[PATCH 6.4 200/800] igc: Check if hardware TX timestamping is enabled earlier

Greg Kroah-Hartman
2023-07-16T20:02:11Z

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

[ Upstream commit ce58c7cc8b9910f2bc1d038d7ba60c3f011b2cb2 ]

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@nxp.com>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/intel/igc/igc.h | 1 +
drivers/net/ethernet/intel/igc/igc_main.c | 5 +--
drivers/net/ethernet/intel/igc/igc_ptp.c | 42 +++++++++++++++++++++--
3 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index ef4d284634047..70de8b9bbe591 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -609,6 +609,7 @@ enum igc_ring_flags_t {
IGC_RING_FLAG_TX_CTX_IDX,
IGC_RING_FLAG_TX_DETECT_HANG,
IGC_RING_FLAG_AF_XDP_ZC,
+ IGC_RING_FLAG_TX_HWTSTAMP,
};

#define ring_uses_large_buffer(ring) \
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index fb4b543665f71..d0c067da7aac8 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -1585,7 +1585,8 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
}
}

- if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
+ if (unlikely(test_bit(IGC_RING_FLAG_TX_HWTSTAMP, &tx_ring->flags) &&
+ skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
/* FIXME: add support for retrieving timestamps from
* the other timer registers before skipping the
* timestamping request.
@@ -1593,7 +1594,7 @@ 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 56128e55f5c03..42f622ceb64bb 100644
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -536,9 +536,36 @@ 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;
+ int i;
+
+ /* Clear the flags first to avoid new packets to be enqueued
+ * for TX timestamping.
+ */
+ for (i = 0; i < adapter->num_tx_queues; i++) {
+ struct igc_ring *tx_ring = adapter->tx_ring[i];
+
+ clear_bit(IGC_RING_FLAG_TX_HWTSTAMP, &tx_ring->flags);
+ }
+
+ /* Now we can clean the pending TX timestamp requests. */
+ igc_ptp_clear_tx_tstamp(adapter);

wr32(IGC_TSYNCTXCTL, 0);
}
@@ -546,12 +573,23 @@ static void igc_ptp_disable_tx_timestamp(struct igc_adapter *adapter)
static void igc_ptp_enable_tx_timestamp(struct igc_adapter *adapter)
{
struct igc_hw *hw = &adapter->hw;
+ int i;

wr32(IGC_TSYNCTXCTL, IGC_TSYNCTXCTL_ENABLED | IGC_TSYNCTXCTL_TXSYNSIG);

/* Read TXSTMP registers to discard any timestamp previously stored. */
rd32(IGC_TXSTMPL);
rd32(IGC_TXSTMPH);
+
+ /* The hardware is ready to accept TX timestamp requests,
+ * notify the transmit path.
+ */
+ for (i = 0; i < adapter->num_tx_queues; i++) {
+ struct igc_ring *tx_ring = adapter->tx_ring[i];
+
+ set_bit(IGC_RING_FLAG_TX_HWTSTAMP, &tx_ring->flags);
+ }
+
}

/**
@@ -1026,9 +1064,7 @@ 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);
--
2.39.2