sfc: PTP: Moderate log message on event queue overflow

Limit syslog flood if a PTP packet storm occurs.

Fixes: 7c236c43b838 ('sfc: Add support for IEEE-1588 PTP')
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

diff --git a/drivers/net/ethernet/sfc/ptp.c b/drivers/net/ethernet/sfc/ptp.c
index 93a61a157d10219d1f48db671e59f7af2d4fd168..8b2cf783217cacd2d035545b90acd5712f4d2bc6 100644 (file)
--- a/drivers/net/ethernet/sfc/ptp.c
+++ b/drivers/net/ethernet/sfc/ptp.c
@@ -220,6 +220,7 @@ struct efx_ptp_timeset {
  * @evt_list: List of MC receive events awaiting packets
  * @evt_free_list: List of free events
  * @evt_lock: Lock for manipulating evt_list and evt_free_list
+ * @evt_overflow: Boolean indicating that event list has overflowed
  * @rx_evts: Instantiated events (on evt_list and evt_free_list)
  * @workwq: Work queue for processing pending PTP operations
  * @work: Work task
@@ -270,6 +271,7 @@ struct efx_ptp_data {
        struct list_head evt_list;
        struct list_head evt_free_list;
        spinlock_t evt_lock;
+       bool evt_overflow;
        struct efx_ptp_event_rx rx_evts[MAX_RECEIVE_EVENTS];
        struct workqueue_struct *workwq;
        struct work_struct work;
@@ -635,6 +637,11 @@ static void efx_ptp_drop_time_expired_events(struct efx_nic *efx)
                        }
                }
        }
+       /* If the event overflow flag is set and the event list is now empty
+        * clear the flag to re-enable the overflow warning message.
+        */
+       if (ptp->evt_overflow && list_empty(&ptp->evt_list))
+               ptp->evt_overflow = false;
        spin_unlock_bh(&ptp->evt_lock);
 }
 
@@ -676,6 +683,11 @@ static enum ptp_packet_state efx_ptp_match_rx(struct efx_nic *efx,
                        break;
                }
        }
+       /* If the event overflow flag is set and the event list is now empty
+        * clear the flag to re-enable the overflow warning message.
+        */
+       if (ptp->evt_overflow && list_empty(&ptp->evt_list))
+               ptp->evt_overflow = false;
        spin_unlock_bh(&ptp->evt_lock);
 
        return rc;
@@ -809,6 +821,7 @@ static int efx_ptp_stop(struct efx_nic *efx)
        list_for_each_safe(cursor, next, &efx->ptp_data->evt_list) {
                list_move(cursor, &efx->ptp_data->evt_free_list);
        }
+       ptp->evt_overflow = false;
        spin_unlock_bh(&efx->ptp_data->evt_lock);
 
        return rc;
@@ -901,6 +914,7 @@ static int efx_ptp_probe_channel(struct efx_channel *channel)
        spin_lock_init(&ptp->evt_lock);
        for (pos = 0; pos < MAX_RECEIVE_EVENTS; pos++)
                list_add(&ptp->rx_evts[pos].link, &ptp->evt_free_list);
+       ptp->evt_overflow = false;
 
        ptp->phc_clock_info.owner = THIS_MODULE;
        snprintf(ptp->phc_clock_info.name,
@@ -1299,8 +1313,13 @@ static void ptp_event_rx(struct efx_nic *efx, struct efx_ptp_data *ptp)
                list_add_tail(&evt->link, &ptp->evt_list);
 
                queue_work(ptp->workwq, &ptp->work);
-       } else {
-               netif_err(efx, rx_err, efx->net_dev, "No free PTP event");
+       } else if (!ptp->evt_overflow) {
+               /* Log a warning message and set the event overflow flag.
+                * The message won't be logged again until the event queue
+                * becomes empty.
+                */
+               netif_err(efx, rx_err, efx->net_dev, "PTP event queue overflow\n");
+               ptp->evt_overflow = true;
        }
        spin_unlock_bh(&ptp->evt_lock);
 }