qede: Handle infinite driver spinning for Tx timestamp.

In PTP Tx implementation, driver kept scheduling a poll thread until the
timestamp is available. In the error scenarios (e.g. app requesting the
timestamp for non-ptp packet), this thread kept waiting for the timestamp
forever.  This patch add changes to report such scenario as an error and
terminate the thread. Added a timeout of 2 seconds i.e., max time to wait
for Tx timestamp. Added a stat value ptp_skip_txts for reporting the number
of packets for which Tx timestamping is skipped.

Signed-off-by: Sudarsana Reddy Kalluru <skalluru@marvell.com>
Signed-off-by: Michal Kalderon <mkalderon@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/qede/qede.h

@@ -92,6 +92,7 @@ struct qede_stats_common {
 	u64 non_coalesced_pkts;
 	u64 coalesced_bytes;
 	u64 link_change_count;
+	u64 ptp_skip_txts;
 
 	/* port */
 	u64 rx_64_byte_packets;
@@ -189,6 +190,7 @@ struct qede_dev {
 
 	const struct qed_eth_ops	*ops;
 	struct qede_ptp			*ptp;
+	u64				ptp_skip_txts;
 
 	struct qed_dev_eth_info dev_info;
 #define QEDE_MAX_RSS_CNT(edev)	((edev)->dev_info.num_queues)

drivers/net/ethernet/qlogic/qede/qede_ethtool.c

@@ -174,6 +174,7 @@ static const struct {
 	QEDE_STAT(coalesced_bytes),
 
 	QEDE_STAT(link_change_count),
+	QEDE_STAT(ptp_skip_txts),
 };
 
 #define QEDE_NUM_STATS	ARRAY_SIZE(qede_stats_arr)

drivers/net/ethernet/qlogic/qede/qede_main.c

@@ -390,6 +390,7 @@ void qede_fill_by_demand_stats(struct qede_dev *edev)
 	p_common->brb_discards = stats.common.brb_discards;
 	p_common->tx_mac_ctrl_frames = stats.common.tx_mac_ctrl_frames;
 	p_common->link_change_count = stats.common.link_change_count;
+	p_common->ptp_skip_txts = edev->ptp_skip_txts;
 
 	if (QEDE_IS_BB(edev)) {
 		struct qede_stats_bb *p_bb = &edev->stats.bb;
@@ -2232,6 +2233,8 @@ static void qede_unload(struct qede_dev *edev, enum qede_unload_mode mode,
 	if (mode != QEDE_UNLOAD_RECOVERY)
 		DP_NOTICE(edev, "Link is down\n");
 
+	edev->ptp_skip_txts = 0;
+
 	DP_INFO(edev, "Ending qede unload\n");
 }
 

drivers/net/ethernet/qlogic/qede/qede_ptp.c

@@ -30,6 +30,7 @@
  * SOFTWARE.
  */
 #include "qede_ptp.h"
+#define QEDE_PTP_TX_TIMEOUT (2 * HZ)
 
 struct qede_ptp {
 	const struct qed_eth_ptp_ops	*ops;
@@ -38,6 +39,7 @@ struct qede_ptp {
 	struct timecounter		tc;
 	struct ptp_clock		*clock;
 	struct work_struct		work;
+	unsigned long			ptp_tx_start;
 	struct qede_dev			*edev;
 	struct sk_buff			*tx_skb;
 
@@ -160,18 +162,30 @@ static void qede_ptp_task(struct work_struct *work)
 	struct qede_dev *edev;
 	struct qede_ptp *ptp;
 	u64 timestamp, ns;
+	bool timedout;
 	int rc;
 
 	ptp = container_of(work, struct qede_ptp, work);
 	edev = ptp->edev;
+	timedout = time_is_before_jiffies(ptp->ptp_tx_start +
+					  QEDE_PTP_TX_TIMEOUT);
 
 	/* Read Tx timestamp registers */
 	spin_lock_bh(&ptp->lock);
 	rc = ptp->ops->read_tx_ts(edev->cdev, &timestamp);
 	spin_unlock_bh(&ptp->lock);
 	if (rc) {
-		/* Reschedule to keep checking for a valid timestamp value */
-		schedule_work(&ptp->work);
+		if (unlikely(timedout)) {
+			DP_INFO(edev, "Tx timestamp is not recorded\n");
+			dev_kfree_skb_any(ptp->tx_skb);
+			ptp->tx_skb = NULL;
+			clear_bit_unlock(QEDE_FLAGS_PTP_TX_IN_PRORGESS,
+					 &edev->flags);
+			edev->ptp_skip_txts++;
+		} else {
+			/* Reschedule to keep checking for a valid TS value */
+			schedule_work(&ptp->work);
+		}
 		return;
 	}
 
@@ -514,19 +528,28 @@ void qede_ptp_tx_ts(struct qede_dev *edev, struct sk_buff *skb)
 	if (!ptp)
 		return;
 
-	if (test_and_set_bit_lock(QEDE_FLAGS_PTP_TX_IN_PRORGESS, &edev->flags))
+	if (test_and_set_bit_lock(QEDE_FLAGS_PTP_TX_IN_PRORGESS,
+				  &edev->flags)) {
+		DP_ERR(edev, "Timestamping in progress\n");
+		edev->ptp_skip_txts++;
 		return;
+	}
 
 	if (unlikely(!test_bit(QEDE_FLAGS_TX_TIMESTAMPING_EN, &edev->flags))) {
-		DP_NOTICE(edev,
-			  "Tx timestamping was not enabled, this packet will not be timestamped\n");
+		DP_ERR(edev,
+		       "Tx timestamping was not enabled, this packet will not be timestamped\n");
+		clear_bit_unlock(QEDE_FLAGS_PTP_TX_IN_PRORGESS, &edev->flags);
+		edev->ptp_skip_txts++;
 	} else if (unlikely(ptp->tx_skb)) {
-		DP_NOTICE(edev,
-			  "The device supports only a single outstanding packet to timestamp, this packet will not be timestamped\n");
+		DP_ERR(edev,
+		       "The device supports only a single outstanding packet to timestamp, this packet will not be timestamped\n");
+		clear_bit_unlock(QEDE_FLAGS_PTP_TX_IN_PRORGESS, &edev->flags);
+		edev->ptp_skip_txts++;
 	} else {
 		skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
 		/* schedule check for Tx timestamp */
 		ptp->tx_skb = skb_get(skb);
+		ptp->ptp_tx_start = jiffies;
 		schedule_work(&ptp->work);
 	}
 }