[PATCH net-next] enic: add sw timestamp support

[PATCH net-next] enic: add sw timestamp support

[Govindarajulu Varadarajan]

Add ethtool ops to advertise sw timestamping.
Call skb_tx_timestamp() just before ringing the wq doorbell.

Signed-off-by: Govindarajulu Varadarajan <gvaradar@cisco.com>
---
 drivers/net/ethernet/cisco/enic/enic_ethtool.c | 12 ++++++++++++
 drivers/net/ethernet/cisco/enic/enic_main.c    |  1 +
 2 files changed, 13 insertions(+)

diff --git a/drivers/net/ethernet/cisco/enic/enic_ethtool.c b/drivers/net/ethernet/cisco/enic/enic_ethtool.c
index 462d0ce51240..efb9333c7cf8 100644
--- a/drivers/net/ethernet/cisco/enic/enic_ethtool.c
+++ b/drivers/net/ethernet/cisco/enic/enic_ethtool.c
@@ -18,6 +18,7 @@
 
 #include <linux/netdevice.h>
 #include <linux/ethtool.h>
+#include <linux/net_tstamp.h>
 
 #include "enic_res.h"
 #include "enic.h"
@@ -578,6 +579,16 @@ static int enic_set_rxfh(struct net_device *netdev, const u32 *indir,
 	return __enic_set_rsskey(enic);
 }
 
+static int enic_get_ts_info(struct net_device *netdev,
+			    struct ethtool_ts_info *info)
+{
+	info->so_timestamping = SOF_TIMESTAMPING_TX_SOFTWARE |
+				SOF_TIMESTAMPING_RX_SOFTWARE |
+				SOF_TIMESTAMPING_SOFTWARE;
+
+	return 0;
+}
+
 static const struct ethtool_ops enic_ethtool_ops = {
 	.get_drvinfo = enic_get_drvinfo,
 	.get_msglevel = enic_get_msglevel,
@@ -597,6 +608,7 @@ static const struct ethtool_ops enic_ethtool_ops = {
 	.get_rxfh = enic_get_rxfh,
 	.set_rxfh = enic_set_rxfh,
 	.get_link_ksettings = enic_get_ksettings,
+	.get_ts_info = enic_get_ts_info,
 };
 
 void enic_set_ethtool_ops(struct net_device *netdev)
diff --git a/drivers/net/ethernet/cisco/enic/enic_main.c b/drivers/net/ethernet/cisco/enic/enic_main.c
index e130fb757e7b..d98676e43e03 100644
--- a/drivers/net/ethernet/cisco/enic/enic_main.c
+++ b/drivers/net/ethernet/cisco/enic/enic_main.c
@@ -856,6 +856,7 @@ static netdev_tx_t enic_hard_start_xmit(struct sk_buff *skb,
 
 	if (vnic_wq_desc_avail(wq) < MAX_SKB_FRAGS + ENIC_DESC_MAX_SPLITS)
 		netif_tx_stop_queue(txq);
+	skb_tx_timestamp(skb);
 	if (!skb->xmit_more || netif_xmit_stopped(txq))
 		vnic_wq_doorbell(wq);
 
-- 
2.15.0

Re: [PATCH net-next] enic: add sw timestamp support

[David Miller]

From: Govindarajulu Varadarajan <gvaradar@cisco.com>
Date: Fri,  1 Dec 2017 10:21:40 -0800

> Add ethtool ops to advertise sw timestamping.
> Call skb_tx_timestamp() just before ringing the wq doorbell.
> 
> Signed-off-by: Govindarajulu Varadarajan <gvaradar@cisco.com>
...
> diff --git a/drivers/net/ethernet/cisco/enic/enic_main.c b/drivers/net/ethernet/cisco/enic/enic_main.c
> index e130fb757e7b..d98676e43e03 100644
> --- a/drivers/net/ethernet/cisco/enic/enic_main.c
> +++ b/drivers/net/ethernet/cisco/enic/enic_main.c
> @@ -856,6 +856,7 @@ static netdev_tx_t enic_hard_start_xmit(struct sk_buff *skb,
>  
>  	if (vnic_wq_desc_avail(wq) < MAX_SKB_FRAGS + ENIC_DESC_MAX_SPLITS)
>  		netif_tx_stop_queue(txq);
> +	skb_tx_timestamp(skb);
>  	if (!skb->xmit_more || netif_xmit_stopped(txq))
>  		vnic_wq_doorbell(wq);
>  

Applied, but if you even make this queue processing code lockless you will
have a use-after-free here as you're placing the SKB into the TX queue
before accessing the 'skb' via skb_tx_timestamp() and it thus could be
freed by TX completion beforehand.