net: mscc: ocelot: avoid overflowing the PTP timestamp FIFO

PTP packets with 2-step TX timestamp requests are matched to packets
based on the egress port number and a 6-bit timestamp identifier.
All PTP timestamps are held in a common FIFO that is 128 entry deep.

This patch ensures that back-to-back timestamping requests cannot exceed
the hardware FIFO capacity. If that happens, simply send the packets
without requesting a TX timestamp to be taken (in the case of felix,
since the DSA API has a void return code in ds->ops->port_txtstamp) or
drop them (in the case of ocelot).

I've moved the ts_id_lock from a per-port basis to a per-switch basis,
because we need separate accounting for both numbers of PTP frames in
flight. And since we need locking to inc/dec the per-switch counter,
that also offers protection for the per-port counter and hence there is
no reason to have a per-port counter anymore.

Fixes: 4e3b0468e6d7 ("net: mscc: PTP Hardware Clock (PHC) support")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
index a3a9636..50ef207 100644 (file)
--- a/drivers/net/dsa/ocelot/felix.c
+++ b/drivers/net/dsa/ocelot/felix.c
@@ -1291,8 +1291,12 @@ static void felix_txtstamp(struct dsa_switch *ds, int port,
        if (!ocelot->ptp)
                return;
 
-       if (ocelot_port_txtstamp_request(ocelot, port, skb, &clone))
+       if (ocelot_port_txtstamp_request(ocelot, port, skb, &clone)) {
+               dev_err_ratelimited(ds->dev,
+                                   "port %d delivering skb without TX timestamp\n",
+                                   port);
                return;
+       }
 
        if (clone)
                OCELOT_SKB_CB(skb)->clone = clone;

diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
index c43c8f5..9c62f1d 100644 (file)
--- a/drivers/net/ethernet/mscc/ocelot.c
+++ b/drivers/net/ethernet/mscc/ocelot.c
@@ -569,22 +569,36 @@ void ocelot_phylink_mac_link_up(struct ocelot *ocelot, int port,
 }
 EXPORT_SYMBOL_GPL(ocelot_phylink_mac_link_up);
 
-static void ocelot_port_add_txtstamp_skb(struct ocelot *ocelot, int port,
-                                        struct sk_buff *clone)
+static int ocelot_port_add_txtstamp_skb(struct ocelot *ocelot, int port,
+                                       struct sk_buff *clone)
 {
        struct ocelot_port *ocelot_port = ocelot->ports[port];
+       unsigned long flags;
+
+       spin_lock_irqsave(&ocelot->ts_id_lock, flags);
 
-       spin_lock(&ocelot_port->ts_id_lock);
+       if (ocelot_port->ptp_skbs_in_flight == OCELOT_MAX_PTP_ID ||
+           ocelot->ptp_skbs_in_flight == OCELOT_PTP_FIFO_SIZE) {
+               spin_unlock_irqrestore(&ocelot->ts_id_lock, flags);
+               return -EBUSY;
+       }
 
        skb_shinfo(clone)->tx_flags |= SKBTX_IN_PROGRESS;
        /* Store timestamp ID in OCELOT_SKB_CB(clone)->ts_id */
        OCELOT_SKB_CB(clone)->ts_id = ocelot_port->ts_id;
+
        ocelot_port->ts_id++;
        if (ocelot_port->ts_id == OCELOT_MAX_PTP_ID)
                ocelot_port->ts_id = 0;
+
+       ocelot_port->ptp_skbs_in_flight++;
+       ocelot->ptp_skbs_in_flight++;
+
        skb_queue_tail(&ocelot_port->tx_skbs, clone);
 
-       spin_unlock(&ocelot_port->ts_id_lock);
+       spin_unlock_irqrestore(&ocelot->ts_id_lock, flags);
+
+       return 0;
 }
 
 u32 ocelot_ptp_rew_op(struct sk_buff *skb)
@@ -633,6 +647,7 @@ int ocelot_port_txtstamp_request(struct ocelot *ocelot, int port,
 {
        struct ocelot_port *ocelot_port = ocelot->ports[port];
        u8 ptp_cmd = ocelot_port->ptp_cmd;
+       int err;
 
        /* Store ptp_cmd in OCELOT_SKB_CB(skb)->ptp_cmd */
        if (ptp_cmd == IFH_REW_OP_ORIGIN_PTP) {
@@ -650,7 +665,10 @@ int ocelot_port_txtstamp_request(struct ocelot *ocelot, int port,
                if (!(*clone))
                        return -ENOMEM;
 
-               ocelot_port_add_txtstamp_skb(ocelot, port, *clone);
+               err = ocelot_port_add_txtstamp_skb(ocelot, port, *clone);
+               if (err)
+                       return err;
+
                OCELOT_SKB_CB(skb)->ptp_cmd = ptp_cmd;
        }
 
@@ -709,9 +727,14 @@ void ocelot_get_txtstamp(struct ocelot *ocelot)
                id = SYS_PTP_STATUS_PTP_MESS_ID_X(val);
                txport = SYS_PTP_STATUS_PTP_MESS_TXPORT_X(val);
 
-               /* Retrieve its associated skb */
                port = ocelot->ports[txport];
 
+               spin_lock(&ocelot->ts_id_lock);
+               port->ptp_skbs_in_flight--;
+               ocelot->ptp_skbs_in_flight--;
+               spin_unlock(&ocelot->ts_id_lock);
+
+               /* Retrieve its associated skb */
                spin_lock_irqsave(&port->tx_skbs.lock, flags);
 
                skb_queue_walk_safe(&port->tx_skbs, skb, skb_tmp) {
@@ -1950,7 +1973,6 @@ 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 */
 
@@ -2083,6 +2105,7 @@ int ocelot_init(struct ocelot *ocelot)
        mutex_init(&ocelot->stats_lock);
        mutex_init(&ocelot->ptp_lock);
        spin_lock_init(&ocelot->ptp_clock_lock);
+       spin_lock_init(&ocelot->ts_id_lock);
        snprintf(queue_name, sizeof(queue_name), "%s-stats",
                 dev_name(ocelot->dev));
        ocelot->stats_queue = create_singlethread_workqueue(queue_name);

diff --git a/include/soc/mscc/ocelot.h b/include/soc/mscc/ocelot.h
index 06706a9..b0ece85 100644 (file)
--- a/include/soc/mscc/ocelot.h
+++ b/include/soc/mscc/ocelot.h
@@ -603,10 +603,10 @@ struct ocelot_port {
        /* The VLAN ID that will be transmitted as untagged, on egress */
        struct ocelot_vlan              native_vlan;
 
+       unsigned int                    ptp_skbs_in_flight;
        u8                              ptp_cmd;
        struct sk_buff_head             tx_skbs;
        u8                              ts_id;
-       spinlock_t                      ts_id_lock;
 
        phy_interface_t                 phy_mode;
 
@@ -680,6 +680,9 @@ struct ocelot {
        struct ptp_clock                *ptp_clock;
        struct ptp_clock_info           ptp_info;
        struct hwtstamp_config          hwtstamp_config;
+       unsigned int                    ptp_skbs_in_flight;
+       /* Protects the 2-step TX timestamp ID logic */
+       spinlock_t                      ts_id_lock;
        /* Protects the PTP interface state */
        struct mutex                    ptp_lock;
        /* Protects the PTP clock */

diff --git a/include/soc/mscc/ocelot_ptp.h b/include/soc/mscc/ocelot_ptp.h
index 6e54442..f085884 100644 (file)
--- a/include/soc/mscc/ocelot_ptp.h
+++ b/include/soc/mscc/ocelot_ptp.h
@@ -14,6 +14,7 @@
 #include <soc/mscc/ocelot.h>
 
 #define OCELOT_MAX_PTP_ID              63
+#define OCELOT_PTP_FIFO_SIZE           128
 
 #define PTP_PIN_CFG_RSZ                        0x20
 #define PTP_PIN_TOD_SEC_MSB_RSZ                PTP_PIN_CFG_RSZ