linux-kernel - [PATCH 5.17 0510/1126] ptp: unregister virtual clocks when unregistering physical clock.

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Date:   Tue,  5 Apr 2022 09:20:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Miroslav Lichvar <mlichvar@...hat.com>,
        Richard Cochran <richardcochran@...il.com>,
        Yangbo Lu <yangbo.lu@....com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.17 0510/1126] ptp: unregister virtual clocks when unregistering physical clock.

From: Miroslav Lichvar <mlichvar@...hat.com>

[ Upstream commit bfcbb76b0f595ea9ede9f7a218086fef85242f10 ]

When unregistering a physical clock which has some virtual clocks,
unregister the virtual clocks with it.

This fixes the following oops, which can be triggered by unloading
a driver providing a PTP clock when it has enabled virtual clocks:

BUG: unable to handle page fault for address: ffffffffc04fc4d8
Oops: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:ptp_vclock_read+0x31/0xb0
Call Trace:
 timecounter_read+0xf/0x50
 ptp_vclock_refresh+0x2c/0x50
 ? ptp_clock_release+0x40/0x40
 ptp_aux_kworker+0x17/0x30
 kthread_worker_fn+0x9b/0x240
 ? kthread_should_park+0x30/0x30
 kthread+0xe2/0x110
 ? kthread_complete_and_exit+0x20/0x20
 ret_from_fork+0x22/0x30

Fixes: 73f37068d540 ("ptp: support ptp physical/virtual clocks conversion")
Signed-off-by: Miroslav Lichvar <mlichvar@...hat.com>
Acked-by: Richard Cochran <richardcochran@...il.com>
Cc: Yangbo Lu <yangbo.lu@....com>
Cc: Yang Yingliang <yangyingliang@...wei.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/ptp/ptp_clock.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index 0e4bc8b9329d..b6f2cfd15dd2 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -317,11 +317,18 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 }
 EXPORT_SYMBOL(ptp_clock_register);
 
+static int unregister_vclock(struct device *dev, void *data)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+
+	ptp_vclock_unregister(info_to_vclock(ptp->info));
+	return 0;
+}
+
 int ptp_clock_unregister(struct ptp_clock *ptp)
 {
 	if (ptp_vclock_in_use(ptp)) {
-		pr_err("ptp: virtual clock in use\n");
-		return -EBUSY;
+		device_for_each_child(&ptp->dev, NULL, unregister_vclock);
 	}
 
 	ptp->defunct = 1;
-- 
2.34.1