[PATCH v2 net-next 09/14] net: enetc: save the parsed information of PTP packet to skb->cb

[Wei Fang <wei.fang@nxp.com>]

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, we add struct enetc_skb_cb as the format of the data
in the skb->cb buffer to save the parsed information of PTP packet.

In addition, the variables offset1 and offset2 in enetc_map_tx_buffs()
are renamed to corr_off and tstamp_off to make them easier to understand.

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

---
v2 changes:
1. Add description of offset1 and offset2 being renamed in the commit
message.
---
 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..c1373163a096 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