net: mscc: ocelot: serialize access to the injection/extraction groups

As explained by Horatiu Vultur in commit 603ead96582d ("net: sparx5: Add
spinlock for frame transmission from CPU") which is for a similar
hardware design, multiple CPUs can simultaneously perform injection
or extraction. There are only 2 register groups for injection and 2
for extraction, and the driver only uses one of each. So we'd better
serialize access using spin locks, otherwise frame corruption is
possible.

Note that unlike in sparx5, FDMA in ocelot does not have this issue
because struct ocelot_fdma_tx_ring already contains an xmit_lock.

I guess this is mostly a problem for NXP LS1028A, as that is dual core.
I don't think VSC7514 is. So I'm blaming the commit where LS1028A (aka
the felix DSA driver) started using register-based packet injection and
extraction.

Fixes: 0a6f17c6ae21 ("net: dsa: tag_ocelot_8021q: add support for PTP timestamping")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
index e554699f06d4..8d31ff18c5c7 100644
--- a/drivers/net/dsa/ocelot/felix.c
+++ b/drivers/net/dsa/ocelot/felix.c
@@ -528,7 +528,9 @@ static int felix_tag_8021q_setup(struct dsa_switch *ds)
 	 * so we need to be careful that there are no extra frames to be
 	 * dequeued over MMIO, since we would never know to discard them.
 	 */
+	ocelot_lock_xtr_grp_bh(ocelot, 0);
 	ocelot_drain_cpu_queue(ocelot, 0);
+	ocelot_unlock_xtr_grp_bh(ocelot, 0);
 
 	return 0;
 }
@@ -1518,6 +1520,8 @@ static void felix_port_deferred_xmit(struct kthread_work *work)
 	int port = xmit_work->dp->index;
 	int retries = 10;
 
+	ocelot_lock_inj_grp(ocelot, 0);
+
 	do {
 		if (ocelot_can_inject(ocelot, 0))
 			break;
@@ -1526,6 +1530,7 @@ static void felix_port_deferred_xmit(struct kthread_work *work)
 	} while (--retries);
 
 	if (!retries) {
+		ocelot_unlock_inj_grp(ocelot, 0);
 		dev_err(ocelot->dev, "port %d failed to inject skb\n",
 			port);
 		ocelot_port_purge_txtstamp_skb(ocelot, port, skb);
@@ -1535,6 +1540,8 @@ static void felix_port_deferred_xmit(struct kthread_work *work)
 
 	ocelot_port_inject_frame(ocelot, port, 0, rew_op, skb);
 
+	ocelot_unlock_inj_grp(ocelot, 0);
+
 	consume_skb(skb);
 	kfree(xmit_work);
 }
@@ -1694,6 +1701,8 @@ static bool felix_check_xtr_pkt(struct ocelot *ocelot)
 	if (!felix->info->quirk_no_xtr_irq)
 		return false;
 
+	ocelot_lock_xtr_grp(ocelot, grp);
+
 	while (ocelot_read(ocelot, QS_XTR_DATA_PRESENT) & BIT(grp)) {
 		struct sk_buff *skb;
 		unsigned int type;
@@ -1730,6 +1739,8 @@ out:
 		ocelot_drain_cpu_queue(ocelot, 0);
 	}
 
+	ocelot_unlock_xtr_grp(ocelot, grp);
+
 	return true;
 }