e1000e: add timeout for TX HW time stamping work

Hardware may fail to report time stamp e.g.:
 - when hardware time stamping is not enabled
 - when time stamp is requested shortly after ifup

Timeout time stamp reading work to prevent it from
scheduling itself indefinitely. Report timeout events
via system log and device stats.

Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

3 files changed, 10 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/e1000e/e1000.h b/drivers/net/ethernet/intel/e1000e/e1000.h
index 5325e3e2154e..1471c5464a89 100644
--- a/drivers/net/ethernet/intel/e1000e/e1000.h
+++ b/drivers/net/ethernet/intel/e1000e/e1000.h
@@ -262,6 +262,7 @@ struct e1000_adapter {
         u32 tx_head_addr;
         u32 tx_fifo_size;
         u32 tx_dma_failed;
+        u32 tx_hwtstamp_timeouts;
 
         /* Rx */
         bool (*clean_rx) (struct e1000_ring *ring, int *work_done,
@@ -334,6 +335,7 @@ struct e1000_adapter {
         struct hwtstamp_config hwtstamp_config;
         struct delayed_work systim_overflow_work;
         struct sk_buff *tx_hwtstamp_skb;
+        unsigned long tx_hwtstamp_start;
         struct work_struct tx_hwtstamp_work;
         spinlock_t systim_lock; /* protects SYSTIML/H regsters */
         struct cyclecounter cc;
diff --git a/drivers/net/ethernet/intel/e1000e/ethtool.c b/drivers/net/ethernet/intel/e1000e/ethtool.c
index 3c2898d0c2aa..cad250bc1b99 100644
--- a/drivers/net/ethernet/intel/e1000e/ethtool.c
+++ b/drivers/net/ethernet/intel/e1000e/ethtool.c
@@ -104,6 +104,7 @@ static const struct e1000_stats e1000_gstrings_stats[] = {
         E1000_STAT("rx_hwtstamp_cleared", rx_hwtstamp_cleared),
         E1000_STAT("uncorr_ecc_errors", uncorr_errors),
         E1000_STAT("corr_ecc_errors", corr_errors),
+        E1000_STAT("tx_hwtstamp_timeouts", tx_hwtstamp_timeouts),
 };
 
 #define E1000_GLOBAL_STATS_LEN  ARRAY_SIZE(e1000_gstrings_stats)
diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 6bd1832e3f3e..b8d252fcad18 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -1163,6 +1163,12 @@ static void e1000e_tx_hwtstamp_work(struct work_struct *work)
                 skb_tstamp_tx(adapter->tx_hwtstamp_skb, &shhwtstamps);
                 dev_kfree_skb_any(adapter->tx_hwtstamp_skb);
                 adapter->tx_hwtstamp_skb = NULL;
+        } else if (time_after(jiffies, adapter->tx_hwtstamp_start
+                              + adapter->tx_timeout_factor * HZ)) {
+                dev_kfree_skb_any(adapter->tx_hwtstamp_skb);
+                adapter->tx_hwtstamp_skb = NULL;
+                adapter->tx_hwtstamp_timeouts++;
+                e_warn("clearing Tx timestamp hang");
         } else {
                 /* reschedule to check later */
                 schedule_work(&adapter->tx_hwtstamp_work);
@@ -5567,6 +5573,7 @@ static netdev_tx_t e1000_xmit_frame(struct sk_buff *skb,
                         skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
                         tx_flags |= E1000_TX_FLAGS_HWTSTAMP;
                         adapter->tx_hwtstamp_skb = skb_get(skb);
+                        adapter->tx_hwtstamp_start = jiffies;
                         schedule_work(&adapter->tx_hwtstamp_work);
                 } else {
                         skb_tx_timestamp(skb);