[PATCH net v2] ptp: fc3: register PTP clock after initialization

[PATCH net v2] ptp: fc3: register PTP clock after initialization

[Myeonghun Pak]

ptp_clock_register() exposes the clock to userspace. If either following
initialization operation fails, probe returns and devres frees idtfc3 while
the registered clock still refers to the clock information embedded in it.

Complete the fallible initialization before registering the clock. Schedule
the worker after registration because it requires the registered clock.
This removes post-registration failures and avoids exposing a partially
initialized clock.

Fixes: 1ddfecafabf7 ("ptp: add FemtoClock3 Wireless as ptp hardware clock")
Cc: stable@vger.kernel.org
Co-developed-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
---
Changes in v2:
- Register the PTP clock after initialization instead of unregistering it
  while holding idtfc3->lock, which could deadlock with a concurrent clock
  operation holding the POSIX clock rwsem.

 drivers/ptp/ptp_fc3.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/ptp/ptp_fc3.c b/drivers/ptp/ptp_fc3.c
index f0e0004..02b9739 100644
--- a/drivers/ptp/ptp_fc3.c
+++ b/drivers/ptp/ptp_fc3.c
@@ -665,8 +665,6 @@ static int idtfc3_init_timecounter(struct idtfc3 *idtfc3)
 	if (err)
 		return err;
 
-	ptp_schedule_worker(idtfc3->ptp_clock, idtfc3->tc_update_period);
-
 	return 0;
 }
 
@@ -825,6 +823,14 @@ static int idtfc3_enable_ptp(struct idtfc3 *idtfc3)
 
 	idtfc3->caps = idtfc3_caps;
 	snprintf(idtfc3->caps.name, sizeof(idtfc3->caps.name), "IDT FC3W");
+	err = idtfc3_set_overhead(idtfc3);
+	if (err)
+		return err;
+
+	err = idtfc3_init_timecounter(idtfc3);
+	if (err)
+		return err;
+
 	idtfc3->ptp_clock = ptp_clock_register(&idtfc3->caps, NULL);
 
 	if (IS_ERR(idtfc3->ptp_clock)) {
@@ -833,13 +839,7 @@ static int idtfc3_enable_ptp(struct idtfc3 *idtfc3)
 		return err;
 	}
 
-	err = idtfc3_set_overhead(idtfc3);
-	if (err)
-		return err;
-
-	err = idtfc3_init_timecounter(idtfc3);
-	if (err)
-		return err;
+	ptp_schedule_worker(idtfc3->ptp_clock, idtfc3->tc_update_period);
 
 	dev_info(idtfc3->dev, "TIME_SYNC_CHANNEL registered as ptp%d",
 		 idtfc3->ptp_clock->index);
-- 
2.50.1