, struct sk_buff *skb)
static int enetc_map_tx_tso_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb)
{
struct enetc_ndev_priv *priv = netdev_priv(tx_ring->ndev);
- bool ext_bd = skb_vlan_tag_present(skb);
int hdr_len, total_len, data_len;
struct enetc_tx_swbd *tx_swbd;
union enetc_tx_bd *txbd;
@@ -818,9 +821,9 @@ static int enetc_map_tx_tso_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb
/* compute the csum over the L4 header */
csum = enetc_tso_hdr_csum(&tso, skb, hdr, hdr_len, &pos);
- enetc_map_tx_tso_hdr(tx_ring, skb, tx_swbd, txbd, &i, hdr_len, data_len);
+ count += enetc_map_tx_tso_hdr(tx_ring, skb, tx_swbd, txbd, &i,
+ hdr_len, data_len);
bd_data_num = 0;
- count += ext_bd ? 2 : 1;
while (data_len > 0) {
int size;
