bnxt_en: Remove atomic operations on ptp->tx_avail

Now that we require the spinlock to protect ptp->txts_prod, change
ptp->tx_avail to non-atomic and protect it under the same spinlock.
Add a new helper function bnxt_ptp_get_txts_prod() to decrement
ptp->tx_avail under spinlock and return the producer.
Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -519,34 +519,20 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		} else if (!skb_is_gso(skb)) {
 			u16 seq_id, hdr_off;
 
-			if (atomic_dec_if_positive(&ptp->tx_avail) < 0) {
-				atomic64_inc(&ptp->stats.ts_err);
-				goto tx_no_ts;
-			}
-
-			if (!bnxt_ptp_parse(skb, &seq_id, &hdr_off)) {
+			if (!bnxt_ptp_parse(skb, &seq_id, &hdr_off) &&
+			    !bnxt_ptp_get_txts_prod(ptp, &txts_prod)) {
 				if (vlan_tag_flags)
 					hdr_off += VLAN_HLEN;
 				lflags |= cpu_to_le32(TX_BD_FLAGS_STAMP);
 				tx_buf->is_ts_pkt = 1;
 				skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
 
-				spin_lock_bh(&ptp->ptp_tx_lock);
-				txts_prod = ptp->txts_prod;
-				ptp->txts_prod = NEXT_TXTS(txts_prod);
-				spin_unlock_bh(&ptp->ptp_tx_lock);
-
 				ptp->txts_req[txts_prod].tx_seqid = seq_id;
 				ptp->txts_req[txts_prod].tx_hdr_off = hdr_off;
 				tx_buf->txts_prod = txts_prod;
-
-			} else {
-				atomic_inc(&bp->ptp_cfg->tx_avail);
 			}
 		}
 	}
-
-tx_no_ts:
 	if (unlikely(skb->no_fcs))
 		lflags |= cpu_to_le32(TX_BD_FLAGS_NO_CRC);
 
@@ -12183,7 +12169,7 @@ static int __bnxt_open_nic(struct bnxt *bp, bool irq_re_init, bool link_re_init)
 	if (BNXT_PF(bp))
 		bnxt_vf_reps_open(bp);
 	if (bp->ptp_cfg && !(bp->fw_cap & BNXT_FW_CAP_TX_TS_CMP))
-		atomic_set(&bp->ptp_cfg->tx_avail, BNXT_MAX_TX_TS);
+		WRITE_ONCE(bp->ptp_cfg->tx_avail, BNXT_MAX_TX_TS);
 	bnxt_ptp_init_rtc(bp, true);
 	bnxt_ptp_cfg_tstamp_filters(bp);
 	if (BNXT_SUPPORTS_MULTI_RSS_CTX(bp))

drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c

@@ -730,10 +730,10 @@ static long bnxt_ptp_ts_aux_work(struct ptp_clock_info *ptp_info)
 	unsigned long now = jiffies;
 	struct bnxt *bp = ptp->bp;
 	u16 cons = ptp->txts_cons;
-	u8 num_requests;
+	u32 num_requests;
 	int rc = 0;
 
-	num_requests = BNXT_MAX_TX_TS - atomic_read(&ptp->tx_avail);
+	num_requests = BNXT_MAX_TX_TS - READ_ONCE(ptp->tx_avail);
 	while (num_requests--) {
 		if (IS_ERR(ptp->txts_req[cons].tx_skb))
 			goto next_slot;
@@ -743,7 +743,7 @@ static long bnxt_ptp_ts_aux_work(struct ptp_clock_info *ptp_info)
 		if (rc == -EAGAIN)
 			break;
 next_slot:
-		atomic_inc(&ptp->tx_avail);
+		BNXT_PTP_INC_TX_AVAIL(ptp);
 		cons = NEXT_TXTS(cons);
 	}
 	ptp->txts_cons = cons;
@@ -767,6 +767,21 @@ static long bnxt_ptp_ts_aux_work(struct ptp_clock_info *ptp_info)
 	return HZ;
 }
 
+int bnxt_ptp_get_txts_prod(struct bnxt_ptp_cfg *ptp, u16 *prod)
+{
+	spin_lock_bh(&ptp->ptp_tx_lock);
+	if (ptp->tx_avail) {
+		*prod = ptp->txts_prod;
+		ptp->txts_prod = NEXT_TXTS(*prod);
+		ptp->tx_avail--;
+		spin_unlock_bh(&ptp->ptp_tx_lock);
+		return 0;
+	}
+	spin_unlock_bh(&ptp->ptp_tx_lock);
+	atomic64_inc(&ptp->stats.ts_err);
+	return -ENOSPC;
+}
+
 void bnxt_get_tx_ts_p5(struct bnxt *bp, struct sk_buff *skb, u16 prod)
 {
 	struct bnxt_ptp_cfg *ptp = bp->ptp_cfg;
@@ -1014,7 +1029,7 @@ int bnxt_ptp_init(struct bnxt *bp, bool phc_cfg)
 
 	bnxt_ptp_free(bp);
 
-	atomic_set(&ptp->tx_avail, BNXT_MAX_TX_TS);
+	WRITE_ONCE(ptp->tx_avail, BNXT_MAX_TX_TS);
 	spin_lock_init(&ptp->ptp_lock);
 	spin_lock_init(&ptp->ptp_tx_lock);
 

drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.h

@@ -116,7 +116,7 @@ struct bnxt_ptp_cfg {
 	struct bnxt_ptp_tx_req	txts_req[BNXT_MAX_TX_TS];
 
 	struct bnxt		*bp;
-	atomic_t		tx_avail;
+	u32			tx_avail;
 	u16			rxctl;
 #define BNXT_PTP_MSG_SYNC			(1 << 0)
 #define BNXT_PTP_MSG_DELAY_REQ			(1 << 1)
@@ -157,6 +157,13 @@ do {						\
 	((dst) = READ_ONCE(src))
 #endif
 
+#define BNXT_PTP_INC_TX_AVAIL(ptp)		\
+do {						\
+	spin_lock_bh(&(ptp)->ptp_tx_lock);	\
+	(ptp)->tx_avail++;			\
+	spin_unlock_bh(&(ptp)->ptp_tx_lock);	\
+} while (0)
+
 int bnxt_ptp_parse(struct sk_buff *skb, u16 *seq_id, u16 *hdr_off);
 void bnxt_ptp_update_current_time(struct bnxt *bp);
 void bnxt_ptp_pps_event(struct bnxt *bp, u32 data1, u32 data2);
@@ -164,6 +171,7 @@ int bnxt_ptp_cfg_tstamp_filters(struct bnxt *bp);
 void bnxt_ptp_reapply_pps(struct bnxt *bp);
 int bnxt_hwtstamp_set(struct net_device *dev, struct ifreq *ifr);
 int bnxt_hwtstamp_get(struct net_device *dev, struct ifreq *ifr);
+int bnxt_ptp_get_txts_prod(struct bnxt_ptp_cfg *ptp, u16 *prod);
 void bnxt_get_tx_ts_p5(struct bnxt *bp, struct sk_buff *skb, u16 prod);
 int bnxt_get_rx_ts_p5(struct bnxt *bp, u64 *ts, u32 pkt_ts);
 void bnxt_tx_ts_cmp(struct bnxt *bp, struct bnxt_napi *bnapi,