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 --- net/dsa/tag_ocelot.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'net/dsa') diff --git a/net/dsa/tag_ocelot.c b/net/dsa/tag_ocelot.c index 42f327c06dca..b4fc05cafaa6 100644 --- a/net/dsa/tag_ocelot.c +++ b/net/dsa/tag_ocelot.c @@ -160,11 +160,14 @@ static struct sk_buff *ocelot_xmit(struct sk_buff *skb, packing(injection, &qos_class, 19, 17, OCELOT_TAG_LEN, PACK, 0); if (ocelot->ptp && (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) { + struct sk_buff *clone = DSA_SKB_CB(skb)->clone; + rew_op = ocelot_port->ptp_cmd; - if (ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) { - rew_op |= (ocelot_port->ts_id % 4) << 3; - ocelot_port->ts_id++; - } + /* Retrieve timestamp ID populated inside skb->cb[0] of the + * clone by ocelot_port_add_txtstamp_skb + */ + if (ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) + rew_op |= clone->cb[0] << 3; packing(injection, &rew_op, 125, 117, OCELOT_TAG_LEN, PACK, 0); } -- cgit