Revert "net: dsa: mv88e6xxx: flush switchdev FDB workqueue before rem…

…oving VLAN"

This reverts commit 2566a89 which is
commit a261414 upstream.

The above change depends on upstream commit 0faf890 ("net: dsa:
drop rtnl_lock from dsa_slave_switchdev_event_work"), which is not
present in linux-5.15.y. Without that change, waiting for the switchdev
workqueue causes deadlocks on the rtnl_mutex.

Backporting the dependency commit isn't trivial/desirable, since it
requires that the following dependencies of the dependency are also
backported:

df40591 net: dsa: sja1105: wait for dynamic config command completion on writes too
eb016af net: dsa: sja1105: serialize access to the dynamic config interface
2468346 net: mscc: ocelot: serialize access to the MAC table
f7eb4a1 net: dsa: b53: serialize access to the ARL table
cf231b4 net: dsa: lantiq_gswip: serialize access to the PCE registers
338a3a4 net: dsa: introduce locking for the address lists on CPU and DSA ports

and then this bugfix on top:

8940e6b ("net: dsa: avoid call to __dev_set_promiscuity() while rtnl_mutex isn't held")

Reported-by: Daniel Suchy <danny@danysek.cz>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -2291,13 +2291,6 @@ static int mv88e6xxx_port_vlan_del(struct dsa_switch *ds, int port,
 	if (!mv88e6xxx_max_vid(chip))
 		return -EOPNOTSUPP;
 
-	/* The ATU removal procedure needs the FID to be mapped in the VTU,
-	 * but FDB deletion runs concurrently with VLAN deletion. Flush the DSA
-	 * switchdev workqueue to ensure that all FDB entries are deleted
-	 * before we remove the VLAN.
-	 */
-	dsa_flush_workqueue();
-
 	mv88e6xxx_reg_lock(chip);
 
 	err = mv88e6xxx_port_get_pvid(chip, port, &pvid);

include/net/dsa.h

@@ -1056,7 +1056,6 @@ void dsa_unregister_switch(struct dsa_switch *ds);
 int dsa_register_switch(struct dsa_switch *ds);
 void dsa_switch_shutdown(struct dsa_switch *ds);
 struct dsa_switch *dsa_switch_find(int tree_index, int sw_index);
-void dsa_flush_workqueue(void);
 #ifdef CONFIG_PM_SLEEP
 int dsa_switch_suspend(struct dsa_switch *ds);
 int dsa_switch_resume(struct dsa_switch *ds);

net/dsa/dsa.c

@@ -349,7 +349,6 @@ void dsa_flush_workqueue(void)
 {
 	flush_workqueue(dsa_owq);
 }
-EXPORT_SYMBOL_GPL(dsa_flush_workqueue);
 
 int dsa_devlink_param_get(struct devlink *dl, u32 id,
 			  struct devlink_param_gset_ctx *ctx)

net/dsa/dsa_priv.h

@@ -170,6 +170,7 @@ void dsa_tag_driver_put(const struct dsa_device_ops *ops);
 const struct dsa_device_ops *dsa_find_tagger_by_name(const char *buf);
 
 bool dsa_schedule_work(struct work_struct *work);
+void dsa_flush_workqueue(void);
 const char *dsa_tag_protocol_to_str(const struct dsa_device_ops *ops);
 
 static inline int dsa_tag_protocol_overhead(const struct dsa_device_ops *ops)