diff options
| author | Vladimir Oltean <vladimir.oltean@nxp.com> | 2023-03-14 20:24:04 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2023-03-16 17:39:42 +0000 |
| commit | 636e8adf7878eab3614250234341bde45537f47a (patch) | |
| tree | e28adb51117ca9a173cfa5d52aaf9221044598bd /net/dsa/slave.c | |
| parent | b830c9642386867863ac64295185f896ff2928ac (diff) | |
| download | linux-636e8adf7878eab3614250234341bde45537f47a.tar.gz linux-636e8adf7878eab3614250234341bde45537f47a.tar.bz2 linux-636e8adf7878eab3614250234341bde45537f47a.zip | |
net: dsa: don't error out when drivers return ETH_DATA_LEN in .port_max_mtu()
Currently, when dsa_slave_change_mtu() is called on a user port where
dev->max_mtu is 1500 (as returned by ds->ops->port_max_mtu()), the code
will stumble upon this check:
if (new_master_mtu > mtu_limit)
return -ERANGE;
because new_master_mtu is adjusted for the tagger overhead but mtu_limit
is not.
But it would be good if the logic went through, for example if the DSA
master really depends on an MTU adjustment to accept DSA-tagged frames.
To make the code pass through the check, we need to adjust mtu_limit for
the overhead as well, if the minimum restriction was caused by the DSA
user port's MTU (dev->max_mtu). A DSA user port MTU and a DSA master MTU
are always offset by the protocol overhead.
Currently no drivers return 1500 .port_max_mtu(), but this is only
temporary and a bug in itself - mv88e6xxx should have done that, but
since commit b9c587fed61c ("dsa: mv88e6xxx: Include tagger overhead when
setting MTU for DSA and CPU ports") it no longer does. This is a
preparation for fixing that.
Fixes: bfcb813203e6 ("net: dsa: configure the MTU for switch ports")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dsa/slave.c')
| -rw-r--r-- | net/dsa/slave.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/net/dsa/slave.c b/net/dsa/slave.c index 6957971c2db2..cac17183589f 100644 --- a/net/dsa/slave.c +++ b/net/dsa/slave.c @@ -1933,6 +1933,7 @@ int dsa_slave_change_mtu(struct net_device *dev, int new_mtu) int new_master_mtu; int old_master_mtu; int mtu_limit; + int overhead; int cpu_mtu; int err; @@ -1961,9 +1962,10 @@ int dsa_slave_change_mtu(struct net_device *dev, int new_mtu) largest_mtu = slave_mtu; } - mtu_limit = min_t(int, master->max_mtu, dev->max_mtu); + overhead = dsa_tag_protocol_overhead(cpu_dp->tag_ops); + mtu_limit = min_t(int, master->max_mtu, dev->max_mtu + overhead); old_master_mtu = master->mtu; - new_master_mtu = largest_mtu + dsa_tag_protocol_overhead(cpu_dp->tag_ops); + new_master_mtu = largest_mtu + overhead; if (new_master_mtu > mtu_limit) return -ERANGE; @@ -1998,8 +2000,7 @@ int dsa_slave_change_mtu(struct net_device *dev, int new_mtu) out_port_failed: if (new_master_mtu != old_master_mtu) - dsa_port_mtu_change(cpu_dp, old_master_mtu - - dsa_tag_protocol_overhead(cpu_dp->tag_ops)); + dsa_port_mtu_change(cpu_dp, old_master_mtu - overhead); out_cpu_failed: if (new_master_mtu != old_master_mtu) dev_set_mtu(master, old_master_mtu); |