From 6565243c0677aa2befa5a953cf11bc7b4a6f0a47 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Fri, 18 Sep 2020 04:07:24 +0300 Subject: 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 Reviewed-by: Horatiu Vultur Reviewed-by: Florian Fainelli Tested-by: Alexandre Belloni Reviewed-by: Alexandre Belloni Signed-off-by: David S. Miller --- drivers/net/ethernet/mscc/ocelot.c | 8 +++++++- drivers/net/ethernet/mscc/ocelot_net.c | 6 ++---- 2 files changed, 9 insertions(+), 5 deletions(-) (limited to 'drivers/net') diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c index 5abb7d2b0a9e..83eb7c325061 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 */ diff --git a/drivers/net/ethernet/mscc/ocelot_net.c b/drivers/net/ethernet/mscc/ocelot_net.c index cacabc23215a..8490e42e9e2d 100644 --- a/drivers/net/ethernet/mscc/ocelot_net.c +++ b/drivers/net/ethernet/mscc/ocelot_net.c @@ -349,10 +349,8 @@ static int ocelot_port_xmit(struct sk_buff *skb, struct net_device *dev) if (ocelot->ptp && shinfo->tx_flags & SKBTX_HW_TSTAMP) { info.rew_op = ocelot_port->ptp_cmd; - if (ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) { - info.rew_op |= (ocelot_port->ts_id % 4) << 3; - ocelot_port->ts_id++; - } + if (ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) + info.rew_op |= skb->cb[0] << 3; } ocelot_gen_ifh(ifh, &info); -- cgit v1.2.3