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authorVladimir Oltean <vladimir.oltean@nxp.com>2021-06-21 19:42:18 +0300
committerDavid S. Miller <davem@davemloft.net>2021-06-21 12:50:20 -0700
commit88faba20e2100c1f367133af56612742ad37df08 (patch)
tree54b39a59d69c8c7294bf675f0e91520f27fce15d /crypto/asymmetric_keys
parent4e4ab7950044d195f6e3d4dac328f506badb6efa (diff)
downloadlinux-88faba20e2100c1f367133af56612742ad37df08.tar.bz2
net: dsa: targeted MTU notifiers should only match on one port
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@nxp.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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