Merge branch '100GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue

Tony Nguyen says:

====================
Intel Wired LAN Driver Updates 2021-12-14

This series contains updates to ice driver only.

Karol corrects division that was causing incorrect calculations and
adds a check to ensure stale timestamps are not being used.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/ice/ice_ptp.c

@@ -705,7 +705,7 @@ static int ice_ptp_adjfine(struct ptp_clock_info *info, long scaled_ppm)
 		scaled_ppm = -scaled_ppm;
 	}
 
-	while ((u64)scaled_ppm > div_u64(U64_MAX, incval)) {
+	while ((u64)scaled_ppm > div64_u64(U64_MAX, incval)) {
 		/* handle overflow by scaling down the scaled_ppm and
 		 * the divisor, losing some precision
 		 */
@@ -1540,19 +1540,16 @@ static void ice_ptp_tx_tstamp_work(struct kthread_work *work)
 		if (err)
 			continue;
 
-		/* Check if the timestamp is valid */
-		if (!(raw_tstamp & ICE_PTP_TS_VALID))
+		/* Check if the timestamp is invalid or stale */
+		if (!(raw_tstamp & ICE_PTP_TS_VALID) ||
+		    raw_tstamp == tx->tstamps[idx].cached_tstamp)
 			continue;
 
-		/* clear the timestamp register, so that it won't show valid
-		 * again when re-used.
-		 */
-		ice_clear_phy_tstamp(hw, tx->quad, phy_idx);
-
 		/* The timestamp is valid, so we'll go ahead and clear this
 		 * index and then send the timestamp up to the stack.
 		 */
 		spin_lock(&tx->lock);
+		tx->tstamps[idx].cached_tstamp = raw_tstamp;
 		clear_bit(idx, tx->in_use);
 		skb = tx->tstamps[idx].skb;
 		tx->tstamps[idx].skb = NULL;

drivers/net/ethernet/intel/ice/ice_ptp.h

@@ -55,15 +55,21 @@ struct ice_perout_channel {
  * struct ice_tx_tstamp - Tracking for a single Tx timestamp
  * @skb: pointer to the SKB for this timestamp request
  * @start: jiffies when the timestamp was first requested
+ * @cached_tstamp: last read timestamp
  *
  * This structure tracks a single timestamp request. The SKB pointer is
  * provided when initiating a request. The start time is used to ensure that
  * we discard old requests that were not fulfilled within a 2 second time
  * window.
+ * Timestamp values in the PHY are read only and do not get cleared except at
+ * hardware reset or when a new timestamp value is captured. The cached_tstamp
+ * field is used to detect the case where a new timestamp has not yet been
+ * captured, ensuring that we avoid sending stale timestamp data to the stack.
  */
 struct ice_tx_tstamp {
 	struct sk_buff *skb;
 	unsigned long start;
+	u64 cached_tstamp;
 };
 
 /**