net: mscc: ocelot: add locking for the port TX timestamp ID
The ocelot_port->ts_id is used to:
(a) populate skb->cb[0] for matching the TX timestamp in the PTP IRQ
with an skb.
(b) populate the REW_OP from the injection header of the ongoing skb.
Only then is ocelot_port->ts_id incremented.
This is a problem because, at least theoretically, another timestampable
skb might use the same ocelot_port->ts_id before that is incremented.
Normally all transmit calls are serialized by the netdev transmit
spinlock, but in this case, ocelot_port_add_txtstamp_skb() is also
called by DSA, which has started declaring the NETIF_F_LLTX feature
since commit 2b86cb829976 ("net: dsa: declare lockless TX feature for
slave ports"). So the logic of using and incrementing the timestamp id
should be atomic per port.
The solution is to use the global ocelot_port->ts_id only while
protected by the associated ocelot_port->ts_id_lock. That's where we
populate skb->cb[0]. Note that for ocelot, ocelot_port_add_txtstamp_skb
is called for the actual skb, but for felix, it is called for the skb's
clone. That is something which will also be changed in the future.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
index 5abb7d2..83eb7c3 100644
--- a/drivers/net/ethernet/mscc/ocelot.c
+++ b/drivers/net/ethernet/mscc/ocelot.c
@@ -421,10 +421,15 @@ int ocelot_port_add_txtstamp_skb(struct ocelot_port *ocelot_port,
if (ocelot->ptp && shinfo->tx_flags & SKBTX_HW_TSTAMP &&
ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) {
+ spin_lock(&ocelot_port->ts_id_lock);
+
shinfo->tx_flags |= SKBTX_IN_PROGRESS;
/* Store timestamp ID in cb[0] of sk_buff */
- skb->cb[0] = ocelot_port->ts_id % 4;
+ skb->cb[0] = ocelot_port->ts_id;
+ ocelot_port->ts_id = (ocelot_port->ts_id + 1) % 4;
skb_queue_tail(&ocelot_port->tx_skbs, skb);
+
+ spin_unlock(&ocelot_port->ts_id_lock);
return 0;
}
return -ENODATA;
@@ -1300,6 +1305,7 @@ void ocelot_init_port(struct ocelot *ocelot, int port)
struct ocelot_port *ocelot_port = ocelot->ports[port];
skb_queue_head_init(&ocelot_port->tx_skbs);
+ spin_lock_init(&ocelot_port->ts_id_lock);
/* Basic L2 initialization */