netdev - [PATCH net 2/4] igc: Check if hardware TX timestamping is enabled earlier

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Date: Tue, 30 May 2023 10:49:26 -0700
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: Vinicius Costa Gomes <vinicius.gomes@...el.com>,
	anthony.l.nguyen@...el.com,
	sasha.neftin@...el.com,
	richardcochran@...il.com,
	Vladimir Oltean <vladimir.oltean@....com>,
	Naama Meir <naamax.meir@...ux.intel.com>
Subject: [PATCH net 2/4] igc: Check if hardware TX timestamping is enabled earlier

From: Vinicius Costa Gomes <vinicius.gomes@...el.com>

Before requesting a packet transmission to be hardware timestamped,
check if the user has TX timestamping enabled. Fixes an issue that if
a packet was internally forwarded to the NIC, and it had the
SKBTX_HW_TSTAMP flag set, the driver would mark that timestamp as
skipped.

In reality, that timestamp was "not for us", as TX timestamp could
never be enabled in the NIC.

Checking if the TX timestamping is enabled earlier has a secondary
effect that when TX timestamping is disabled, there's no need to check
for timestamp timeouts.

We should only take care to free any pending timestamp when TX
timestamping is disabled, as that skb would never be released
otherwise.

Fixes: 2c344ae24501 ("igc: Add support for TX timestamping")
Suggested-by: Vladimir Oltean <vladimir.oltean@....com>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
Tested-by: Naama Meir <naamax.meir@...ux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c |  5 +++--
 drivers/net/ethernet/intel/igc/igc_ptp.c  | 23 ++++++++++++++++++++---
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index a61afa69975e..b383352651a5 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -1578,7 +1578,8 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
 		}
 	}
 
-	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
+	if (unlikely(adapter->tstamp_config.tx_type == HWTSTAMP_TX_ON &&
+		     skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
 		/* FIXME: add support for retrieving timestamps from
 		 * the other timer registers before skipping the
 		 * timestamping request.
@@ -1586,7 +1587,7 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
 		unsigned long flags;
 
 		spin_lock_irqsave(&adapter->ptp_tx_lock, flags);
-		if (adapter->tstamp_config.tx_type == HWTSTAMP_TX_ON && !adapter->ptp_tx_skb) {
+		if (!adapter->ptp_tx_skb) {
 			skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
 			tx_flags |= IGC_TX_FLAGS_TSTAMP;
 
diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
index 56128e55f5c0..4dd0eec5a246 100644
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -536,11 +536,27 @@ static void igc_ptp_enable_rx_timestamp(struct igc_adapter *adapter)
 	wr32(IGC_TSYNCRXCTL, val);
 }
 
+static void igc_ptp_clear_tx_tstamp(struct igc_adapter *adapter)
+{
+	unsigned long flags;
+
+	cancel_work_sync(&adapter->ptp_tx_work);
+
+	spin_lock_irqsave(&adapter->ptp_tx_lock, flags);
+
+	dev_kfree_skb_any(adapter->ptp_tx_skb);
+	adapter->ptp_tx_skb = NULL;
+
+	spin_unlock_irqrestore(&adapter->ptp_tx_lock, flags);
+}
+
 static void igc_ptp_disable_tx_timestamp(struct igc_adapter *adapter)
 {
 	struct igc_hw *hw = &adapter->hw;
 
 	wr32(IGC_TSYNCTXCTL, 0);
+
+	igc_ptp_clear_tx_tstamp(adapter);
 }
 
 static void igc_ptp_enable_tx_timestamp(struct igc_adapter *adapter)
@@ -620,6 +636,9 @@ void igc_ptp_tx_hang(struct igc_adapter *adapter)
 {
 	unsigned long flags;
 
+	if (adapter->tstamp_config.tx_type != HWTSTAMP_TX_ON)
+		return;
+
 	spin_lock_irqsave(&adapter->ptp_tx_lock, flags);
 
 	if (!adapter->ptp_tx_skb)
@@ -1026,9 +1045,7 @@ void igc_ptp_suspend(struct igc_adapter *adapter)
 	if (!(adapter->ptp_flags & IGC_PTP_ENABLED))
 		return;
 
-	cancel_work_sync(&adapter->ptp_tx_work);
-	dev_kfree_skb_any(adapter->ptp_tx_skb);
-	adapter->ptp_tx_skb = NULL;
+	igc_ptp_clear_tx_tstamp(adapter);
 
 	if (pci_device_is_present(adapter->pdev)) {
 		igc_ptp_time_save(adapter);
-- 
2.38.1