[PATCH net 2/2] net: fec: free the PPS interrupt before tearing down the PHC and netdev

[Shengzhuo Wei]

The dedicated PPS interrupt is devm-managed, so its handler remains
registered until device-managed resources are released after the remove
callback returns.  It therefore outlives both fec_ptp_stop() and
free_netdev().

A handler already in flight can observe pps_enable before fec_ptp_stop()
clears it and call ptp_clock_event() concurrently with
ptp_clock_unregister().  A handler invoked after free_netdev() but before
device-managed cleanup dereferences the freed netdev.

Record the IRQ after a successful request and release it explicitly in
fec_ptp_stop(), before unregistering the PHC.  devm_free_irq() removes the
handler and waits for any running instance, so none can still execute when
PHC teardown begins.  The IRQ is requested without IRQF_SHARED, so its
release does not affect another handler.

Fixes: 4ad1ceec05e4 ("net: fec: Let fec_ptp have its own interrupt routine")
Cc: stable@xxxxxxxxxxxxxxx
Assisted-by: GLM:5.3
Signed-off-by: Shengzhuo Wei <me@xxxxxxxx>
---
 drivers/net/ethernet/freescale/fec.h     |  1 +
 drivers/net/ethernet/freescale/fec_ptp.c | 11 ++++++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index 7176803146f3..960b9f01c531 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -670,6 +670,7 @@ struct fec_enet_private {
 
 	/* pps  */
 	int pps_channel;
+	int pps_irq;
 	unsigned int reload_period;
 	int pps_enable;
 	unsigned int next_counter;
diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
index 0036549974fd..5b1d58c85fcd 100644
--- a/drivers/net/ethernet/freescale/fec_ptp.c
+++ b/drivers/net/ethernet/freescale/fec_ptp.c
@@ -787,9 +787,12 @@ void fec_ptp_init(struct platform_device *pdev, int irq_idx)
 	if (irq >= 0) {
 		ret = devm_request_irq(&pdev->dev, irq, fec_pps_interrupt,
 				       0, pdev->name, ndev);
-		if (ret < 0)
+		if (ret < 0) {
 			dev_warn(&pdev->dev, "request for pps irq failed(%d)\n",
 				 ret);
+		} else {
+			fep->pps_irq = irq;
+		}
 	}
 
 	fep->ptp_clock = ptp_clock_register(&fep->ptp_caps, &pdev->dev);
@@ -861,6 +864,12 @@ void fec_ptp_stop(struct platform_device *pdev)
 
 	cancel_delayed_work_sync(&fep->time_keep);
 	hrtimer_cancel(&fep->perout_timer);
+
+	if (fep->pps_irq > 0) {
+		devm_free_irq(&pdev->dev, fep->pps_irq, ndev);
+		fep->pps_irq = 0;
+	}
+
 	if (fep->ptp_clock) {
 		ptp_clock_unregister(fep->ptp_clock);
 		fep->ptp_clock = NULL;

-- 
2.47.3