netdev - [PATCH net-next 10/10] i40e: fix race conditions on queuing skb for HW time stamp

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Date:	Fri, 14 Mar 2014 18:34:41 +0100
From:	Jakub Kicinski <kubakici@...pl>
To:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:	Jakub Kicinski <kubakici@...pl>, netdev@...r.kernel.org,
	e1000-devel@...ts.sourceforge.net
Subject: [PATCH net-next 10/10] i40e: fix race conditions on queuing skb for HW time stamp

i40e has a single set of TX time stamping resources per NIC.
Use a simple bit lock to avoid race conditions and leaking skbs
when multiple TX rings try to claim time stamping.

Signed-off-by: Jakub Kicinski <kubakici@...pl>
---
 drivers/net/ethernet/intel/i40e/i40e.h      | 1 +
 drivers/net/ethernet/intel/i40e/i40e_ptp.c  | 3 +++
 drivers/net/ethernet/intel/i40e/i40e_txrx.c | 3 ++-
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index 838b69b..7ed0303 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -136,6 +136,7 @@ enum i40e_state_t {
 	__I40E_EMP_RESET_REQUESTED,
 	__I40E_FILTER_OVERFLOW_PROMISC,
 	__I40E_SUSPENDED,
+	__I40E_PTP_TX_IN_PROGRESS,
 };
 
 enum i40e_interrupt_policy {
diff --git a/drivers/net/ethernet/intel/i40e/i40e_ptp.c b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
index e33ec6c..545079c 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_ptp.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
@@ -238,6 +238,7 @@ static void i40e_ptp_tx_work(struct work_struct *work)
 				   I40E_PTP_TX_TIMEOUT)) {
 		dev_kfree_skb_any(pf->ptp_tx_skb);
 		pf->ptp_tx_skb = NULL;
+		clear_bit_unlock(__I40E_PTP_TX_IN_PROGRESS, &pf->state);
 		pf->tx_hwtstamp_timeouts++;
 		dev_warn(&pf->pdev->dev, "clearing Tx timestamp hang");
 		return;
@@ -350,6 +351,7 @@ void i40e_ptp_tx_hwtstamp(struct i40e_pf *pf)
 	skb_tstamp_tx(pf->ptp_tx_skb, &shhwtstamps);
 	dev_kfree_skb_any(pf->ptp_tx_skb);
 	pf->ptp_tx_skb = NULL;
+	clear_bit_unlock(__I40E_PTP_TX_IN_PROGRESS, &pf->state);
 }
 
 /**
@@ -651,6 +653,7 @@ void i40e_ptp_stop(struct i40e_pf *pf)
 	if (pf->ptp_tx_skb) {
 		dev_kfree_skb_any(pf->ptp_tx_skb);
 		pf->ptp_tx_skb = NULL;
+		clear_bit_unlock(__I40E_PTP_TX_IN_PROGRESS, &pf->state);
 	}
 
 	if (pf->ptp_clock) {
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 9543683..9db6efa 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -1746,7 +1746,8 @@ static int i40e_tsyn(struct i40e_ring *tx_ring, struct sk_buff *skb,
 	 * we are not already transmitting a packet to be timestamped
 	 */
 	pf = i40e_netdev_to_pf(tx_ring->netdev);
-	if (pf->ptp_tx && !pf->ptp_tx_skb) {
+	if (pf->ptp_tx &&
+	    !test_and_set_bit_lock(__I40E_PTP_TX_IN_PROGRESS, &pf->state)) {
 		skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
 		pf->ptp_tx_skb = skb_get(skb);
 	} else {
-- 
1.8.5.3

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