ixgbe: fix lockdep annotation issue for ptp's work item

This patch fixes a lockdep issue created due to ixgbe_ptp_stop always running
cancel_work_sync even if the work item had not been created properly with
INIT_WORK. This is caused because ixgbe_ptp_stop did not check to actually
ensure PTP was running first. The new implementation introduces a state in the
&adapter->state field which is used to indicate that PTP is running. (This
replaces the IXGBE_FLAG2_PTP_ENABLED field). This state will use the atomic
set_bit, test_bit, and test_and_clear_bit functions. ixgbe_ptp_stop will check
to ensure that PTP was enabled, (and if not, it will not attempt to do any
cleanup work from ixgbe_ptp_init). This resolves the lockdep annotation warning
found by Stephen Hemminger

Reported-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Acked-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe.h

@@ -618,9 +618,8 @@ struct ixgbe_adapter {
 #define IXGBE_FLAG2_FDIR_REQUIRES_REINIT        (u32)(1 << 7)
 #define IXGBE_FLAG2_RSS_FIELD_IPV4_UDP		(u32)(1 << 8)
 #define IXGBE_FLAG2_RSS_FIELD_IPV6_UDP		(u32)(1 << 9)
-#define IXGBE_FLAG2_PTP_ENABLED			(u32)(1 << 10)
-#define IXGBE_FLAG2_PTP_PPS_ENABLED		(u32)(1 << 11)
-#define IXGBE_FLAG2_BRIDGE_MODE_VEB		(u32)(1 << 12)
+#define IXGBE_FLAG2_PTP_PPS_ENABLED		(u32)(1 << 10)
+#define IXGBE_FLAG2_BRIDGE_MODE_VEB		(u32)(1 << 11)
 
 	/* Tx fast path data */
 	int num_tx_queues;
@@ -754,6 +753,7 @@ enum ixgbe_state_t {
 	__IXGBE_DOWN,
 	__IXGBE_SERVICE_SCHED,
 	__IXGBE_IN_SFP_INIT,
+	__IXGBE_PTP_RUNNING,
 };
 
 struct ixgbe_cb {

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -4438,7 +4438,7 @@ void ixgbe_reset(struct ixgbe_adapter *adapter)
 	if (hw->mac.san_mac_rar_index)
 		hw->mac.ops.set_vmdq_san_mac(hw, VMDQ_P(0));
 
-	if (adapter->flags2 & IXGBE_FLAG2_PTP_ENABLED)
+	if (test_bit(__IXGBE_PTP_RUNNING, &adapter->state))
 		ixgbe_ptp_reset(adapter);
 }
 
@@ -5766,7 +5766,7 @@ static void ixgbe_watchdog_link_is_up(struct ixgbe_adapter *adapter)
 
 	adapter->last_rx_ptp_check = jiffies;
 
-	if (adapter->flags2 & IXGBE_FLAG2_PTP_ENABLED)
+	if (test_bit(__IXGBE_PTP_RUNNING, &adapter->state))
 		ixgbe_ptp_start_cyclecounter(adapter);
 
 	e_info(drv, "NIC Link is Up %s, Flow Control: %s\n",
@@ -5812,7 +5812,7 @@ static void ixgbe_watchdog_link_is_down(struct ixgbe_adapter *adapter)
 	if (ixgbe_is_sfp(hw) && hw->mac.type == ixgbe_mac_82598EB)
 		adapter->flags2 |= IXGBE_FLAG2_SEARCH_FOR_SFP;
 
-	if (adapter->flags2 & IXGBE_FLAG2_PTP_ENABLED)
+	if (test_bit(__IXGBE_PTP_RUNNING, &adapter->state))
 		ixgbe_ptp_start_cyclecounter(adapter);
 
 	e_info(drv, "NIC Link is Down\n");
@@ -6119,7 +6119,7 @@ static void ixgbe_service_task(struct work_struct *work)
 	ixgbe_fdir_reinit_subtask(adapter);
 	ixgbe_check_hang_subtask(adapter);
 
-	if (adapter->flags2 & IXGBE_FLAG2_PTP_ENABLED) {
+	if (test_bit(__IXGBE_PTP_RUNNING, &adapter->state)) {
 		ixgbe_ptp_overflow_check(adapter);
 		ixgbe_ptp_rx_hang(adapter);
 	}

drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c

@@ -885,8 +885,8 @@ void ixgbe_ptp_init(struct ixgbe_adapter *adapter)
 
 	ixgbe_ptp_reset(adapter);
 
-	/* set the flag that PTP has been enabled */
-	adapter->flags2 |= IXGBE_FLAG2_PTP_ENABLED;
+	/* enter the IXGBE_PTP_RUNNING state */
+	set_bit(__IXGBE_PTP_RUNNING, &adapter->state);
 
 	return;
 }
@@ -899,10 +899,12 @@ void ixgbe_ptp_init(struct ixgbe_adapter *adapter)
  */
 void ixgbe_ptp_stop(struct ixgbe_adapter *adapter)
 {
-	/* stop the overflow check task */
-	adapter->flags2 &= ~(IXGBE_FLAG2_PTP_ENABLED |
-			     IXGBE_FLAG2_PTP_PPS_ENABLED);
+	/* Leave the IXGBE_PTP_RUNNING state. */
+	if (!test_and_clear_bit(__IXGBE_PTP_RUNNING, &adapter->state))
+		return;
 
+	/* stop the PPS signal */
+	adapter->flags2 &= ~IXGBE_FLAG2_PTP_PPS_ENABLED;
 	ixgbe_ptp_setup_sdp(adapter);
 
 	cancel_work_sync(&adapter->ptp_tx_work);