i40e: check for Tx timestamp timeouts during watchdog

The i40e driver has logic to handle only one Tx timestamp at a time,
using a state bit lock to avoid multiple requests at once.

It may be possible, if incredibly unlikely, that a Tx timestamp event is
requested but never completes. Since we use an interrupt scheme to
determine when the Tx timestamp occurred we would never clear the state
bit in this case.

Add an i40e_ptp_tx_hang() function similar to the already existing
i40e_ptp_rx_hang() function. This function runs in the watchdog routine
and makes sure we eventually recover from this case instead of
permanently disabling Tx timestamps.

Note: there is no currently known way to cause this without hacking the
driver code to force it.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index f4465afe1fe1abc8d849127c20df7659a7e7f598..25bf336c5f380eca444cfd0a0b502b44654c27d6 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -502,6 +502,7 @@ struct i40e_pf {
        struct ptp_clock *ptp_clock;
        struct ptp_clock_info ptp_caps;
        struct sk_buff *ptp_tx_skb;
+       unsigned long ptp_tx_start;
        struct hwtstamp_config tstamp_config;
        struct mutex tmreg_lock; /* Used to protect the SYSTIME registers. */
        u64 ptp_base_adj;
@@ -957,6 +958,7 @@ bool i40e_dcb_need_reconfig(struct i40e_pf *pf,
                            struct i40e_dcbx_config *new_cfg);
 #endif /* CONFIG_I40E_DCB */
 void i40e_ptp_rx_hang(struct i40e_pf *pf);
+void i40e_ptp_tx_hang(struct i40e_pf *pf);
 void i40e_ptp_tx_hwtstamp(struct i40e_pf *pf);
 void i40e_ptp_rx_hwtstamp(struct i40e_pf *pf, struct sk_buff *skb, u8 index);
 void i40e_ptp_set_increment(struct i40e_pf *pf);

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index c019dec988e3f859d1f2621b69e4329552eb85a4..e4eb97832413ac564454c880fbafc8f50f35c750 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -6373,6 +6373,7 @@ static void i40e_watchdog_subtask(struct i40e_pf *pf)
        }
 
        i40e_ptp_rx_hang(pf);
+       i40e_ptp_tx_hang(pf);
 }
 
 /**

diff --git a/drivers/net/ethernet/intel/i40e/i40e_ptp.c b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
index cb81e16d0874b0bc7ed996e676c0789bf18dde95..1a0be835fa060882a8da1b987980a3e9a2cc8a8f 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_ptp.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
@@ -327,6 +327,36 @@ void i40e_ptp_rx_hang(struct i40e_pf *pf)
        pf->rx_hwtstamp_cleared += cleared;
 }
 
+/**
+ * i40e_ptp_tx_hang - Detect error case when Tx timestamp register is hung
+ * @pf: The PF private data structure
+ *
+ * This watchdog task is run periodically to make sure that we clear the Tx
+ * timestamp logic if we don't obtain a timestamp in a reasonable amount of
+ * time. It is unexpected in the normal case but if it occurs it results in
+ * permanently prevent timestamps of future packets
+ **/
+void i40e_ptp_tx_hang(struct i40e_pf *pf)
+{
+       if (!(pf->flags & I40E_FLAG_PTP) || !pf->ptp_tx)
+               return;
+
+       /* Nothing to do if we're not already waiting for a timestamp */
+       if (!test_bit(__I40E_PTP_TX_IN_PROGRESS, pf->state))
+               return;
+
+       /* We already have a handler routine which is run when we are notified
+        * of a Tx timestamp in the hardware. If we don't get an interrupt
+        * within a second it is reasonable to assume that we never will.
+        */
+       if (time_is_before_jiffies(pf->ptp_tx_start + HZ)) {
+               dev_kfree_skb_any(pf->ptp_tx_skb);
+               pf->ptp_tx_skb = NULL;
+               clear_bit_unlock(__I40E_PTP_TX_IN_PROGRESS, pf->state);
+               pf->tx_hwtstamp_timeouts++;
+       }
+}
+
 /**
  * i40e_ptp_tx_hwtstamp - Utility function which returns the Tx timestamp
  * @pf: Board private structure

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index c69ee4b0cfe22903ca19f7aa3217adbc651e6988..c2e9013d05eb7142949cbb1c9ecd8d4a623b1ca1 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -2628,6 +2628,7 @@ static int i40e_tsyn(struct i40e_ring *tx_ring, struct sk_buff *skb,
        if (pf->ptp_tx &&
            !test_and_set_bit_lock(__I40E_PTP_TX_IN_PROGRESS, pf->state)) {
                skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
+               pf->ptp_tx_start = jiffies;
                pf->ptp_tx_skb = skb_get(skb);
        } else {
                pf->tx_hwtstamp_skipped++;