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net: dsa: make dsa_master_ioctl() see through port_hwtstamp_get() shims

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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: f685e609a3 ("net: dsa: Deny PTP on master if switch supports it")
Link: https://patchwork.kernel.org/project/netdevbpf/patch/20221110124345.3901389-1-festevam@gmail.com/
Reported-by: Fabio Estevam <festevam@gmail.com>
Reported-by: Steffen Bätz <steffen@innosonix.de>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vladimir Oltean 2022-11-11 23:10:20 +02:00 committed by David S. Miller
parent f7c125bd79
commit ed1fe1bebe
3 changed files with 18 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
net/dsa/dsa_priv.h
View File

@ -210,6 +210,7 @@ static inline struct net_device *dsa_master_find_slave(struct net_device *dev,
extern struct rtnl_link_ops dsa_link_ops __read_mostly;
/* 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);

3
net/dsa/master.c
View File

@ -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;
}

16
net/dsa/port.c
View File

@ -110,6 +110,22 @@ 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;