[PATCH iwl-next v3 4/9] ice: move prev_pkt from ice_txq_stats to ice_tx_ring

[Jacob Keller <jacob.e.keller@intel.com>]

The prev_pkt field in ice_txq_stats is used by ice_check_for_hung_subtask
as a way to detect potential Tx hangs due to missed interrupts.

The value is based on the packet count, but its an int and not really a
"statistic". The value is signed so that we can use -1 as a "no work
pending" value. A following change is going to refactor the stats to all
use the u64_stat_t type and accessor functions. Leaving prev_pkt as the
lone int feels a bit strange.

Instead, move it out of ice_txq_stats and place it in the ice_tx_ring. We
have 8 bytes still available in the 3rd cacheline, so this move saves a
small amount of memory. It also shouldn't impact the Tx path heavily since
its only accessed during initialization and the hang subtask.

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_txrx.h | 3 ++-
 drivers/net/ethernet/intel/ice/ice_main.c | 6 +++---
 drivers/net/ethernet/intel/ice/ice_txrx.c | 2 +-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.h b/drivers/net/ethernet/intel/ice/ice_txrx.h
index 78fed538ea0f..aa0b74e45bba 100644
--- a/drivers/net/ethernet/intel/ice/ice_txrx.h
+++ b/drivers/net/ethernet/intel/ice/ice_txrx.h
@@ -138,7 +138,6 @@ struct ice_txq_stats {
 	u64 restart_q;
 	u64 tx_busy;
 	u64 tx_linearize;
-	int prev_pkt; /* negative if no pending Tx descriptors */
 };
 
 struct ice_rxq_stats {
@@ -354,6 +353,8 @@ struct ice_tx_ring {
 
 	u32 txq_teid;			/* Added Tx queue TEID */
 
+	int prev_pkt; /* negative if no pending Tx descriptors */
+
 #define ICE_TX_FLAGS_RING_XDP		BIT(0)
 #define ICE_TX_FLAGS_RING_VLAN_L2TAG1	BIT(1)
 #define ICE_TX_FLAGS_RING_VLAN_L2TAG2	BIT(2)
diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index 645a2113e8aa..df5da7b4ec62 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -160,7 +160,7 @@ static void ice_check_for_hang_subtask(struct ice_pf *pf)
 			 * pending work.
 			 */
 			packets = ring_stats->stats.pkts & INT_MAX;
-			if (ring_stats->tx_stats.prev_pkt == packets) {
+			if (tx_ring->prev_pkt == packets) {
 				/* Trigger sw interrupt to revive the queue */
 				ice_trigger_sw_intr(hw, tx_ring->q_vector);
 				continue;
@@ -170,8 +170,8 @@ static void ice_check_for_hang_subtask(struct ice_pf *pf)
 			 * to ice_get_tx_pending()
 			 */
 			smp_rmb();
-			ring_stats->tx_stats.prev_pkt =
-			    ice_get_tx_pending(tx_ring) ? packets : -1;
+			tx_ring->prev_pkt =
+				ice_get_tx_pending(tx_ring) ? packets : -1;
 		}
 	}
 }
diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c
index ad76768a4232..30073ed9ca99 100644
--- a/drivers/net/ethernet/intel/ice/ice_txrx.c
+++ b/drivers/net/ethernet/intel/ice/ice_txrx.c
@@ -499,7 +499,7 @@ int ice_setup_tx_ring(struct ice_tx_ring *tx_ring)
 
 	tx_ring->next_to_use = 0;
 	tx_ring->next_to_clean = 0;
-	tx_ring->ring_stats->tx_stats.prev_pkt = -1;
+	tx_ring->prev_pkt = -1;
 	return 0;
 
 err:

-- 
2.51.0.rc1.197.g6d975e95c9d7