[PATCH 2/3] net: openvswitch: use core API for updating TX stats

[PATCH 2/3] net: openvswitch: use core API for updating TX stats

[Lev Stipakov]

Commit d3fd65484c781 ("net: core: add dev_sw_netstats_tx_add") has added
function "dev_sw_netstats_tx_add()" to update net device per-cpu TX
stats.

Use this function instead of own code. While on it, replace
"len" variable with "skb->len".

Signed-off-by: Lev Stipakov <lev@openvpn.net>
---
 net/openvswitch/vport-internal_dev.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/net/openvswitch/vport-internal_dev.c b/net/openvswitch/vport-internal_dev.c
index 1e30d8df3ba5..116738d36e02 100644
--- a/net/openvswitch/vport-internal_dev.c
+++ b/net/openvswitch/vport-internal_dev.c
@@ -33,23 +33,17 @@ static struct internal_dev *internal_dev_priv(struct net_device *netdev)
 static netdev_tx_t
 internal_dev_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
-	int len, err;
+	int err;
 
-	len = skb->len;
 	rcu_read_lock();
 	err = ovs_vport_receive(internal_dev_priv(netdev)->vport, skb, NULL);
 	rcu_read_unlock();
 
-	if (likely(!err)) {
-		struct pcpu_sw_netstats *tstats = this_cpu_ptr(netdev->tstats);
-
-		u64_stats_update_begin(&tstats->syncp);
-		tstats->tx_bytes += len;
-		tstats->tx_packets++;
-		u64_stats_update_end(&tstats->syncp);
-	} else {
+	if (likely(!err))
+		dev_sw_netstats_tx_add(netdev, 1, skb->len);
+	else
 		netdev->stats.tx_errors++;
-	}
+
 	return NETDEV_TX_OK;
 }
 
-- 
2.25.1

Re: [PATCH 2/3] net: openvswitch: use core API for updating TX stats

[Heiner Kallweit]

Am 12.11.2020 um 12:11 schrieb Lev Stipakov:
> Commit d3fd65484c781 ("net: core: add dev_sw_netstats_tx_add") has added
> function "dev_sw_netstats_tx_add()" to update net device per-cpu TX
> stats.
> 
> Use this function instead of own code. While on it, replace
> "len" variable with "skb->len".
> 
Using dev_sw_netstats_tx_add() is fine, however you have to keep
variable len, see remark in the code.

In addition you can replace internal_get_stats() with dev_get_tstats64().

> Signed-off-by: Lev Stipakov <lev@openvpn.net>
> ---
>  net/openvswitch/vport-internal_dev.c | 16 +++++-----------
>  1 file changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/net/openvswitch/vport-internal_dev.c b/net/openvswitch/vport-internal_dev.c
> index 1e30d8df3ba5..116738d36e02 100644
> --- a/net/openvswitch/vport-internal_dev.c
> +++ b/net/openvswitch/vport-internal_dev.c
> @@ -33,23 +33,17 @@ static struct internal_dev *internal_dev_priv(struct net_device *netdev)
>  static netdev_tx_t
>  internal_dev_xmit(struct sk_buff *skb, struct net_device *netdev)
>  {
> -	int len, err;
> +	int err;
>  
> -	len = skb->len;
>  	rcu_read_lock();
>  	err = ovs_vport_receive(internal_dev_priv(netdev)->vport, skb, NULL);

We would have a well-hidden problem here. ovs_vport_receive() calls function
ovs_dp_process_packet() that frees the skb under certain circumstances.
Note that the skb can be freed even if ovs_vport_receive() returns OK.
Using skb->len after calling ovs_vport_receive() could result in a
use-after-free therefore. So you have to keep variable len.

>  	rcu_read_unlock();
>  
> -	if (likely(!err)) {
> -		struct pcpu_sw_netstats *tstats = this_cpu_ptr(netdev->tstats);
> -
> -		u64_stats_update_begin(&tstats->syncp);
> -		tstats->tx_bytes += len;
> -		tstats->tx_packets++;
> -		u64_stats_update_end(&tstats->syncp);
> -	} else {
> +	if (likely(!err))
> +		dev_sw_netstats_tx_add(netdev, 1, skb->len);
> +	else
>  		netdev->stats.tx_errors++;
> -	}
> +
>  	return NETDEV_TX_OK;
>  }
>  
> 

[PATCH v2 2/3] net: openvswitch: use core API to update/provide stats

[Lev Stipakov]

Commit d3fd65484c781 ("net: core: add dev_sw_netstats_tx_add") has added
function "dev_sw_netstats_tx_add()" to update net device per-cpu TX
stats.

Use this function instead of own code.

While on it, remove internal_get_stats() and replace it
with dev_get_tstats64().

Signed-off-by: Lev Stipakov <lev@openvpn.net>
---

 v2:
  - do not delete len variable and add comment why
  - replace internal_get_stats() vs dev_get_tstats64()

 net/openvswitch/vport-internal_dev.c | 29 +++++++---------------------
 1 file changed, 7 insertions(+), 22 deletions(-)

diff --git a/net/openvswitch/vport-internal_dev.c b/net/openvswitch/vport-internal_dev.c
index 1e30d8df3ba5..5b2ee9c1c00b 100644
--- a/net/openvswitch/vport-internal_dev.c
+++ b/net/openvswitch/vport-internal_dev.c
@@ -35,21 +35,18 @@ internal_dev_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	int len, err;
 
+	/* store len value because skb can be freed inside ovs_vport_receive() */
 	len = skb->len;
+
 	rcu_read_lock();
 	err = ovs_vport_receive(internal_dev_priv(netdev)->vport, skb, NULL);
 	rcu_read_unlock();
 
-	if (likely(!err)) {
-		struct pcpu_sw_netstats *tstats = this_cpu_ptr(netdev->tstats);
-
-		u64_stats_update_begin(&tstats->syncp);
-		tstats->tx_bytes += len;
-		tstats->tx_packets++;
-		u64_stats_update_end(&tstats->syncp);
-	} else {
+	if (likely(!err))
+		dev_sw_netstats_tx_add(netdev, 1, len);
+	else
 		netdev->stats.tx_errors++;
-	}
+
 	return NETDEV_TX_OK;
 }
 
@@ -83,24 +80,12 @@ static void internal_dev_destructor(struct net_device *dev)
 	ovs_vport_free(vport);
 }
 
-static void
-internal_get_stats(struct net_device *dev, struct rtnl_link_stats64 *stats)
-{
-	memset(stats, 0, sizeof(*stats));
-	stats->rx_errors  = dev->stats.rx_errors;
-	stats->tx_errors  = dev->stats.tx_errors;
-	stats->tx_dropped = dev->stats.tx_dropped;
-	stats->rx_dropped = dev->stats.rx_dropped;
-
-	dev_fetch_sw_netstats(stats, dev->tstats);
-}
-
 static const struct net_device_ops internal_dev_netdev_ops = {
 	.ndo_open = internal_dev_open,
 	.ndo_stop = internal_dev_stop,
 	.ndo_start_xmit = internal_dev_xmit,
 	.ndo_set_mac_address = eth_mac_addr,
-	.ndo_get_stats64 = internal_get_stats,
+	.ndo_get_stats64 = dev_get_tstats64,
 };
 
 static struct rtnl_link_ops internal_dev_link_ops __read_mostly = {
-- 
2.25.1

Re: [PATCH v2 2/3] net: openvswitch: use core API to update/provide stats

[Heiner Kallweit]

Am 13.11.2020 um 10:02 schrieb Lev Stipakov:
> Commit d3fd65484c781 ("net: core: add dev_sw_netstats_tx_add") has added
> function "dev_sw_netstats_tx_add()" to update net device per-cpu TX
> stats.
> 
> Use this function instead of own code.
> 
> While on it, remove internal_get_stats() and replace it
> with dev_get_tstats64().
> 
> Signed-off-by: Lev Stipakov <lev@openvpn.net>
> ---
> 
>  v2:
>   - do not delete len variable and add comment why
>   - replace internal_get_stats() vs dev_get_tstats64()
> 
Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com>

[PATCH v3] net: openvswitch: use core API to update/provide stats

[Lev Stipakov]

Commit d3fd65484c781 ("net: core: add dev_sw_netstats_tx_add") has added
function "dev_sw_netstats_tx_add()" to update net device per-cpu TX
stats.

Use this function instead of own code.

While on it, remove internal_get_stats() and replace it
with dev_get_tstats64().

Signed-off-by: Lev Stipakov <lev@openvpn.net>
Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com>
---

 v3: no code changes, just send separate patch instead of series as
requested

 v2:
  - do not delete len variable and add comment why
  - replace internal_get_stats() vs dev_get_tstats64()

 net/openvswitch/vport-internal_dev.c | 29 +++++++---------------------
 1 file changed, 7 insertions(+), 22 deletions(-)

diff --git a/net/openvswitch/vport-internal_dev.c b/net/openvswitch/vport-internal_dev.c
index 1e30d8df3ba5..5b2ee9c1c00b 100644
--- a/net/openvswitch/vport-internal_dev.c
+++ b/net/openvswitch/vport-internal_dev.c
@@ -35,21 +35,18 @@ internal_dev_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	int len, err;
 
+	/* store len value because skb can be freed inside ovs_vport_receive() */
 	len = skb->len;
+
 	rcu_read_lock();
 	err = ovs_vport_receive(internal_dev_priv(netdev)->vport, skb, NULL);
 	rcu_read_unlock();
 
-	if (likely(!err)) {
-		struct pcpu_sw_netstats *tstats = this_cpu_ptr(netdev->tstats);
-
-		u64_stats_update_begin(&tstats->syncp);
-		tstats->tx_bytes += len;
-		tstats->tx_packets++;
-		u64_stats_update_end(&tstats->syncp);
-	} else {
+	if (likely(!err))
+		dev_sw_netstats_tx_add(netdev, 1, len);
+	else
 		netdev->stats.tx_errors++;
-	}
+
 	return NETDEV_TX_OK;
 }
 
@@ -83,24 +80,12 @@ static void internal_dev_destructor(struct net_device *dev)
 	ovs_vport_free(vport);
 }
 
-static void
-internal_get_stats(struct net_device *dev, struct rtnl_link_stats64 *stats)
-{
-	memset(stats, 0, sizeof(*stats));
-	stats->rx_errors  = dev->stats.rx_errors;
-	stats->tx_errors  = dev->stats.tx_errors;
-	stats->tx_dropped = dev->stats.tx_dropped;
-	stats->rx_dropped = dev->stats.rx_dropped;
-
-	dev_fetch_sw_netstats(stats, dev->tstats);
-}
-
 static const struct net_device_ops internal_dev_netdev_ops = {
 	.ndo_open = internal_dev_open,
 	.ndo_stop = internal_dev_stop,
 	.ndo_start_xmit = internal_dev_xmit,
 	.ndo_set_mac_address = eth_mac_addr,
-	.ndo_get_stats64 = internal_get_stats,
+	.ndo_get_stats64 = dev_get_tstats64,
 };
 
 static struct rtnl_link_ops internal_dev_link_ops __read_mostly = {
-- 
2.25.1

Re: [PATCH v3] net: openvswitch: use core API to update/provide stats

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Fri, 13 Nov 2020 23:53:36 +0200 you wrote:
> Commit d3fd65484c781 ("net: core: add dev_sw_netstats_tx_add") has added
> function "dev_sw_netstats_tx_add()" to update net device per-cpu TX
> stats.
> 
> Use this function instead of own code.
> 
> While on it, remove internal_get_stats() and replace it
> with dev_get_tstats64().
> 
> [...]

Here is the summary with links:
  - [v3] net: openvswitch: use core API to update/provide stats
    https://git.kernel.org/netdev/net-next/c/865e6ae02dd7

You are awesome, thank you!
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