Netdev Archive on
help / color / mirror / Atom feed
From: Kurt Kanzenbach <>
To: Vladimir Oltean <>,, Jakub Kicinski <>,
	"David S. Miller" <>
Cc: Florian Fainelli <>,
	Andrew Lunn <>,
	Vivien Didelot <>,
	Vladimir Oltean <>,
	Hauke Mehrtens <>,
	Egil Hjelmeland <>
Subject: Re: [PATCH net 1/4] net: dsa: hellcreek: fix broken backpressure in .port_fdb_dump
Date: Tue, 10 Aug 2021 13:39:36 +0200	[thread overview]
Message-ID: <87wnotle9z.fsf@kurt> (raw)
In-Reply-To: <>

[-- Attachment #1: Type: text/plain, Size: 1256 bytes --]

On Tue Aug 10 2021, Vladimir Oltean wrote:
> rtnl_fdb_dump() has logic to split a dump of PF_BRIDGE neighbors into
> multiple netlink skbs if the buffer provided by user space is too small
> (one buffer will typically handle a few hundred FDB entries).
> When the current buffer becomes full, nlmsg_put() in
> dsa_slave_port_fdb_do_dump() returns -EMSGSIZE and DSA saves the index
> of the last dumped FDB entry, returns to rtnl_fdb_dump() up to that
> point, and then the dump resumes on the same port with a new skb, and
> FDB entries up to the saved index are simply skipped.
> Since dsa_slave_port_fdb_do_dump() is pointed to by the "cb" passed to
> drivers, then drivers must check for the -EMSGSIZE error code returned
> by it. Otherwise, when a netlink skb becomes full, DSA will no longer
> save newly dumped FDB entries to it, but the driver will continue
> dumping. So FDB entries will be missing from the dump.
> Fix the broken backpressure by propagating the "cb" return code and
> allow rtnl_fdb_dump() to restart the FDB dump with a new skb.
> Fixes: e4b27ebc780f ("net: dsa: Add DSA driver for Hirschmann Hellcreek switches")
> Signed-off-by: Vladimir Oltean <>

Acked-by: Kurt Kanzenbach <>

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 861 bytes --]

  reply	other threads:[~2021-08-10 11:39 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-10 11:19 [PATCH net 0/4] Fix broken backpressure during FDB dump in DSA drivers Vladimir Oltean
2021-08-10 11:19 ` [PATCH net 1/4] net: dsa: hellcreek: fix broken backpressure in .port_fdb_dump Vladimir Oltean
2021-08-10 11:39   ` Kurt Kanzenbach [this message]
2021-08-10 11:19 ` [PATCH net 2/4] net: dsa: lan9303: " Vladimir Oltean
2021-08-10 11:19 ` [PATCH net 3/4] net: dsa: lantiq: " Vladimir Oltean
2021-08-10 11:19 ` [PATCH net 4/4] net: dsa: sja1105: " Vladimir Oltean
2021-08-10 12:20 ` [PATCH net 0/4] Fix broken backpressure during FDB dump in DSA drivers patchwork-bot+netdevbpf

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87wnotle9z.fsf@kurt \ \ \ \ \ \ \ \ \ \ \ \
    --subject='Re: [PATCH net 1/4] net: dsa: hellcreek: fix broken backpressure in .port_fdb_dump' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).