igc: add lock preventing multiple simultaneous PTM transactions

Add a mutex around the PTM transaction to prevent multiple transactors

Multiple processes try to initiate a PTM transaction, one or all may
fail. This can be reproduced by running two instances of the
following:

$ sudo phc2sys -O 0 -i tsn0 -m

PHC2SYS exits with:

"ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
 fails

Note: Normally two instance of PHC2SYS will not run, but one process
 should not break another.

Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
Reviewed-by: Corinna Vinschen <vinschen@redhat.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index c35cc5cb1185695734c543b1bd181d7d838c487a..2f265c0959c7a01a23d6cb081e42ae3b208aab83 100644 (file)
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -319,6 +319,7 @@ struct igc_adapter {
        struct timespec64 prev_ptp_time; /* Pre-reset PTP clock */
        ktime_t ptp_reset_start; /* Reset time in clock mono */
        struct system_time_snapshot snapshot;
+       struct mutex ptm_lock; /* Only allow one PTM transaction at a time */
 
        char fw_version[32];
 

diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
index 343205bffc355022306bcb1db35109e2113bb430..612ed26a29c5d491cc3f2c2af803adc770d60fc2 100644 (file)
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -974,6 +974,7 @@ static void igc_ptm_log_error(struct igc_adapter *adapter, u32 ptm_stat)
        }
 }
 
+/* The PTM lock: adapter->ptm_lock must be held when calling igc_ptm_trigger() */
 static void igc_ptm_trigger(struct igc_hw *hw)
 {
        u32 ctrl;
@@ -990,6 +991,7 @@ static void igc_ptm_trigger(struct igc_hw *hw)
        wrfl();
 }
 
+/* The PTM lock: adapter->ptm_lock must be held when calling igc_ptm_reset() */
 static void igc_ptm_reset(struct igc_hw *hw)
 {
        u32 ctrl;
@@ -1068,9 +1070,16 @@ static int igc_ptp_getcrosststamp(struct ptp_clock_info *ptp,
 {
        struct igc_adapter *adapter = container_of(ptp, struct igc_adapter,
                                                   ptp_caps);
+       int ret;
 
-       return get_device_system_crosststamp(igc_phc_get_syncdevicetime,
-                                            adapter, &adapter->snapshot, cts);
+       /* This blocks until any in progress PTM transactions complete */
+       mutex_lock(&adapter->ptm_lock);
+
+       ret = get_device_system_crosststamp(igc_phc_get_syncdevicetime,
+                                           adapter, &adapter->snapshot, cts);
+       mutex_unlock(&adapter->ptm_lock);
+
+       return ret;
 }
 
 static int igc_ptp_getcyclesx64(struct ptp_clock_info *ptp,
@@ -1169,6 +1178,7 @@ void igc_ptp_init(struct igc_adapter *adapter)
        spin_lock_init(&adapter->ptp_tx_lock);
        spin_lock_init(&adapter->free_timer_lock);
        spin_lock_init(&adapter->tmreg_lock);
+       mutex_init(&adapter->ptm_lock);
 
        adapter->tstamp_config.rx_filter = HWTSTAMP_FILTER_NONE;
        adapter->tstamp_config.tx_type = HWTSTAMP_TX_OFF;
@@ -1181,6 +1191,7 @@ void igc_ptp_init(struct igc_adapter *adapter)
        if (IS_ERR(adapter->ptp_clock)) {
                adapter->ptp_clock = NULL;
                netdev_err(netdev, "ptp_clock_register failed\n");
+               mutex_destroy(&adapter->ptm_lock);
        } else if (adapter->ptp_clock) {
                netdev_info(netdev, "PHC added\n");
                adapter->ptp_flags |= IGC_PTP_ENABLED;
@@ -1210,10 +1221,12 @@ static void igc_ptm_stop(struct igc_adapter *adapter)
        struct igc_hw *hw = &adapter->hw;
        u32 ctrl;
 
+       mutex_lock(&adapter->ptm_lock);
        ctrl = rd32(IGC_PTM_CTRL);
        ctrl &= ~IGC_PTM_CTRL_EN;
 
        wr32(IGC_PTM_CTRL, ctrl);
+       mutex_unlock(&adapter->ptm_lock);
 }
 
 /**
@@ -1255,6 +1268,7 @@ void igc_ptp_stop(struct igc_adapter *adapter)
                netdev_info(adapter->netdev, "PHC removed\n");
                adapter->ptp_flags &= ~IGC_PTP_ENABLED;
        }
+       mutex_destroy(&adapter->ptm_lock);
 }
 
 /**
@@ -1294,6 +1308,7 @@ void igc_ptp_reset(struct igc_adapter *adapter)
                if (!igc_is_crosststamp_supported(adapter))
                        break;
 
+               mutex_lock(&adapter->ptm_lock);
                wr32(IGC_PCIE_DIG_DELAY, IGC_PCIE_DIG_DELAY_DEFAULT);
                wr32(IGC_PCIE_PHY_DELAY, IGC_PCIE_PHY_DELAY_DEFAULT);
 
@@ -1317,6 +1332,7 @@ void igc_ptp_reset(struct igc_adapter *adapter)
                        netdev_err(adapter->netdev, "Timeout reading IGC_PTM_STAT register\n");
 
                igc_ptm_reset(hw);
+               mutex_unlock(&adapter->ptm_lock);
                break;
        default:
                /* No work to do. */