Re: [RFC PATCH net-next 0/7] DSA master state tracking

On Thu, Dec 09, 2021 at 05:33:17PM +0000, Vladimir Oltean wrote:

On Thu, Dec 09, 2021 at 03:44:14PM +0100, Ansuel Smith wrote:

quoted

On Thu, Dec 09, 2021 at 02:28:30PM +0000, Vladimir Oltean wrote:

quoted

On Thu, Dec 09, 2021 at 04:05:59AM +0100, Ansuel Smith wrote:

quoted

On Thu, Dec 09, 2021 at 12:32:23AM +0200, Vladimir Oltean wrote:

quoted

This patch set is provided solely for review purposes (therefore not to
be applied anywhere) and for Ansuel to test whether they resolve the
slowdown reported here:
https://patchwork.kernel.org/project/netdevbpf/cover/20211207145942.7444-1-ansuelsmth@gmail.com/

It does conflict with net-next due to other patches that are in my tree,
and which were also posted here and would need to be picked ("Rework DSA
bridge TX forwarding offload API"):
https://patchwork.kernel.org/project/netdevbpf/cover/20211206165758.1553882-1-vladimir.oltean@nxp.com/

Additionally, for Ansuel's work there is also a logical dependency with
this series ("Replace DSA dp->priv with tagger-owned storage"):
https://patchwork.kernel.org/project/netdevbpf/cover/20211208200504.3136642-1-vladimir.oltean@nxp.com/

To get both dependency series, the following commands should be sufficient:
git b4 20211206165758.1553882-1-vladimir.oltean@nxp.com
git b4 20211208200504.3136642-1-vladimir.oltean@nxp.com

where "git b4" is an alias in ~/.gitconfig:
[b4]
	midmask = https://lore.kernel.org/r/%25s
[alias]
	b4 = "!f() { b4 am -t -o - $@ | git am -3; }; f"

The patches posted here are mainly to offer a consistent
"master_up"/"master_going_down" chain of events to switches, without
duplicates, and always starting with "master_up" and ending with
"master_going_down". This way, drivers should know when they can perform
Ethernet-based register access.

Vladimir Oltean (7):
  net: dsa: only bring down user ports assigned to a given DSA master
  net: dsa: refactor the NETDEV_GOING_DOWN master tracking into separate
    function
  net: dsa: use dsa_tree_for_each_user_port in
    dsa_tree_master_going_down()
  net: dsa: provide switch operations for tracking the master state
  net: dsa: stop updating master MTU from master.c
  net: dsa: hold rtnl_mutex when calling dsa_master_{setup,teardown}
  net: dsa: replay master state events in
    dsa_tree_{setup,teardown}_master

 include/net/dsa.h  |  8 +++++++
 net/dsa/dsa2.c     | 52 ++++++++++++++++++++++++++++++++++++++++++++--
 net/dsa/dsa_priv.h | 11 ++++++++++
 net/dsa/master.c   | 29 +++-----------------------
 net/dsa/slave.c    | 32 +++++++++++++++-------------
 net/dsa/switch.c   | 29 ++++++++++++++++++++++++++
 6 files changed, 118 insertions(+), 43 deletions(-)

-- 
2.25.1

I applied this patch and it does work correctly. Sadly the problem is
not solved and still the packet are not tracked correctly. What I notice
is that everything starts to work as soon as the master is set to
promiiscuous mode. Wonder if we should track that event instead of
simple up?

Here is a bootlog [0]. I added some log when the function timeouts and when
master up is actually called.
Current implementation for this is just a bool that is set to true on
master up and false on master going down. (final version should use
locking to check if an Ethernet transation is in progress)

[0] https://pastebin.com/7w2kgG7a

This is strange. What MAC DA do the ack packets have? Could you give us
a pcap with the request and reply packets (not necessarily now)?

If you want I can give you a pcap from a router bootup to the setup with
no ethernet cable attached. I notice the switch sends some packet at the
bootup for some reason but they are not Ethernet mdio packet or other
type. It seems they are not even tagged (doesn't have qca tag) as the
header mode is disabled by default)
Let me know if you need just a pcap for the Ethernet mdio transaction or
from a bootup. I assume it would be better from a bootup? (they are not
tons of packet and the mdio Ethernet ones are easy to notice.)

Anything that contains some request and response packets should do, as
long as they're relatively easy to spot. But as stated, this can wait
for a while, I don't think that promiscuity is the issue, after your
second reply.

Ok will send a pcap. Any preferred way to send it?

quoted

quoted

Can you try to set ".promisc_on_master = true" in qca_netdev_ops?

I already tried and here [0] is a log. I notice with promisc_on_master
the "eth0 entered promiscuous mode" is missing. Is that correct?
Unless I was tired and misread the code, the info should be printed
anyway. Also looking at the comments for promisc_on_master I don't think
that should be applied to this tagger.

[0] https://pastebin.com/MN2ttVpr

It isn't missing, it's right there on line 11.

Oww didn't notice that!

I think the problem is that we also need to track the operstate of the
master (netif_oper_up via NETDEV_CHANGE) before declaring it as good to go.
You can see that this is exactly the line after which the timeouts disappear:

[    7.146901] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready

I didn't really want to go there, because now I'm not sure how to
synthesize the information for the switch drivers to consume it.
Anyway I've prepared a v2 patchset and I'll send it out very soon.

Wonder if we should leave the driver decide when it's ready by parsing
the different state? (And change
the up ops to something like a generic change?)

-- 
	Ansuel