netdev - [PATCH V2 net 2/2] net: ena: fix issues in setting interrupt moderation params in ethtool

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Date:   Thu, 19 Dec 2019 17:40:56 +0200
From:   <akiyano@...zon.com>
To:     <davem@...emloft.net>, <netdev@...r.kernel.org>
CC:     Arthur Kiyanovski <akiyano@...zon.com>, <dwmw@...zon.com>,
        <zorik@...zon.com>, <matua@...zon.com>, <saeedb@...zon.com>,
        <msw@...zon.com>, <aliguori@...zon.com>, <nafea@...zon.com>,
        <gtzalik@...zon.com>, <netanel@...zon.com>, <alisaidi@...zon.com>,
        <benh@...zon.com>, <ndagan@...zon.com>, <shayagr@...zon.com>,
        <sameehj@...zon.com>
Subject: [PATCH V2 net 2/2] net: ena: fix issues in setting interrupt moderation params in ethtool

From: Arthur Kiyanovski <akiyano@...zon.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 adaptive-rx on
2. sudo ethtool -C eth0 rx-usecs 128
3. ethtool -c eth0

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

Reason for issue:
In stage 2, 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.

Also cleaned up the fixed code in ena_set_coalesce by grouping together
adaptive interrupt moderation toggling, and using && instead of nested
ifs.

Fixes: b3db86dc4b82 ("net: ena: reimplement set/get_coalesce()")
Fixes: 0eda847953d8 ("net: ena: fix retrieval of nonadaptive interrupt moderation intervals")
Fixes: 1738cd3ed342 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")

Signed-off-by: Arthur Kiyanovski <akiyano@...zon.com>
---
 drivers/net/ethernet/amazon/ena/ena_ethtool.c | 24 ++++++++++--------------
 1 file changed, 10 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_ethtool.c b/drivers/net/ethernet/amazon/ena/ena_ethtool.c
index a3250dc..fc96c66 100644
--- a/drivers/net/ethernet/amazon/ena/ena_ethtool.c
+++ b/drivers/net/ethernet/amazon/ena/ena_ethtool.c
@@ -315,10 +315,9 @@ static int ena_get_coalesce(struct net_device *net_dev,
 		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);
@@ -367,12 +366,6 @@ static int ena_set_coalesce(struct net_device *net_dev,
 
 	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;
-	}
-
 	rc = ena_com_update_nonadaptive_moderation_interval_rx(ena_dev,
 							       coalesce->rx_coalesce_usecs);
 	if (rc)
@@ -380,10 +373,13 @@ static int ena_set_coalesce(struct net_device *net_dev,
 
 	ena_update_rx_rings_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;
 }
-- 
2.7.4