netdev - [PATCH net 4/4] iavf: validate tx_coalesce_usecs even if rx_coalesce

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Message-ID: <20231205211918.2123019-5-anthony.l.nguyen@intel.com>
Date: Tue,  5 Dec 2023 13:19:15 -0800
From: Tony Nguyen <anthony.l.nguyen@...el.com>
To: davem@...emloft.net,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com,
	netdev@...r.kernel.org
Cc: Jacob Keller <jacob.e.keller@...el.com>,
	anthony.l.nguyen@...el.com,
	Rafal Romanowski <rafal.romanowski@...el.com>
Subject: [PATCH net 4/4] iavf: validate tx_coalesce_usecs even if rx_coalesce_usecs is zero

From: Jacob Keller <jacob.e.keller@...el.com>

In __iavf_set_coalesce, the driver checks both ec->rx_coalesce_usecs and
ec->tx_coalesce_usecs for validity. It does this via a chain if if/else-if
blocks. If every single branch of the series of if statements exited, this
would be fine. However, the rx_coalesce_usecs is checked against zero to
print an informative message if use_adaptive_rx_coalesce is enabled. If
this check is true, it short circuits the entire chain of statements,
preventing validation of the tx_coalesce_usecs field.

Indeed, since commit e792779e6b63 ("iavf: Prevent changing static ITR
values if adaptive moderation is on") the iavf driver actually rejects any
change to the tx_coalesce_usecs or rx_coalesce_usecs when
use_adaptive_tx_coalesce or use_adaptive_rx_coalesce is enabled, making
this checking a bit redundant.

Fix this error by removing the unnecessary and redundant checks for
use_adaptive_rx_coalesce and use_adaptive_tx_coalesce. Since zero is a
valid value, and since the tx_coalesce_usecs and rx_coalesce_usecs fields
are already unsigned, remove the minimum value check. This allows assigning
an ITR value ranging from 0-8160 as described by the printed message.

Fixes: 65e87c0398f5 ("i40evf: support queue-specific settings for interrupt moderation")
Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
Tested-by: Rafal Romanowski <rafal.romanowski@...el.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/iavf/iavf_ethtool.c | 12 ++----------
 drivers/net/ethernet/intel/iavf/iavf_txrx.h    |  1 -
 2 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
index 6f236d1a6444..19cbfe554689 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
@@ -827,18 +827,10 @@ static int __iavf_set_coalesce(struct net_device *netdev,
 	struct iavf_adapter *adapter = netdev_priv(netdev);
 	int i;
 
-	if (ec->rx_coalesce_usecs == 0) {
-		if (ec->use_adaptive_rx_coalesce)
-			netif_info(adapter, drv, netdev, "rx-usecs=0, need to disable adaptive-rx for a complete disable\n");
-	} else if ((ec->rx_coalesce_usecs < IAVF_MIN_ITR) ||
-		   (ec->rx_coalesce_usecs > IAVF_MAX_ITR)) {
+	if (ec->rx_coalesce_usecs > IAVF_MAX_ITR) {
 		netif_info(adapter, drv, netdev, "Invalid value, rx-usecs range is 0-8160\n");
 		return -EINVAL;
-	} else if (ec->tx_coalesce_usecs == 0) {
-		if (ec->use_adaptive_tx_coalesce)
-			netif_info(adapter, drv, netdev, "tx-usecs=0, need to disable adaptive-tx for a complete disable\n");
-	} else if ((ec->tx_coalesce_usecs < IAVF_MIN_ITR) ||
-		   (ec->tx_coalesce_usecs > IAVF_MAX_ITR)) {
+	} else if (ec->tx_coalesce_usecs > IAVF_MAX_ITR) {
 		netif_info(adapter, drv, netdev, "Invalid value, tx-usecs range is 0-8160\n");
 		return -EINVAL;
 	}
diff --git a/drivers/net/ethernet/intel/iavf/iavf_txrx.h b/drivers/net/ethernet/intel/iavf/iavf_txrx.h
index 7e6ee32d19b6..10ba36602c0c 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_txrx.h
+++ b/drivers/net/ethernet/intel/iavf/iavf_txrx.h
@@ -15,7 +15,6 @@
  */
 #define IAVF_ITR_DYNAMIC	0x8000	/* use top bit as a flag */
 #define IAVF_ITR_MASK		0x1FFE	/* mask for ITR register value */
-#define IAVF_MIN_ITR		     2	/* reg uses 2 usec resolution */
 #define IAVF_ITR_100K		    10	/* all values below must be even */
 #define IAVF_ITR_50K		    20
 #define IAVF_ITR_20K		    50
-- 
2.41.0