From: Vladimir Oltean <olteanv@gmail.com>
To: Alexander Duyck <alexanderduyck@fb.com>,
Jakub Kicinski <kuba@kernel.org>, Jiri Pirko <jiri@nvidia.com>,
Florian Fainelli <f.fainelli@gmail.com>
Cc: netdev@vger.kernel.org
Subject: Possible to use both dev_mc_sync and __dev_mc_sync?
Date: Mon, 21 Mar 2022 18:32:13 +0200 [thread overview]
Message-ID: <20220321163213.lrn5sk7m6grighbl@skbuf> (raw)
Hello,
Despite the similar names, the 2 functions above serve quite different
purposes, and as it happens, DSA needs to use both of them, each for its
own purpose.
static void dsa_slave_set_rx_mode(struct net_device *dev)
{
struct net_device *master = dsa_slave_to_master(dev);
struct dsa_port *dp = dsa_slave_to_port(dev);
struct dsa_switch *ds = dp->ds;
dev_mc_sync(master, dev); // DSA is a stacked device
dev_uc_sync(master, dev);
if (dsa_switch_supports_mc_filtering(ds))
__dev_mc_sync(dev, dsa_slave_sync_mc, dsa_slave_unsync_mc); // DSA is also a hardware device
if (dsa_switch_supports_uc_filtering(ds))
__dev_uc_sync(dev, dsa_slave_sync_uc, dsa_slave_unsync_uc);
}
What I'm noticing is that some addresses, for example 33:33:00:00:00:01
(added by addrconf.c as in6addr_linklocal_allnodes) are synced to the
master via dev_mc_sync(), but not to hardware by __dev_mc_sync().
Superficially, this is because dev_mc_sync() -> __hw_addr_sync_one()
will increase ha->sync_cnt to a non-zero value. Then, when __dev_mc_sync()
-> __hw_addr_sync_dev() checks ha->sync_cnt, it sees that it has been
"already synced" (not really), so it doesn't call the "sync" method
(dsa_slave_sync_mc) for this ha.
However I don't understand the deep reasons and I am confused by the
members of struct netdev_hw_addr (synced vs sync_cnt vs refcount).
I can't tell if this was supposed to work, given that "sync address to
another device" is conceptually a different kind of sync than "sync
address to hardware", so I'm a bit surprised that they share the same
variables.
Any ideas?
next reply other threads:[~2022-03-21 16:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-21 16:32 Vladimir Oltean [this message]
2022-03-21 18:37 ` Possible to use both dev_mc_sync and __dev_mc_sync? Alexander Duyck
2022-03-21 18:42 ` Vladimir Oltean
2022-03-21 18:45 ` Vladimir Oltean
2022-03-21 19:13 ` Alexander Duyck
2022-03-21 20:02 ` Jay Vosburgh
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