[PATCH net-next v2] ptp: Return -EINVAL on ptp_clock_register if required ops are NULL

[Tim Hostetler <thostet@google.com>]

ptp_clock should never be registered unless it stubs one of gettimex64()
or gettime64() and settime64(). WARN_ON_ONCE and error out if either set
of function pointers is null.

For consistency, n_alarm validation is also folded into the
WARN_ON_ONCE.

Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Tim Hostetler <thostet@google.com>
---
Changes in v2:
  * Switch to net-next tree (Jakub Kicinski, Vadim Fedorenko)
  * Fold in n_alarm check into WARN_ON_ONCE (Jakub Kicinski)
---
 drivers/ptp/ptp_clock.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index ef020599b771..b0e167c0b3eb 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -322,7 +322,9 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 	char debugfsname[16];
 	size_t size;
 
-	if (info->n_alarm > PTP_MAX_ALARMS)
+	if (WARN_ON_ONCE(info->n_alarm > PTP_MAX_ALARMS ||
+			 (!info->gettimex64 && !info->gettime64) ||
+			 !info->settime64))
 		return ERR_PTR(-EINVAL);
 
 	/* Initialize a clock structure. */
-- 
2.51.2.1026.g39e6a42477-goog