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authorVladimir Oltean <vladimir.oltean@nxp.com>2020-09-18 04:07:24 +0300
committerDavid S. Miller <davem@davemloft.net>2020-09-18 23:52:33 +0300
commit6565243c0677aa2befa5a953cf11bc7b4a6f0a47 (patch)
tree2b57ec438bfe55b8e25f47f4a7df5e7aae959545 /net
parent9dda66acddcbcd5c9e94a1292c679738ba999345 (diff)
downloadlinux-6565243c0677aa2befa5a953cf11bc7b4a6f0a47.tar.xz
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>
Diffstat (limited to 'net')
-rw-r--r--net/dsa/tag_ocelot.c11
1 files changed, 7 insertions, 4 deletions
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);
}