[PATCH net v2 0/6] mlxsw: Various fixes

[PATCH net v2 0/6] mlxsw: Various fixes

[Ido Schimmel]

From: Ido Schimmel <idosch@mellanox.com>

This patch set contains various fixes for mlxsw.

Patch #1 splits the init() callback between Spectrum-2 and Spectrum-3 in
order to avoid enforcing the same firmware version for both ASICs, as
this can't possibly work. Without this patch the driver cannot boot with
the Spectrum-3 ASIC.

Patches #2-#3 fix a long standing race condition that was recently
exposed while testing the driver on an emulator, which is very slow
compared to the actual hardware. The problem is explained in detail in
the commit messages.

Patch #4 fixes a selftest.

Patch #5 prevents offloaded qdiscs from presenting a non-zero backlog to
the user when the netdev is down. This is done by clearing the cached
backlog in the driver when the netdev goes down.

Patch #6 fixes qdisc statistics (backlog and tail drops) to also take
into account the multicast traffic classes.

v2:
* Patches #2-#3: use skb_cow_head() instead of skb_unshare() as
  suggested by Jakub. Remove unnecessary check regarding headroom
* Patches #5-#6: new

Ido Schimmel (3):
  mlxsw: spectrum: Do not enforce same firmware version for multiple
    ASICs
  mlxsw: spectrum: Do not modify cloned SKBs during xmit
  mlxsw: switchx2: Do not modify cloned SKBs during xmit

Petr Machata (3):
  selftests: mlxsw: qos_mc_aware: Fix mausezahn invocation
  mlxsw: spectrum: Wipe xstats.backlog of down ports
  mlxsw: spectrum_qdisc: Include MC TCs in Qdisc counters

 .../net/ethernet/mellanox/mlxsw/spectrum.c    | 54 ++++++++++++++-----
 .../ethernet/mellanox/mlxsw/spectrum_qdisc.c  | 30 ++++++++---
 .../net/ethernet/mellanox/mlxsw/switchx2.c    | 17 +++---
 .../drivers/net/mlxsw/qos_mc_aware.sh         |  8 ++-
 4 files changed, 76 insertions(+), 33 deletions(-)

-- 
2.24.1

[PATCH net v2 1/6] mlxsw: spectrum: Do not enforce same firmware version for multiple ASICs

[Ido Schimmel]

From: Ido Schimmel <idosch@mellanox.com>

In commit a72afb6879bb ("mlxsw: Enforce firmware version for
Spectrum-2") I added a required firmware version for Spectrum-2, but
missed the fact that mlxsw_sp2_init() is used by both Spectrum-2 and
Spectrum-3. This means that the same firmware version will be used for
both, which is wrong.

Fix this by creating a new init() callback for Spectrum-3.

Fixes: a72afb6879bb ("mlxsw: Enforce firmware version for Spectrum-2")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Tested-by: Shalom Toledo <shalomt@mellanox.com>
---
 .../net/ethernet/mellanox/mlxsw/spectrum.c    | 23 ++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index f7fd5e8fbf96..5408a964bd10 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -5132,6 +5132,27 @@ static int mlxsw_sp2_init(struct mlxsw_core *mlxsw_core,
 	return mlxsw_sp_init(mlxsw_core, mlxsw_bus_info, extack);
 }
 
+static int mlxsw_sp3_init(struct mlxsw_core *mlxsw_core,
+			  const struct mlxsw_bus_info *mlxsw_bus_info,
+			  struct netlink_ext_ack *extack)
+{
+	struct mlxsw_sp *mlxsw_sp = mlxsw_core_driver_priv(mlxsw_core);
+
+	mlxsw_sp->kvdl_ops = &mlxsw_sp2_kvdl_ops;
+	mlxsw_sp->afa_ops = &mlxsw_sp2_act_afa_ops;
+	mlxsw_sp->afk_ops = &mlxsw_sp2_afk_ops;
+	mlxsw_sp->mr_tcam_ops = &mlxsw_sp2_mr_tcam_ops;
+	mlxsw_sp->acl_tcam_ops = &mlxsw_sp2_acl_tcam_ops;
+	mlxsw_sp->nve_ops_arr = mlxsw_sp2_nve_ops_arr;
+	mlxsw_sp->mac_mask = mlxsw_sp2_mac_mask;
+	mlxsw_sp->rif_ops_arr = mlxsw_sp2_rif_ops_arr;
+	mlxsw_sp->sb_vals = &mlxsw_sp2_sb_vals;
+	mlxsw_sp->port_type_speed_ops = &mlxsw_sp2_port_type_speed_ops;
+	mlxsw_sp->ptp_ops = &mlxsw_sp2_ptp_ops;
+
+	return mlxsw_sp_init(mlxsw_core, mlxsw_bus_info, extack);
+}
+
 static void mlxsw_sp_fini(struct mlxsw_core *mlxsw_core)
 {
 	struct mlxsw_sp *mlxsw_sp = mlxsw_core_driver_priv(mlxsw_core);
@@ -5634,7 +5655,7 @@ static struct mlxsw_driver mlxsw_sp2_driver = {
 static struct mlxsw_driver mlxsw_sp3_driver = {
 	.kind				= mlxsw_sp3_driver_name,
 	.priv_size			= sizeof(struct mlxsw_sp),
-	.init				= mlxsw_sp2_init,
+	.init				= mlxsw_sp3_init,
 	.fini				= mlxsw_sp_fini,
 	.basic_trap_groups_set		= mlxsw_sp_basic_trap_groups_set,
 	.port_split			= mlxsw_sp_port_split,
-- 
2.24.1

[PATCH net v2 2/6] mlxsw: spectrum: Do not modify cloned SKBs during xmit

[Ido Schimmel]

From: Ido Schimmel <idosch@mellanox.com>

The driver needs to prepend a Tx header to each packet it is
transmitting. The header includes information such as the egress port
and traffic class.

The addition of the header requires the driver to modify the SKB's
header and therefore it must not be shared. Otherwise, we risk hitting
various race conditions.

For example, when a packet is flooded (cloned) by the bridge driver to
two switch ports swp1 and swp2:

t0 - mlxsw_sp_port_xmit() is called for swp1. Tx header is prepended with
     swp1's port number
t1 - mlxsw_sp_port_xmit() is called for swp2. Tx header is prepended with
     swp2's port number, overwriting swp1's port number
t2 - The device processes data buffer from t0. Packet is transmitted via
     swp2
t3 - The device processes data buffer from t1. Packet is transmitted via
     swp2

Usually, the device is fast enough and transmits the packet before its
Tx header is overwritten, but this is not the case in emulated
environments.

Fix this by making sure the SKB's header is writable by calling
skb_cow_head(). Since the function ensures we have headroom to push the
Tx header, the check further in the function can be removed.

v2:
* Use skb_cow_head() instead of skb_unshare() as suggested by Jakub
* Remove unnecessary check regarding headroom

Fixes: 56ade8fe3fe1 ("mlxsw: spectrum: Add initial support for Spectrum ASIC")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Shalom Toledo <shalomt@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index 5408a964bd10..2394c425b47d 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -860,23 +860,17 @@ static netdev_tx_t mlxsw_sp_port_xmit(struct sk_buff *skb,
 	u64 len;
 	int err;
 
+	if (skb_cow_head(skb, MLXSW_TXHDR_LEN)) {
+		this_cpu_inc(mlxsw_sp_port->pcpu_stats->tx_dropped);
+		dev_kfree_skb_any(skb);
+		return NETDEV_TX_OK;
+	}
+
 	memset(skb->cb, 0, sizeof(struct mlxsw_skb_cb));
 
 	if (mlxsw_core_skb_transmit_busy(mlxsw_sp->core, &tx_info))
 		return NETDEV_TX_BUSY;
 
-	if (unlikely(skb_headroom(skb) < MLXSW_TXHDR_LEN)) {
-		struct sk_buff *skb_orig = skb;
-
-		skb = skb_realloc_headroom(skb, MLXSW_TXHDR_LEN);
-		if (!skb) {
-			this_cpu_inc(mlxsw_sp_port->pcpu_stats->tx_dropped);
-			dev_kfree_skb_any(skb_orig);
-			return NETDEV_TX_OK;
-		}
-		dev_consume_skb_any(skb_orig);
-	}
-
 	if (eth_skb_pad(skb)) {
 		this_cpu_inc(mlxsw_sp_port->pcpu_stats->tx_dropped);
 		return NETDEV_TX_OK;
-- 
2.24.1

[PATCH net v2 3/6] mlxsw: switchx2: Do not modify cloned SKBs during xmit

[Ido Schimmel]

From: Ido Schimmel <idosch@mellanox.com>

The driver needs to prepend a Tx header to each packet it is
transmitting. The header includes information such as the egress port
and traffic class.

The addition of the header requires the driver to modify the SKB's
header and therefore it must not be shared. Otherwise, we risk hitting
various race conditions.

For example, when a packet is flooded (cloned) by the bridge driver to
two switch ports swp1 and swp2:

t0 - mlxsw_sp_port_xmit() is called for swp1. Tx header is prepended with
     swp1's port number
t1 - mlxsw_sp_port_xmit() is called for swp2. Tx header is prepended with
     swp2's port number, overwriting swp1's port number
t2 - The device processes data buffer from t0. Packet is transmitted via
     swp2
t3 - The device processes data buffer from t1. Packet is transmitted via
     swp2

Usually, the device is fast enough and transmits the packet before its
Tx header is overwritten, but this is not the case in emulated
environments.

Fix this by making sure the SKB's header is writable by calling
skb_cow_head(). Since the function ensures we have headroom to push the
Tx header, the check further in the function can be removed.

v2:
* Use skb_cow_head() instead of skb_unshare() as suggested by Jakub
* Remove unnecessary check regarding headroom

Fixes: 31557f0f9755 ("mlxsw: Introduce Mellanox SwitchX-2 ASIC support")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Shalom Toledo <shalomt@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/switchx2.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/switchx2.c b/drivers/net/ethernet/mellanox/mlxsw/switchx2.c
index de6cb22f68b1..f0e98ec8f1ee 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/switchx2.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/switchx2.c
@@ -299,22 +299,17 @@ static netdev_tx_t mlxsw_sx_port_xmit(struct sk_buff *skb,
 	u64 len;
 	int err;
 
+	if (skb_cow_head(skb, MLXSW_TXHDR_LEN)) {
+		this_cpu_inc(mlxsw_sx_port->pcpu_stats->tx_dropped);
+		dev_kfree_skb_any(skb);
+		return NETDEV_TX_OK;
+	}
+
 	memset(skb->cb, 0, sizeof(struct mlxsw_skb_cb));
 
 	if (mlxsw_core_skb_transmit_busy(mlxsw_sx->core, &tx_info))
 		return NETDEV_TX_BUSY;
 
-	if (unlikely(skb_headroom(skb) < MLXSW_TXHDR_LEN)) {
-		struct sk_buff *skb_orig = skb;
-
-		skb = skb_realloc_headroom(skb, MLXSW_TXHDR_LEN);
-		if (!skb) {
-			this_cpu_inc(mlxsw_sx_port->pcpu_stats->tx_dropped);
-			dev_kfree_skb_any(skb_orig);
-			return NETDEV_TX_OK;
-		}
-		dev_consume_skb_any(skb_orig);
-	}
 	mlxsw_sx_txhdr_construct(skb, &tx_info);
 	/* TX header is consumed by HW on the way so we shouldn't count its
 	 * bytes as being sent.
-- 
2.24.1

[PATCH net v2 4/6] selftests: mlxsw: qos_mc_aware: Fix mausezahn invocation

[Ido Schimmel]

From: Petr Machata <petrm@mellanox.com>

Mausezahn does not recognize "own" as a keyword on source IP address. As a
result, the MC stream is not running at all, and therefore no UC
degradation can be observed even in principle.

Fix the invocation, and tighten the test: due to the minimum shaper
configured at the MC TCs, we always expect about 20% degradation. Fail the
test if it is lower.

Fixes: 573363a68f27 ("selftests: mlxsw: Add qos_lib.sh")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Reported-by: Amit Cohen <amitc@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
---
 tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh b/tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh
index 47315fe48d5a..24dd8ed48580 100755
--- a/tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh
+++ b/tools/testing/selftests/drivers/net/mlxsw/qos_mc_aware.sh
@@ -232,7 +232,7 @@ test_mc_aware()
 	stop_traffic
 	local ucth1=${uc_rate[1]}
 
-	start_traffic $h1 own bc bc
+	start_traffic $h1 192.0.2.65 bc bc
 
 	local d0=$(date +%s)
 	local t0=$(ethtool_stats_get $h3 rx_octets_prio_0)
@@ -254,7 +254,11 @@ test_mc_aware()
 			ret = 100 * ($ucth1 - $ucth2) / $ucth1
 			if (ret > 0) { ret } else { 0 }
 		    ")
-	check_err $(bc <<< "$deg > 25")
+
+	# Minimum shaper of 200Mbps on MC TCs should cause about 20% of
+	# degradation on 1Gbps link.
+	check_err $(bc <<< "$deg < 15") "Minimum shaper not in effect"
+	check_err $(bc <<< "$deg > 25") "MC traffic degrades UC performance too much"
 
 	local interval=$((d1 - d0))
 	local mc_ir=$(rate $u0 $u1 $interval)
-- 
2.24.1

[PATCH net v2 5/6] mlxsw: spectrum: Wipe xstats.backlog of down ports

[Ido Schimmel]

From: Petr Machata <petrm@mellanox.com>

Per-port counter cache used by Qdiscs is updated periodically, unless the
port is down. The fact that the cache is not updated for down ports is no
problem for most counters, which are relative in nature. However, backlog
is absolute in nature, and if there is a non-zero value in the cache around
the time that the port goes down, that value just stays there. This value
then leaks to offloaded Qdiscs that report non-zero backlog even if
there (obviously) is no traffic.

The HW does not keep backlog of a downed port, so do likewise: as the port
goes down, wipe the backlog value from xstats.

Fixes: 075ab8adaf4e ("mlxsw: spectrum: Collect tclass related stats periodically")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index 2394c425b47d..8ed15199eb4f 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -1209,6 +1209,9 @@ static void update_stats_cache(struct work_struct *work)
 			     periodic_hw_stats.update_dw.work);
 
 	if (!netif_carrier_ok(mlxsw_sp_port->dev))
+		/* Note: mlxsw_sp_port_down_wipe_counters() clears the cache as
+		 * necessary when port goes down.
+		 */
 		goto out;
 
 	mlxsw_sp_port_get_hw_stats(mlxsw_sp_port->dev,
@@ -4318,6 +4321,15 @@ static int mlxsw_sp_port_unsplit(struct mlxsw_core *mlxsw_core, u8 local_port,
 	return 0;
 }
 
+static void
+mlxsw_sp_port_down_wipe_counters(struct mlxsw_sp_port *mlxsw_sp_port)
+{
+	int i;
+
+	for (i = 0; i < TC_MAX_QUEUE; i++)
+		mlxsw_sp_port->periodic_hw_stats.xstats.backlog[i] = 0;
+}
+
 static void mlxsw_sp_pude_event_func(const struct mlxsw_reg_info *reg,
 				     char *pude_pl, void *priv)
 {
@@ -4339,6 +4351,7 @@ static void mlxsw_sp_pude_event_func(const struct mlxsw_reg_info *reg,
 	} else {
 		netdev_info(mlxsw_sp_port->dev, "link down\n");
 		netif_carrier_off(mlxsw_sp_port->dev);
+		mlxsw_sp_port_down_wipe_counters(mlxsw_sp_port);
 	}
 }
 
-- 
2.24.1

[PATCH net v2 6/6] mlxsw: spectrum_qdisc: Include MC TCs in Qdisc counters

[Ido Schimmel]

From: Petr Machata <petrm@mellanox.com>

mlxsw configures Spectrum in such a way that BUM traffic is passed not
through its nominal traffic class TC, but through its MC counterpart TC+8.
However, when collecting statistics, Qdiscs only look at the nominal TC and
ignore the MC TC.

Add two helpers to compute the value for logical TC from the constituents,
one for backlog, the other for tail drops. Use them throughout instead of
going through the xstats pointer directly.

Counters for TX bytes and packets are deduced from packet priority
counters, and therefore already include BUM traffic. wred_drop counter is
irrelevant on MC TCs, because RED is not enabled on them.

Fixes: 7b8195306694 ("mlxsw: spectrum: Configure MC-aware mode on mlxsw ports")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
---
 .../ethernet/mellanox/mlxsw/spectrum_qdisc.c  | 30 ++++++++++++++-----
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
index 46d43cfd04e9..0124bfe1963b 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
@@ -195,6 +195,20 @@ mlxsw_sp_qdisc_get_xstats(struct mlxsw_sp_port *mlxsw_sp_port,
 	return -EOPNOTSUPP;
 }
 
+static u64
+mlxsw_sp_xstats_backlog(struct mlxsw_sp_port_xstats *xstats, int tclass_num)
+{
+	return xstats->backlog[tclass_num] +
+	       xstats->backlog[tclass_num + 8];
+}
+
+static u64
+mlxsw_sp_xstats_tail_drop(struct mlxsw_sp_port_xstats *xstats, int tclass_num)
+{
+	return xstats->tail_drop[tclass_num] +
+	       xstats->tail_drop[tclass_num + 8];
+}
+
 static void
 mlxsw_sp_qdisc_bstats_per_priority_get(struct mlxsw_sp_port_xstats *xstats,
 				       u8 prio_bitmap, u64 *tx_packets,
@@ -269,7 +283,7 @@ mlxsw_sp_setup_tc_qdisc_red_clean_stats(struct mlxsw_sp_port *mlxsw_sp_port,
 					       &stats_base->tx_bytes);
 	red_base->prob_mark = xstats->ecn;
 	red_base->prob_drop = xstats->wred_drop[tclass_num];
-	red_base->pdrop = xstats->tail_drop[tclass_num];
+	red_base->pdrop = mlxsw_sp_xstats_tail_drop(xstats, tclass_num);
 
 	stats_base->overlimits = red_base->prob_drop + red_base->prob_mark;
 	stats_base->drops = red_base->prob_drop + red_base->pdrop;
@@ -370,7 +384,8 @@ mlxsw_sp_qdisc_get_red_xstats(struct mlxsw_sp_port *mlxsw_sp_port,
 
 	early_drops = xstats->wred_drop[tclass_num] - xstats_base->prob_drop;
 	marks = xstats->ecn - xstats_base->prob_mark;
-	pdrops = xstats->tail_drop[tclass_num] - xstats_base->pdrop;
+	pdrops = mlxsw_sp_xstats_tail_drop(xstats, tclass_num) -
+		 xstats_base->pdrop;
 
 	res->pdrop += pdrops;
 	res->prob_drop += early_drops;
@@ -403,9 +418,10 @@ mlxsw_sp_qdisc_get_red_stats(struct mlxsw_sp_port *mlxsw_sp_port,
 
 	overlimits = xstats->wred_drop[tclass_num] + xstats->ecn -
 		     stats_base->overlimits;
-	drops = xstats->wred_drop[tclass_num] + xstats->tail_drop[tclass_num] -
+	drops = xstats->wred_drop[tclass_num] +
+		mlxsw_sp_xstats_tail_drop(xstats, tclass_num) -
 		stats_base->drops;
-	backlog = xstats->backlog[tclass_num];
+	backlog = mlxsw_sp_xstats_backlog(xstats, tclass_num);
 
 	_bstats_update(stats_ptr->bstats, tx_bytes, tx_packets);
 	stats_ptr->qstats->overlimits += overlimits;
@@ -576,9 +592,9 @@ mlxsw_sp_qdisc_get_prio_stats(struct mlxsw_sp_port *mlxsw_sp_port,
 	tx_packets = stats->tx_packets - stats_base->tx_packets;
 
 	for (i = 0; i < IEEE_8021QAZ_MAX_TCS; i++) {
-		drops += xstats->tail_drop[i];
+		drops += mlxsw_sp_xstats_tail_drop(xstats, i);
 		drops += xstats->wred_drop[i];
-		backlog += xstats->backlog[i];
+		backlog += mlxsw_sp_xstats_backlog(xstats, i);
 	}
 	drops = drops - stats_base->drops;
 
@@ -614,7 +630,7 @@ mlxsw_sp_setup_tc_qdisc_prio_clean_stats(struct mlxsw_sp_port *mlxsw_sp_port,
 
 	stats_base->drops = 0;
 	for (i = 0; i < IEEE_8021QAZ_MAX_TCS; i++) {
-		stats_base->drops += xstats->tail_drop[i];
+		stats_base->drops += mlxsw_sp_xstats_tail_drop(xstats, i);
 		stats_base->drops += xstats->wred_drop[i];
 	}
 
-- 
2.24.1

Re: [PATCH net v2 0/6] mlxsw: Various fixes

[David Miller]

From: Ido Schimmel <idosch@idosch.org>
Date: Wed, 15 Jan 2020 13:53:43 +0200

> This patch set contains various fixes for mlxsw.

Series applied, thanks Ido.