[PATCH v3 net-next 10/15] net: enetc: save the parsed information of PTP packet to skb->cb

Wei Fang
2025-08-12T10:08:10Z

Currently, the Tx PTP packets are parsed twice in the enetc driver, once
in enetc_xmit() and once in enetc_map_tx_buffs(). The latter is duplicate
and is unnecessary, since the parsed information can be saved to skb->cb
so that enetc_map_tx_buffs() can get the previously parsed data from
skb->cb. Therefore, add struct enetc_skb_cb as the format of the data
in the skb->cb buffer to save the parsed information of PTP packet. Use
saved information in enetc_map_tx_buffs() to avoid parsing data again.

In addition, rename variables offset1 and offset2 in enetc_map_tx_buffs()
to corr_off and tstamp_off for better readability.

Signed-off-by: Wei Fang <wei.fang@nxp.com>

---
v2 changes:
1. Add description of offset1 and offset2 being renamed in the commit
message.
v3 changes:
1. Improve the commit message
2. Fix the error the patch, there were two "++" in the patch
---
drivers/net/ethernet/freescale/enetc/enetc.c | 65 ++++++++++----------
drivers/net/ethernet/freescale/enetc/enetc.h | 9 +++
2 files changed, 43 insertions(+), 31 deletions(-)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
index e4287725832e..54ccd7c57961 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c
@@ -225,13 +225,12 @@ static int enetc_map_tx_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb)
{
bool do_vlan, do_onestep_tstamp = false, do_twostep_tstamp = false;
struct enetc_ndev_priv *priv = netdev_priv(tx_ring->ndev);
+ struct enetc_skb_cb *enetc_cb = ENETC_SKB_CB(skb);
struct enetc_hw *hw = &priv->si->hw;
struct enetc_tx_swbd *tx_swbd;
int len = skb_headlen(skb);
union enetc_tx_bd temp_bd;
- u8 msgtype, twostep, udp;
union enetc_tx_bd *txbd;
- u16 offset1, offset2;
int i, count = 0;
skb_frag_t *frag;
unsigned int f;
@@ -280,16 +279,10 @@ static int enetc_map_tx_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb)
count++;

do_vlan = skb_vlan_tag_present(skb);
- if (skb->cb[0] & ENETC_F_TX_ONESTEP_SYNC_TSTAMP) {
- if (enetc_ptp_parse(skb, &udp, &msgtype, &twostep, &offset1,
- &offset2) ||
- msgtype != PTP_MSGTYPE_SYNC || twostep)
- WARN_ONCE(1, "Bad packet for one-step timestamping\n");
- else
- do_onestep_tstamp = true;
- } else if (skb->cb[0] & ENETC_F_TX_TSTAMP) {
+ if (enetc_cb->flag & ENETC_F_TX_ONESTEP_SYNC_TSTAMP)
+ do_onestep_tstamp = true;
+ else if (enetc_cb->flag & ENETC_F_TX_TSTAMP)
do_twostep_tstamp = true;
- }

tx_swbd->do_twostep_tstamp = do_twostep_tstamp;
tx_swbd->qbv_en = !!(priv->active_offloads & ENETC_F_QBV);
@@ -333,6 +326,8 @@ static int enetc_map_tx_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb)
}

if (do_onestep_tstamp) {
+ u16 tstamp_off = enetc_cb->origin_tstamp_off;
+ u16 corr_off = enetc_cb->correction_off;
__be32 new_sec_l, new_nsec;
u32 lo, hi, nsec, val;
__be16 new_sec_h;
@@ -362,32 +357,32 @@ static int enetc_map_tx_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb)
new_sec_h = htons((sec >> 32) & 0xffff);
new_sec_l = htonl(sec & 0xffffffff);
new_nsec = htonl(nsec);
- if (udp) {
+ if (enetc_cb->udp) {
struct udphdr *uh = udp_hdr(skb);
__be32 old_sec_l, old_nsec;
__be16 old_sec_h;

- old_sec_h = *(__be16 *)(data + offset2);
+ old_sec_h = *(__be16 *)(data + tstamp_off);
inet_proto_csum_replace2(&uh->check, skb, old_sec_h,
new_sec_h, false);

- old_sec_l = *(__be32 *)(data + offset2 + 2);
+ old_sec_l = *(__be32 *)(data + tstamp_off + 2);
inet_proto_csum_replace4(&uh->check, skb, old_sec_l,
new_sec_l, false);

- old_nsec = *(__be32 *)(data + offset2 + 6);
+ old_nsec = *(__be32 *)(data + tstamp_off + 6);
inet_proto_csum_replace4(&uh->check, skb, old_nsec,
new_nsec, false);
}

- *(__be16 *)(data + offset2) = new_sec_h;
- *(__be32 *)(data + offset2 + 2) = new_sec_l;
- *(__be32 *)(data + offset2 + 6) = new_nsec;
+ *(__be16 *)(data + tstamp_off) = new_sec_h;
+ *(__be32 *)(data + tstamp_off + 2) = new_sec_l;
+ *(__be32 *)(data + tstamp_off + 6) = new_nsec;

/* Configure single-step register */
val = ENETC_PM0_SINGLE_STEP_EN;
- val |= ENETC_SET_SINGLE_STEP_OFFSET(offset1);
- if (udp)
+ val |= ENETC_SET_SINGLE_STEP_OFFSET(corr_off);
+ if (enetc_cb->udp)
val |= ENETC_PM0_SINGLE_STEP_CH;

enetc_port_mac_wr(priv->si, ENETC_PM0_SINGLE_STEP,
@@ -938,12 +933,13 @@ static int enetc_map_tx_tso_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb
static netdev_tx_t enetc_start_xmit(struct sk_buff *skb,
struct net_device *ndev)
{
+ struct enetc_skb_cb *enetc_cb = ENETC_SKB_CB(skb);
struct enetc_ndev_priv *priv = netdev_priv(ndev);
struct enetc_bdr *tx_ring;
int count;

/* Queue one-step Sync packet if already locked */
- if (skb->cb[0] & ENETC_F_TX_ONESTEP_SYNC_TSTAMP) {
+ if (enetc_cb->flag & ENETC_F_TX_ONESTEP_SYNC_TSTAMP) {
if (test_and_set_bit_lock(ENETC_TX_ONESTEP_TSTAMP_IN_PROGRESS,
&priv->flags)) {
skb_queue_tail(&priv->tx_skbs, skb);
@@ -1005,24 +1001,29 @@ static netdev_tx_t enetc_start_xmit(struct sk_buff *skb,

netdev_tx_t enetc_xmit(struct sk_buff *skb, struct net_device *ndev)
{
+ struct enetc_skb_cb *enetc_cb = ENETC_SKB_CB(skb);
struct enetc_ndev_priv *priv = netdev_priv(ndev);
u8 udp, msgtype, twostep;
u16 offset1, offset2;

- /* Mark tx timestamp type on skb->cb[0] if requires */
+ /* Mark tx timestamp type on enetc_cb->flag if requires */
if ((skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) &&
- (priv->active_offloads & ENETC_F_TX_TSTAMP_MASK)) {
- skb->cb[0] = priv->active_offloads & ENETC_F_TX_TSTAMP_MASK;
- } else {
- skb->cb[0] = 0;
- }
+ (priv->active_offloads & ENETC_F_TX_TSTAMP_MASK))
+ enetc_cb->flag = priv->active_offloads & ENETC_F_TX_TSTAMP_MASK;
+ else
+ enetc_cb->flag = 0;

/* Fall back to two-step timestamp if not one-step Sync packet */
- if (skb->cb[0] & ENETC_F_TX_ONESTEP_SYNC_TSTAMP) {
+ if (enetc_cb->flag & ENETC_F_TX_ONESTEP_SYNC_TSTAMP) {
if (enetc_ptp_parse(skb, &udp, &msgtype, &twostep,
&offset1, &offset2) ||
- msgtype != PTP_MSGTYPE_SYNC || twostep != 0)
- skb->cb[0] = ENETC_F_TX_TSTAMP;
+ msgtype != PTP_MSGTYPE_SYNC || twostep != 0) {
+ enetc_cb->flag = ENETC_F_TX_TSTAMP;
+ } else {
+ enetc_cb->udp = !!udp;
+ enetc_cb->correction_off = offset1;
+ enetc_cb->origin_tstamp_off = offset2;
+ }
}

return enetc_start_xmit(skb, ndev);
@@ -1214,7 +1215,9 @@ static bool enetc_clean_tx_ring(struct enetc_bdr *tx_ring, int napi_budget)
if (xdp_frame) {
xdp_return_frame(xdp_frame);
} else if (skb) {
- if (unlikely(skb->cb[0] & ENETC_F_TX_ONESTEP_SYNC_TSTAMP)) {
+ struct enetc_skb_cb *enetc_cb = ENETC_SKB_CB(skb);
+
+ if (unlikely(enetc_cb->flag & ENETC_F_TX_ONESTEP_SYNC_TSTAMP)) {
/* Start work to release lock for next one-step
* timestamping packet. And send one skb in
* tx_skbs queue if has.
diff --git a/drivers/net/ethernet/freescale/enetc/enetc.h b/drivers/net/ethernet/freescale/enetc/enetc.h
index 62e8ee4d2f04..ce3fed95091b 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.h
+++ b/drivers/net/ethernet/freescale/enetc/enetc.h
@@ -54,6 +54,15 @@ struct enetc_tx_swbd {
u8 qbv_en:1;
};

+struct enetc_skb_cb {
+ u8 flag;
+ bool udp;
+ u16 correction_off;
+ u16 origin_tstamp_off;
+};
+
+#define ENETC_SKB_CB(skb) ((struct enetc_skb_cb *)((skb)->cb))
+
struct enetc_lso_t {
bool ipv6;
bool tcp;
--
2.34.1