[PATCH V1 net 1/2] net: ena: fix issues in setting interrupt moderation params in ethtool

[<akiyano@amazon.com>]

From: Arthur Kiyanovski <akiyano@amazon.com>

Issue 1:
--------
Reproduction steps:
1. sudo ethtool -C eth0 rx-usecs 128
2. sudo ethtool -C eth0 adaptive-rx on
3. sudo ethtool -C eth0 adaptive-rx off
4. ethtool -c eth0

expected output: rx-usecs 128
actual output: rx-usecs 0

Reason for issue:
In stage 3, ethtool userspace calls first the ena_get_coalesce() handler
to get the current value of all properties, and then the ena_set_coalesce()
handler. When ena_get_coalesce() is called the adaptive interrupt
moderation is still on. There is an if in the code that returns the
rx_coalesce_usecs only if the adaptive interrupt moderation is off.
And since it is still on, rx_coalesce_usecs is not set, meaning it
stays 0.

Solution to issue:
Remove this if static interrupt moderation intervals have nothing to do with
dynamic ones.

Issue 2:
--------
Reproduction steps:
1. sudo ethtool -C eth0 rx-usecs 128
2. sudo ethtool -C eth0 adaptive-rx on
3. sudo ethtool -C eth0 rx-usecs 128
4. ethtool -c eth0

expected output: rx-usecs 128
actual output: rx-usecs 0

Reason for issue:
In stage 3, when ena_set_coalesce() is called, the handler tests if
rx adaptive interrupt moderation is on, and if it is, it returns before
getting to the part in the function that sets the rx non-adaptive
interrupt moderation interval.

Solution to issue:
Remove the return from the function when rx adaptive interrupt moderation
is on.

Additional small fixes in this commit:
--------------------------------------
1. Remove 2 unnecessary comments.
2. Remove 4 unnecesary "{}" in single row if statements.
3. Reorder ena_set_coalesce() to make sense.
4. Change the names of ena_update_tx/rx_rings_intr_moderation()
   functions to ena_update_tx/rx_rings_nonadaptive_intr_moderation() for
   clarity.

Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
---
 drivers/net/ethernet/amazon/ena/ena_ethtool.c | 40 ++++++++-----------
 1 file changed, 16 insertions(+), 24 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_ethtool.c b/drivers/net/ethernet/amazon/ena/ena_ethtool.c
index 16553d92fad2..b042c70504cd 100644
--- a/drivers/net/ethernet/amazon/ena/ena_ethtool.c
+++ b/drivers/net/ethernet/amazon/ena/ena_ethtool.c
@@ -306,19 +306,16 @@ static int ena_get_coalesce(struct net_device *net_dev,
 	struct ena_adapter *adapter = netdev_priv(net_dev);
 	struct ena_com_dev *ena_dev = adapter->ena_dev;
 
-	if (!ena_com_interrupt_moderation_supported(ena_dev)) {
-		/* the devie doesn't support interrupt moderation */
+	if (!ena_com_interrupt_moderation_supported(ena_dev))
 		return -EOPNOTSUPP;
-	}
 
 	coalesce->tx_coalesce_usecs =
 		ena_com_get_nonadaptive_moderation_interval_tx(ena_dev) *
 			ena_dev->intr_delay_resolution;
 
-	if (!ena_com_get_adaptive_moderation_enabled(ena_dev))
-		coalesce->rx_coalesce_usecs =
-			ena_com_get_nonadaptive_moderation_interval_rx(ena_dev)
-			* ena_dev->intr_delay_resolution;
+	coalesce->rx_coalesce_usecs =
+		ena_com_get_nonadaptive_moderation_interval_rx(ena_dev)
+		* ena_dev->intr_delay_resolution;
 
 	coalesce->use_adaptive_rx_coalesce =
 		ena_com_get_adaptive_moderation_enabled(ena_dev);
@@ -326,7 +323,7 @@ static int ena_get_coalesce(struct net_device *net_dev,
 	return 0;
 }
 
-static void ena_update_tx_rings_intr_moderation(struct ena_adapter *adapter)
+static void ena_update_tx_rings_nonadaptive_intr_moderation(struct ena_adapter *adapter)
 {
 	unsigned int val;
 	int i;
@@ -337,7 +334,7 @@ static void ena_update_tx_rings_intr_moderation(struct ena_adapter *adapter)
 		adapter->tx_ring[i].smoothed_interval = val;
 }
 
-static void ena_update_rx_rings_intr_moderation(struct ena_adapter *adapter)
+static void ena_update_rx_rings_nonadaptive_intr_moderation(struct ena_adapter *adapter)
 {
 	unsigned int val;
 	int i;
@@ -355,35 +352,30 @@ static int ena_set_coalesce(struct net_device *net_dev,
 	struct ena_com_dev *ena_dev = adapter->ena_dev;
 	int rc;
 
-	if (!ena_com_interrupt_moderation_supported(ena_dev)) {
-		/* the devie doesn't support interrupt moderation */
+	if (!ena_com_interrupt_moderation_supported(ena_dev))
 		return -EOPNOTSUPP;
-	}
 
 	rc = ena_com_update_nonadaptive_moderation_interval_tx(ena_dev,
 							       coalesce->tx_coalesce_usecs);
 	if (rc)
 		return rc;
 
-	ena_update_tx_rings_intr_moderation(adapter);
-
-	if (coalesce->use_adaptive_rx_coalesce) {
-		if (!ena_com_get_adaptive_moderation_enabled(ena_dev))
-			ena_com_enable_adaptive_moderation(ena_dev);
-		return 0;
-	}
+	ena_update_tx_rings_nonadaptive_intr_moderation(adapter);
 
 	rc = ena_com_update_nonadaptive_moderation_interval_rx(ena_dev,
 							       coalesce->rx_coalesce_usecs);
 	if (rc)
 		return rc;
 
-	ena_update_rx_rings_intr_moderation(adapter);
+	ena_update_rx_rings_nonadaptive_intr_moderation(adapter);
 
-	if (!coalesce->use_adaptive_rx_coalesce) {
-		if (ena_com_get_adaptive_moderation_enabled(ena_dev))
-			ena_com_disable_adaptive_moderation(ena_dev);
-	}
+	if ((coalesce->use_adaptive_rx_coalesce) &&
+	    (!ena_com_get_adaptive_moderation_enabled(ena_dev)))
+		ena_com_enable_adaptive_moderation(ena_dev);
+
+	if ((!coalesce->use_adaptive_rx_coalesce) &&
+	    (ena_com_get_adaptive_moderation_enabled(ena_dev)))
+		ena_com_disable_adaptive_moderation(ena_dev);
 
 	return 0;
 }
-- 
2.17.1