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Message-Id: <20210618183017.3340769-6-olteanv@gmail.com>
Date: Fri, 18 Jun 2021 21:30:16 +0300
From: Vladimir Oltean <olteanv@...il.com>
To: Jakub Kicinski <kuba@...nel.org>,
"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Cc: Florian Fainelli <f.fainelli@...il.com>,
Andrew Lunn <andrew@...n.ch>,
Vivien Didelot <vivien.didelot@...il.com>,
Vladimir Oltean <vladimir.oltean@....com>
Subject: [PATCH net-next 5/6] net: dsa: targeted MTU notifiers should only match on one port
From: Vladimir Oltean <vladimir.oltean@....com>
dsa_slave_change_mtu() calls dsa_port_mtu_change() twice:
- it sends a cross-chip notifier with the MTU of the CPU port which is
used to update the DSA links.
- it sends one targeted MTU notifier which is supposed to only match the
user port on which we are changing the MTU. The "propagate_upstream"
variable is used here to bypass the cross-chip notifier system from
switch.c
But due to a mistake, the second, targeted notifier matches not only on
the user port, but also on the DSA link which is a member of the same
switch, if that exists.
And because the DSA links of the entire dst were programmed in a
previous round to the largest_mtu via a "propagate_upstream == true"
notification, then the dsa_port_mtu_change(propagate_upstream == false)
call that is immediately upcoming will break the MTU on the one DSA link
which is chip-wise local to the dp whose MTU is changing right now.
Example given this daisy chain topology:
sw0p0 sw0p1 sw0p2 sw0p3 sw0p4
[ cpu ] [ user ] [ user ] [ dsa ] [ user ]
[ x ] [ ] [ ] [ x ] [ ]
|
+---------+
|
sw1p0 sw1p1 sw1p2 sw1p3 sw1p4
[ user ] [ user ] [ user ] [ dsa ] [ dsa ]
[ ] [ ] [ ] [ ] [ x ]
ip link set sw0p1 mtu 9000
ip link set sw1p1 mtu 9000 # at this stage, sw0p1 and sw1p1 can talk
# to one another using jumbo frames
ip link set sw0p2 mtu 1500 # this programs the sw0p3 DSA link first to
# the largest_mtu of 9000, then reprograms it to
# 1500 with the "propagate_upstream == false"
# notifier, breaking communication between
# sw0p1 and sw1p1
To escape from this situation, make the targeted match really match on a
single port - the user port, and rename the "propagate_upstream"
variable to "targeted_match" to clarify the intention and avoid future
issues.
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
net/dsa/dsa_priv.h | 4 ++--
net/dsa/port.c | 4 ++--
net/dsa/slave.c | 9 +++++----
net/dsa/switch.c | 9 ++++++---
4 files changed, 15 insertions(+), 11 deletions(-)
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index b8b17474b72b..b0811253d101 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -84,7 +84,7 @@ struct dsa_notifier_vlan_info {
/* DSA_NOTIFIER_MTU */
struct dsa_notifier_mtu_info {
- bool propagate_upstream;
+ bool targeted_match;
int sw_index;
int port;
int mtu;
@@ -200,7 +200,7 @@ int dsa_port_vlan_filtering(struct dsa_port *dp, bool vlan_filtering,
bool dsa_port_skip_vlan_configuration(struct dsa_port *dp);
int dsa_port_ageing_time(struct dsa_port *dp, clock_t ageing_clock);
int dsa_port_mtu_change(struct dsa_port *dp, int new_mtu,
- bool propagate_upstream);
+ bool targeted_match);
int dsa_port_fdb_add(struct dsa_port *dp, const unsigned char *addr,
u16 vid);
int dsa_port_fdb_del(struct dsa_port *dp, const unsigned char *addr,
diff --git a/net/dsa/port.c b/net/dsa/port.c
index 6379d66a6bb3..5c93f1e1a03d 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -567,11 +567,11 @@ int dsa_port_mrouter(struct dsa_port *dp, bool mrouter,
}
int dsa_port_mtu_change(struct dsa_port *dp, int new_mtu,
- bool propagate_upstream)
+ bool targeted_match)
{
struct dsa_notifier_mtu_info info = {
.sw_index = dp->ds->index,
- .propagate_upstream = propagate_upstream,
+ .targeted_match = targeted_match,
.port = dp->index,
.mtu = new_mtu,
};
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index ac2ca5f75af3..5e668e529575 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -1586,14 +1586,15 @@ int dsa_slave_change_mtu(struct net_device *dev, int new_mtu)
goto out_master_failed;
/* We only need to propagate the MTU of the CPU port to
- * upstream switches.
+ * upstream switches, so create a non-targeted notifier which
+ * updates all switches.
*/
- err = dsa_port_mtu_change(cpu_dp, cpu_mtu, true);
+ err = dsa_port_mtu_change(cpu_dp, cpu_mtu, false);
if (err)
goto out_cpu_failed;
}
- err = dsa_port_mtu_change(dp, new_mtu, false);
+ err = dsa_port_mtu_change(dp, new_mtu, true);
if (err)
goto out_port_failed;
@@ -1607,7 +1608,7 @@ int dsa_slave_change_mtu(struct net_device *dev, int new_mtu)
if (new_master_mtu != old_master_mtu)
dsa_port_mtu_change(cpu_dp, old_master_mtu -
dsa_tag_protocol_overhead(cpu_dp->tag_ops),
- true);
+ false);
out_cpu_failed:
if (new_master_mtu != old_master_mtu)
dev_set_mtu(master, old_master_mtu);
diff --git a/net/dsa/switch.c b/net/dsa/switch.c
index 8b601ced6b45..75f567390a6b 100644
--- a/net/dsa/switch.c
+++ b/net/dsa/switch.c
@@ -52,10 +52,13 @@ static int dsa_switch_ageing_time(struct dsa_switch *ds,
static bool dsa_switch_mtu_match(struct dsa_switch *ds, int port,
struct dsa_notifier_mtu_info *info)
{
- if (ds->index == info->sw_index)
- return (port == info->port) || dsa_is_dsa_port(ds, port);
+ if (ds->index == info->sw_index && port == info->port)
+ return true;
- if (!info->propagate_upstream)
+ /* Do not propagate to other switches in the tree if the notifier was
+ * targeted for a single switch.
+ */
+ if (info->targeted_match)
return false;
if (dsa_is_dsa_port(ds, port) || dsa_is_cpu_port(ds, port))
--
2.25.1
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