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net: mscc: ocelot: ocelot->ts_id_lock and ocelot_port->tx_skbs.lock are IRQ-safe

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ocelot_get_txtstamp() is a threaded IRQ handler, requested explicitly as
such by both ocelot_ptp_rdy_irq_handler() and vsc9959_irq_handler().

As such, it runs with IRQs enabled, and not in hardirq context. Thus,
ocelot_port_add_txtstamp_skb() has no reason to turn off IRQs, it cannot
be preempted by ocelot_get_txtstamp(). For the same reason,
dev_kfree_skb_any_reason() will always evaluate as kfree_skb_reason() in
this calling context, so just simplify the dev_kfree_skb_any() call to
kfree_skb().

Also, ocelot_port_txtstamp_request() runs from NET_TX softirq context,
not with hardirqs enabled. Thus, ocelot_get_txtstamp() which shares the
ocelot_port->tx_skbs.lock lock with it, has no reason to disable hardirqs.

This is part of a larger rework of the TX timestamping procedure.
A logical subportion of the rework has been split into a separate
change.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241205145519.1236778-4-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Vladimir Oltean 2024-12-05 16:55:17 +02:00 committed by Jakub Kicinski
parent b6fba4b3f0
commit 0c53cdb95e
1 changed files with 6 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

14
drivers/net/ethernet/mscc/ocelot_ptp.c
View file

@ -607,13 +607,12 @@ 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->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);
spin_unlock(&ocelot->ts_id_lock);
return -EBUSY;
}
@ -630,7 +629,7 @@ static int ocelot_port_add_txtstamp_skb(struct ocelot *ocelot, int port,
skb_queue_tail(&ocelot_port->tx_skbs, clone);
spin_unlock_irqrestore(&ocelot->ts_id_lock, flags);
spin_unlock(&ocelot->ts_id_lock);
return 0;
}
@ -749,7 +748,6 @@ void ocelot_get_txtstamp(struct ocelot *ocelot)
u32 val, id, seqid, txport;
struct ocelot_port *port;
struct timespec64 ts;
unsigned long flags;
val = ocelot_read(ocelot, SYS_PTP_STATUS);
@ -773,7 +771,7 @@ void ocelot_get_txtstamp(struct ocelot *ocelot)
/* Retrieve its associated skb */
try_again:
spin_lock_irqsave(&port->tx_skbs.lock, flags);
spin_lock(&port->tx_skbs.lock);
skb_queue_walk_safe(&port->tx_skbs, skb, skb_tmp) {
if (OCELOT_SKB_CB(skb)->ts_id != id)
@ -783,7 +781,7 @@ void ocelot_get_txtstamp(struct ocelot *ocelot)
break;
}
spin_unlock_irqrestore(&port->tx_skbs.lock, flags);
spin_unlock(&port->tx_skbs.lock);
if (WARN_ON(!skb_match))
goto next_ts;
@ -792,7 +790,7 @@ void ocelot_get_txtstamp(struct ocelot *ocelot)
dev_err_ratelimited(ocelot->dev,
"port %d received stale TX timestamp for seqid %d, discarding\n",
txport, seqid);
dev_kfree_skb_any(skb);
kfree_skb(skb);
goto try_again;
}