[PATCH net v3 1/2] net: ravb: handle unavailable PTP clock

[xuanqiang.luo@linux.dev]

From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>

The PTP clock is registered by ravb_open(), not ravb_probe(). Therefore,
priv->ptp.clock is NULL between register_netdev() and the first open, and
ethtool -T triggers a NULL dereference in ptp_clock_index().

ptp_clock_register() may also return an error pointer, which can reach
ptp_clock_index() or ptp_clock_unregister().

Normalize registration errors to NULL and only query or unregister the
clock when it is present. Leave phc_index at -1 when no PHC is registered,
while preserving the static hardware timestamping capabilities.

Fixes: a0d2f20650e8 ("Renesas Ethernet AVB PTP clock driver")
Cc: stable@vger.kernel.org
Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
---
 drivers/net/ethernet/renesas/ravb_main.c |  3 ++-
 drivers/net/ethernet/renesas/ravb_ptp.c  | 12 ++++++++++--
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 5f88733094d0f..3a9d9f8718216 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -1779,7 +1779,8 @@ static int ravb_get_ts_info(struct net_device *ndev,
 			(1 << HWTSTAMP_FILTER_NONE) |
 			(1 << HWTSTAMP_FILTER_PTP_V2_L2_EVENT) |
 			(1 << HWTSTAMP_FILTER_ALL);
-		info->phc_index = ptp_clock_index(priv->ptp.clock);
+		if (priv->ptp.clock)
+			info->phc_index = ptp_clock_index(priv->ptp.clock);
 	}
 
 	return 0;
diff --git a/drivers/net/ethernet/renesas/ravb_ptp.c b/drivers/net/ethernet/renesas/ravb_ptp.c
index 226c6c0ab945b..eaf07cb8eadfa 100644
--- a/drivers/net/ethernet/renesas/ravb_ptp.c
+++ b/drivers/net/ethernet/renesas/ravb_ptp.c
@@ -315,6 +315,7 @@ void ravb_ptp_interrupt(struct net_device *ndev)
 void ravb_ptp_init(struct net_device *ndev, struct platform_device *pdev)
 {
 	struct ravb_private *priv = netdev_priv(ndev);
+	struct ptp_clock *clock;
 	unsigned long flags;
 
 	priv->ptp.info = ravb_ptp_info;
@@ -327,7 +328,13 @@ void ravb_ptp_init(struct net_device *ndev, struct platform_device *pdev)
 	ravb_modify(ndev, GCCR, GCCR_TCSS, GCCR_TCSS_ADJGPTP);
 	spin_unlock_irqrestore(&priv->lock, flags);
 
-	priv->ptp.clock = ptp_clock_register(&priv->ptp.info, &pdev->dev);
+	clock = ptp_clock_register(&priv->ptp.info, &pdev->dev);
+	if (IS_ERR(clock)) {
+		netdev_err(ndev, "failed to register PTP clock: %pe\n", clock);
+		clock = NULL;
+	}
+
+	priv->ptp.clock = clock;
 }
 
 void ravb_ptp_stop(struct net_device *ndev)
@@ -337,5 +344,6 @@ void ravb_ptp_stop(struct net_device *ndev)
 	ravb_write(ndev, 0, GIC);
 	ravb_write(ndev, 0, GIS);
 
-	ptp_clock_unregister(priv->ptp.clock);
+	if (priv->ptp.clock)
+		ptp_clock_unregister(priv->ptp.clock);
 }
-- 
2.43.0