Commit 3ff468ef authored by Vladimir Oltean's avatar Vladimir Oltean Committed by Jakub Kicinski
Browse files

net: mscc: ocelot: remove struct ocelot_mm_state :: lock 



Unfortunately, the workarounds for the hardware bugs make it pointless
to keep fine-grained locking for the MAC Merge state of each port.

Our vsc9959_cut_through_fwd() implementation requires
ocelot->fwd_domain_lock to be held, in order to serialize with changes
to the bridging domains and to port speed changes (which affect which
ports can be cut-through). Simultaneously, the traffic classes which can
be cut-through cannot be preemptible at the same time, and this will
depend on the MAC Merge layer state (which changes from threaded
interrupt context).

Since vsc9959_cut_through_fwd() would have to hold the mm->lock of all
ports for a correct and race-free implementation with respect to
ocelot_mm_irq(), in practice it means that any time a port's mm->lock is
held, it would potentially block holders of ocelot->fwd_domain_lock.

In the interest of simple locking rules, make all MAC Merge layer state
changes (and preemptible traffic class changes) be serialized by the
ocelot->fwd_domain_lock.

Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: default avatarSimon Horman <simon.horman@corigine.com>
Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 15f93f46

drivers/net/ethernet/mscc/ocelot_mm.c

+8 −12
Original line number Diff line number Diff line
@@ -56,8 +56,6 @@ static void ocelot_mm_update_port_status(struct ocelot *ocelot, int port) 
	enum ethtool_mm_verify_status verify_status;

	u32 val;



	mutex_lock(&mm->lock);



	val = ocelot_port_readl(ocelot_port, DEV_MM_STATUS);



	verify_status = ocelot_mm_verify_status(val);
@@ -88,16 +86,18 @@ static void ocelot_mm_update_port_status(struct ocelot *ocelot, int port) 
	}



	ocelot_port_writel(ocelot_port, val, DEV_MM_STATUS);



	mutex_unlock(&mm->lock);

}



void ocelot_mm_irq(struct ocelot *ocelot)

{

	int port;



	mutex_lock(&ocelot->fwd_domain_lock);



	for (port = 0; port < ocelot->num_phys_ports; port++)

		ocelot_mm_update_port_status(ocelot, port);



	mutex_unlock(&ocelot->fwd_domain_lock);

}

EXPORT_SYMBOL_GPL(ocelot_mm_irq);
@@ -107,14 +107,11 @@ int ocelot_port_set_mm(struct ocelot *ocelot, int port, 
{

	struct ocelot_port *ocelot_port = ocelot->ports[port];

	u32 mm_enable = 0, verify_disable = 0, add_frag_size;

	struct ocelot_mm_state *mm;

	int err;



	if (!ocelot->mm_supported)

		return -EOPNOTSUPP;



	mm = &ocelot->mm[port];



	err = ethtool_mm_frag_size_min_to_add(cfg->tx_min_frag_size,

					      &add_frag_size, extack);

	if (err)
@@ -129,7 +126,7 @@ int ocelot_port_set_mm(struct ocelot *ocelot, int port, 
	if (!cfg->verify_enabled)

		verify_disable = DEV_MM_CONFIG_VERIF_CONFIG_PRM_VERIFY_DIS;



	mutex_lock(&mm->lock);

	mutex_lock(&ocelot->fwd_domain_lock);



	ocelot_port_rmwl(ocelot_port, mm_enable,

			 DEV_MM_CONFIG_ENABLE_CONFIG_MM_TX_ENA |
@@ -148,7 +145,7 @@ int ocelot_port_set_mm(struct ocelot *ocelot, int port, 
		       QSYS_PREEMPTION_CFG,

		       port);



	mutex_unlock(&mm->lock);

	mutex_unlock(&ocelot->fwd_domain_lock);



	return 0;

}
@@ -166,7 +163,7 @@ int ocelot_port_get_mm(struct ocelot *ocelot, int port, 


	mm = &ocelot->mm[port];



	mutex_lock(&mm->lock);

	mutex_lock(&ocelot->fwd_domain_lock);



	val = ocelot_port_readl(ocelot_port, DEV_MM_ENABLE_CONFIG);

	state->pmac_enabled = !!(val & DEV_MM_CONFIG_ENABLE_CONFIG_MM_RX_ENA);
@@ -185,7 +182,7 @@ int ocelot_port_get_mm(struct ocelot *ocelot, int port, 
	state->verify_status = mm->verify_status;

	state->tx_active = mm->tx_active;



	mutex_unlock(&mm->lock);

	mutex_unlock(&ocelot->fwd_domain_lock);



	return 0;

}
@@ -209,7 +206,6 @@ int ocelot_mm_init(struct ocelot *ocelot) 
		u32 val;



		mm = &ocelot->mm[port];

		mutex_init(&mm->lock);

		ocelot_port = ocelot->ports[port];



		/* Update initial status variable for the

include/soc/mscc/ocelot.h

+0 −1
Original line number Diff line number Diff line
@@ -744,7 +744,6 @@ struct ocelot_mirror { 
};



struct ocelot_mm_state {

	struct mutex lock;

	enum ethtool_mm_verify_status verify_status;

	bool tx_active;

};