netdev - [PATCH v2] ptp: free ptp clock properly

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Message-ID: <20200309172238.GJ267906@xps-13>
Date:   Mon, 9 Mar 2020 18:22:38 +0100
From:   Andrea Righi <andrea.righi@...onical.com>
To:     Richard Cochran <richardcochran@...il.com>,
        Vladis Dronov <vdronov@...hat.com>
Cc:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] ptp: free ptp clock properly

There is a bug in ptp_clock_unregister() where pps_unregister_source()
can free up resources needed by posix_clock_unregister() to properly
destroy a related sysfs device.

Fix this by calling pps_unregister_source() in ptp_clock_release().

See also:
commit 75718584cb3c ("ptp: free ptp device pin descriptors properly").

BugLink: https://bugs.launchpad.net/bugs/1864754
Fixes: a33121e5487b ("ptp: fix the race between the release of ptp_clock and cdev")
Tested-by: Piotr Morgwai Kotarbiński <foss@...gwai.pl>
Signed-off-by: Andrea Righi <andrea.righi@...onical.com>
---

v2: move pps_unregister_source() to ptp_clock_release(), instead of
    posix_clock_unregister(), that would just introduce a resource leak

 drivers/ptp/ptp_clock.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index ac1f2bf9e888..468286ef61ad 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -170,6 +170,9 @@ static void ptp_clock_release(struct device *dev)
 {
 	struct ptp_clock *ptp = container_of(dev, struct ptp_clock, dev);
 
+	/* Release the clock's resources. */
+	if (ptp->pps_source)
+		pps_unregister_source(ptp->pps_source);
 	ptp_cleanup_pin_groups(ptp);
 	mutex_destroy(&ptp->tsevq_mux);
 	mutex_destroy(&ptp->pincfg_mux);
@@ -298,11 +301,6 @@ int ptp_clock_unregister(struct ptp_clock *ptp)
 		kthread_cancel_delayed_work_sync(&ptp->aux_work);
 		kthread_destroy_worker(ptp->kworker);
 	}
-
-	/* Release the clock's resources. */
-	if (ptp->pps_source)
-		pps_unregister_source(ptp->pps_source);
-
 	posix_clock_unregister(&ptp->clock);
 
 	return 0;
-- 
2.25.0