linux-toradex.git/net/dsa/dsa.c, branch v5.14-rc6

net: dsa: allow changing the tag protocol via the "tagging" device attribute

2021-01-30T05:24:39+00:00

Currently DSA exposes the following sysfs:
$ cat /sys/class/net/eno2/dsa/tagging
ocelot

which is a read-only device attribute, introduced in the kernel as
commit 98cdb4807123 ("net: dsa: Expose tagging protocol to user-space"),
and used by libpcap since its commit 993db3800d7d ("Add support for DSA
link-layer types").

It would be nice if we could extend this device attribute by making it
writable:
$ echo ocelot-8021q > /sys/class/net/eno2/dsa/tagging

This is useful with DSA switches that can make use of more than one
tagging protocol. It may be useful in dsa_loop in the future too, to
perform offline testing of various taggers, or for changing between dsa
and edsa on Marvell switches, if that is desirable.

In terms of implementation, drivers can support this feature by
implementing .change_tag_protocol, which should always leave the switch
in a consistent state: either with the new protocol if things went well,
or with the old one if something failed. Teardown of the old protocol,
if necessary, must be handled by the driver.

Some things remain as before:
- The .get_tag_protocol is currently only called at probe time, to load
  the initial tagging protocol driver. Nonetheless, new drivers should
  report the tagging protocol in current use now.
- The driver should manage by itself the initial setup of tagging
  protocol, no later than the .setup() method, as well as destroying
  resources used by the last tagger in use, no earlier than the
  .teardown() method.

For multi-switch DSA trees, error handling is a bit more complicated,
since e.g. the 5th out of 7 switches may fail to change the tag
protocol. When that happens, a revert to the original tag protocol is
attempted, but that may fail too, leaving the tree in an inconsistent
state despite each individual switch implementing .change_tag_protocol
transactionally. Since the intersection between drivers that implement
.change_tag_protocol and drivers that support D in DSA is currently the
empty set, the possibility for this error to happen is ignored for now.

Testing:

$ insmod mscc_felix.ko
[   79.549784] mscc_felix 0000:00:00.5: Adding to iommu group 14
[   79.565712] mscc_felix 0000:00:00.5: Failed to register DSA switch: -517
$ insmod tag_ocelot.ko
$ rmmod mscc_felix.ko
$ insmod mscc_felix.ko
[   97.261724] libphy: VSC9959 internal MDIO bus: probed
[   97.267363] mscc_felix 0000:00:00.5: Found PCS at internal MDIO address 0
[   97.274998] mscc_felix 0000:00:00.5: Found PCS at internal MDIO address 1
[   97.282561] mscc_felix 0000:00:00.5: Found PCS at internal MDIO address 2
[   97.289700] mscc_felix 0000:00:00.5: Found PCS at internal MDIO address 3
[   97.599163] mscc_felix 0000:00:00.5 swp0 (uninitialized): PHY [0000:00:00.3:10] driver [Microsemi GE VSC8514 SyncE] (irq=POLL)
[   97.862034] mscc_felix 0000:00:00.5 swp1 (uninitialized): PHY [0000:00:00.3:11] driver [Microsemi GE VSC8514 SyncE] (irq=POLL)
[   97.950731] mscc_felix 0000:00:00.5 swp0: configuring for inband/qsgmii link mode
[   97.964278] 8021q: adding VLAN 0 to HW filter on device swp0
[   98.146161] mscc_felix 0000:00:00.5 swp2 (uninitialized): PHY [0000:00:00.3:12] driver [Microsemi GE VSC8514 SyncE] (irq=POLL)
[   98.238649] mscc_felix 0000:00:00.5 swp1: configuring for inband/qsgmii link mode
[   98.251845] 8021q: adding VLAN 0 to HW filter on device swp1
[   98.433916] mscc_felix 0000:00:00.5 swp3 (uninitialized): PHY [0000:00:00.3:13] driver [Microsemi GE VSC8514 SyncE] (irq=POLL)
[   98.485542] mscc_felix 0000:00:00.5: configuring for fixed/internal link mode
[   98.503584] mscc_felix 0000:00:00.5: Link is Up - 2.5Gbps/Full - flow control rx/tx
[   98.527948] device eno2 entered promiscuous mode
[   98.544755] DSA: tree 0 setup

$ ping 10.0.0.1
PING 10.0.0.1 (10.0.0.1): 56 data bytes
64 bytes from 10.0.0.1: seq=0 ttl=64 time=2.337 ms
64 bytes from 10.0.0.1: seq=1 ttl=64 time=0.754 ms
^C
 -  10.0.0.1 ping statistics  -
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 0.754/1.545/2.337 ms

$ cat /sys/class/net/eno2/dsa/tagging
ocelot
$ cat ./test_ocelot_8021q.sh
        #!/bin/bash

        ip link set swp0 down
        ip link set swp1 down
        ip link set swp2 down
        ip link set swp3 down
        ip link set swp5 down
        ip link set eno2 down
        echo ocelot-8021q > /sys/class/net/eno2/dsa/tagging
        ip link set eno2 up
        ip link set swp0 up
        ip link set swp1 up
        ip link set swp2 up
        ip link set swp3 up
        ip link set swp5 up
$ ./test_ocelot_8021q.sh
./test_ocelot_8021q.sh: line 9: echo: write error: Protocol not available
$ rmmod tag_ocelot.ko
rmmod: can't unload module 'tag_ocelot': Resource temporarily unavailable
$ insmod tag_ocelot_8021q.ko
$ ./test_ocelot_8021q.sh
$ cat /sys/class/net/eno2/dsa/tagging
ocelot-8021q
$ rmmod tag_ocelot.ko
$ rmmod tag_ocelot_8021q.ko
rmmod: can't unload module 'tag_ocelot_8021q': Resource temporarily unavailable
$ ping 10.0.0.1
PING 10.0.0.1 (10.0.0.1): 56 data bytes
64 bytes from 10.0.0.1: seq=0 ttl=64 time=0.953 ms
64 bytes from 10.0.0.1: seq=1 ttl=64 time=0.787 ms
64 bytes from 10.0.0.1: seq=2 ttl=64 time=0.771 ms
$ rmmod mscc_felix.ko
[  645.544426] mscc_felix 0000:00:00.5: Link is Down
[  645.838608] DSA: tree 0 torn down
$ rmmod tag_ocelot_8021q.ko

Signed-off-by: Vladimir Oltean 
Signed-off-by: Jakub Kicinski

net: dsa: tag_dsa: Support reception of packets from LAG devices

2021-01-15T01:11:56+00:00

Packets ingressing on a LAG that egress on the CPU port, which are not
classified as management, will have a FORWARD tag that does not
contain the normal source device/port tuple. Instead the trunk bit
will be set, and the port field holds the LAG id.

Since the exact source port information is not available in the tag,
frames are injected directly on the LAG interface and thus do never
pass through any DSA port interface on ingress.

Management frames (TO_CPU) are not affected and will pass through the
DSA port interface as usual.

Signed-off-by: Tobias Waldekranz 
Reviewed-by: Florian Fainelli 
Reviewed-by: Vladimir Oltean 
Signed-off-by: Jakub Kicinski

net: dsa: remove the DSA specific notifiers

2021-01-07T23:42:07+00:00

This effectively reverts commit 60724d4bae14 ("net: dsa: Add support for
DSA specific notifiers"). The reason is that since commit 2f1e8ea726e9
("net: dsa: link interfaces with the DSA master to get rid of lockdep
warnings"), it appears that there is a generic way to achieve the same
purpose. The only user thus far, the Broadcom SYSTEMPORT driver, was
converted to use the generic notifiers.

Signed-off-by: Vladimir Oltean 
Acked-by: Florian Fainelli 
Signed-off-by: Jakub Kicinski

net: dsa: use net core stats64 handling

2020-11-10T01:50:27+00:00

Use netdev->tstats instead of a member of dsa_slave_priv for storing
a pointer to the per-cpu counters. This allows us to use core
functionality for statistics handling.

Reviewed-by: Florian Fainelli 
Tested-by: Vladimir Oltean 
Signed-off-by: Heiner Kallweit 
Signed-off-by: Jakub Kicinski

net: dsa: Add devlink port regions support to DSA

2020-10-04T21:38:53+00:00

Allow DSA drivers to make use of devlink port regions, via simple
wrappers.

Reviewed-by: Vladimir Oltean 
Tested-by: Vladimir Oltean 
Signed-off-by: Andrew Lunn 
Reviewed-by: Florian Fainelli 
Signed-off-by: David S. Miller

net: dsa: Call dsa_untag_bridge_pvid() from dsa_switch_rcv()

2020-10-02T20:36:07+00:00

When a DSA switch driver needs to call dsa_untag_bridge_pvid(), it can
set dsa_switch::untag_brige_pvid to indicate this is necessary.

This is a pre-requisite to making sure that we are always calling
dsa_untag_bridge_pvid() after eth_type_trans() has been called.

Signed-off-by: Florian Fainelli 
Reviewed-by: Vladimir Oltean 
Signed-off-by: David S. Miller

net: dsa: Add devlink regions support to DSA

2020-09-19T01:17:45+00:00

Allow DSA drivers to make use of devlink regions, via simple wrappers.

Reviewed-by: Florian Fainelli 
Signed-off-by: Andrew Lunn 
Signed-off-by: David S. Miller

net: dsa: Add helper to convert from devlink to ds

2020-09-19T01:17:45+00:00

Given a devlink instance, return the dsa switch it is associated to.

Reviewed-by: Florian Fainelli 
Signed-off-by: Andrew Lunn 
Signed-off-by: David S. Miller

net: dsa: introduce a dsa_port_from_netdev public helper

2020-05-08T00:31:57+00:00

As its implementation shows, this is synonimous with calling
dsa_slave_dev_check followed by dsa_slave_to_port, so it is quite simple
already and provides functionality which is already there.

However there is now a need for these functions outside dsa_priv.h, for
example in drivers that perform mirroring and redirection through
tc-flower offloads (they are given raw access to the flow_cls_offload
structure), where they need to call this function on act->dev.

But simply exporting dsa_slave_to_port would make it non-inline and
would result in an extra function call in the hotpath, as can be seen
for example in sja1105:

Before:

000006dc :
{
 6dc:	e92d4ff0 	push	{r4, r5, r6, r7, r8, r9, sl, fp, lr}
 6e0:	e1a04000 	mov	r4, r0
 6e4:	e591958c 	ldr	r9, [r1, #1420]	; 0x58c <- Inline dsa_slave_to_port
 6e8:	e1a05001 	mov	r5, r1
 6ec:	e24dd004 	sub	sp, sp, #4
	u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index);
 6f0:	e1c901d8 	ldrd	r0, [r9, #24]
 6f4:	ebfffffe 	bl	0 
			6f4: R_ARM_CALL	dsa_8021q_tx_vid
	u8 pcp = netdev_txq_to_tc(netdev, queue_mapping);
 6f8:	e1d416b0 	ldrh	r1, [r4, #96]	; 0x60
	u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index);
 6fc:	e1a08000 	mov	r8, r0

After:

000006e4 :
{
 6e4:	e92d4ff0 	push	{r4, r5, r6, r7, r8, r9, sl, fp, lr}
 6e8:	e1a04000 	mov	r4, r0
 6ec:	e24dd004 	sub	sp, sp, #4
	struct dsa_port *dp = dsa_slave_to_port(netdev);
 6f0:	e1a00001 	mov	r0, r1
{
 6f4:	e1a05001 	mov	r5, r1
	struct dsa_port *dp = dsa_slave_to_port(netdev);
 6f8:	ebfffffe 	bl	0 
			6f8: R_ARM_CALL	dsa_slave_to_port
 6fc:	e1a09000 	mov	r9, r0
	u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index);
 700:	e1c001d8 	ldrd	r0, [r0, #24]
 704:	ebfffffe 	bl	0 
			704: R_ARM_CALL	dsa_8021q_tx_vid

Because we want to avoid possible performance regressions, introduce
this new function which is designed to be public.

Suggested-by: Vivien Didelot 
Signed-off-by: Vladimir Oltean 
Reviewed-by: Vivien Didelot 
Signed-off-by: David S. Miller

net: dsa: add GRO support via gro_cells

2020-04-23T19:32:13+00:00

gro_cells lib is used by different encapsulating netdevices, such as
geneve, macsec, vxlan etc. to speed up decapsulated traffic processing.
CPU tag is a sort of "encapsulation", and we can use the same mechs to
greatly improve overall DSA performance.
skbs are passed to the GRO layer after removing CPU tags, so we don't
need any new packet offload types as it was firstly proposed by me in
the first GRO-over-DSA variant [1].

The size of struct gro_cells is sizeof(void *), so hot struct
dsa_slave_priv becomes only 4/8 bytes bigger, and all critical fields
remain in one 32-byte cacheline.
The other positive side effect is that drivers for network devices
that can be shipped as CPU ports of DSA-driven switches can now use
napi_gro_frags() to pass skbs to kernel. Packets built that way are
completely non-linear and are likely being dropped without GRO.

This was tested on to-be-mainlined-soon Ethernet driver that uses
napi_gro_frags(), and the overall performance was on par with the
variant from [1], sometimes even better due to minimal overhead.
net.core.gro_normal_batch tuning may help to push it to the limit
on particular setups and platforms.

iperf3 IPoE VLAN NAT TCP forwarding (port1.218 -> port0) setup
on 1.2 GHz MIPS board:

5.7-rc2 baseline:

[ID]  Interval         Transfer     Bitrate        Retr
[ 5]  0.00-120.01 sec  9.00 GBytes  644 Mbits/sec  413  sender
[ 5]  0.00-120.00 sec  8.99 GBytes  644 Mbits/sec       receiver

Iface      RX packets  TX packets
eth0       7097731     7097702
port0      426050      6671829
port1      6671681     425862
port1.218  6671677     425851

With this patch:

[ID]  Interval         Transfer     Bitrate        Retr
[ 5]  0.00-120.01 sec  12.2 GBytes  870 Mbits/sec  122  sender
[ 5]  0.00-120.00 sec  12.2 GBytes  870 Mbits/sec       receiver

Iface      RX packets  TX packets
eth0       9474792     9474777
port0      455200      353288
port1      9019592     455035
port1.218  353144      455024

v2:
 - Add some performance examples in the commit message;
 - No functional changes.

[1] https://lore.kernel.org/netdev/20191230143028.27313-1-alobakin@dlink.ru/

Signed-off-by: Alexander Lobakin 
Signed-off-by: David S. Miller