This is a note to let you know that I've just added the patch titled net: dsa: make dsa_master_ioctl() see through port_hwtstamp_get() shims to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-dsa-make-dsa_master_ioctl-see-through-port_hwtst.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 83730ebd680280471ccbf9f92bc797a6b130350f Author: Vladimir Oltean <vladimir.oltean@xxxxxxx> Date: Fri Nov 11 23:10:20 2022 +0200 net: dsa: make dsa_master_ioctl() see through port_hwtstamp_get() shims [ Upstream commit ed1fe1bebe18884b11e5536b5ac42e3a48960835 ] There are multi-generational drivers like mv88e6xxx which have code like this: int mv88e6xxx_port_hwtstamp_get(struct dsa_switch *ds, int port, struct ifreq *ifr) { if (!chip->info->ptp_support) return -EOPNOTSUPP; ... } DSA wants to deny PTP timestamping on the master if the switch supports timestamping too. However it currently relies on the presence of the port_hwtstamp_get() callback to determine PTP capability, and this clearly does not work in that case (method is present but returns -EOPNOTSUPP). We should not deny PTP on the DSA master for those switches which truly do not support hardware timestamping. Create a dsa_port_supports_hwtstamp() method which actually probes for support by calling port_hwtstamp_get() and seeing whether that returned -EOPNOTSUPP or not. Fixes: f685e609a301 ("net: dsa: Deny PTP on master if switch supports it") Link: https://patchwork.kernel.org/project/netdevbpf/patch/20221110124345.3901389-1-festevam@xxxxxxxxx/ Reported-by: Fabio Estevam <festevam@xxxxxxxxx> Reported-by: Steffen Bätz <steffen@xxxxxxxxxxxx> Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx> Tested-by: Fabio Estevam <festevam@xxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h index a5c9bc7b66c6..e91265434354 100644 --- a/net/dsa/dsa_priv.h +++ b/net/dsa/dsa_priv.h @@ -198,6 +198,7 @@ static inline struct net_device *dsa_master_find_slave(struct net_device *dev, } /* port.c */ +bool dsa_port_supports_hwtstamp(struct dsa_port *dp, struct ifreq *ifr); void dsa_port_set_tag_protocol(struct dsa_port *cpu_dp, const struct dsa_device_ops *tag_ops); int dsa_port_set_state(struct dsa_port *dp, u8 state, bool do_fast_age); diff --git a/net/dsa/master.c b/net/dsa/master.c index e8e19857621b..69ec510abe83 100644 --- a/net/dsa/master.c +++ b/net/dsa/master.c @@ -204,8 +204,7 @@ static int dsa_master_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) * switch in the tree that is PTP capable. */ list_for_each_entry(dp, &dst->ports, list) - if (dp->ds->ops->port_hwtstamp_get || - dp->ds->ops->port_hwtstamp_set) + if (dsa_port_supports_hwtstamp(dp, ifr)) return -EBUSY; break; } diff --git a/net/dsa/port.c b/net/dsa/port.c index a21015d6bd36..31e8a7a8c3e6 100644 --- a/net/dsa/port.c +++ b/net/dsa/port.c @@ -75,6 +75,22 @@ static bool dsa_port_can_configure_learning(struct dsa_port *dp) return !err; } +bool dsa_port_supports_hwtstamp(struct dsa_port *dp, struct ifreq *ifr) +{ + struct dsa_switch *ds = dp->ds; + int err; + + if (!ds->ops->port_hwtstamp_get || !ds->ops->port_hwtstamp_set) + return false; + + /* "See through" shim implementations of the "get" method. + * This will clobber the ifreq structure, but we will either return an + * error, or the master will overwrite it with proper values. + */ + err = ds->ops->port_hwtstamp_get(ds, dp->index, ifr); + return err != -EOPNOTSUPP; +} + int dsa_port_set_state(struct dsa_port *dp, u8 state, bool do_fast_age) { struct dsa_switch *ds = dp->ds;