igc: return an error if the mac type is unknown in igc_ptp_systim_to_hwtstamp()

stable inclusion
from stable-v5.10.168
commit 6362b861704fbf7d331bba35407927d9cd84eb9b
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7URR4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6362b861704fbf7d331bba35407927d9cd84eb9b

----------------------------------------------------

[ Upstream commit a2df8463 ]

clang static analysis reports
drivers/net/ethernet/intel/igc/igc_ptp.c:673:3: warning: The left operand of
  '+' is a garbage value [core.UndefinedBinaryOperatorResult]
   ktime_add_ns(shhwtstamps.hwtstamp, adjust);
   ^            ~~~~~~~~~~~~~~~~~~~~

igc_ptp_systim_to_hwtstamp() silently returns without setting the hwtstamp
if the mac type is unknown.  This should be treated as an error.

Fixes: 81b05520 ("igc: Add support for RX timestamping")
Signed-off-by: NTom Rix <trix@redhat.com>
Reviewed-by: NSimon Horman <simon.horman@corigine.com>
Acked-by: NSasha Neftin <sasha.neftin@intel.com>
Tested-by: NNaama Meir <naamax.meir@linux.intel.com>
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Link: https://lore.kernel.org/r/20230131215437.1528994-1-anthony.l.nguyen@intel.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nzhaoxiaoqiang11 <zhaoxiaoqiang11@jd.com>

drivers/net/ethernet/intel/igc/igc_ptp.c

@@ -134,8 +134,10 @@ static int igc_ptp_feature_enable_i225(struct ptp_clock_info *ptp,
  *
  * We need to convert the system time value stored in the RX/TXSTMP registers
  * into a hwtstamp which can be used by the upper level timestamping functions.
+ *
+ * Returns 0 on success.
  **/
-static void igc_ptp_systim_to_hwtstamp(struct igc_adapter *adapter,
+static int igc_ptp_systim_to_hwtstamp(struct igc_adapter *adapter,
 				      struct skb_shared_hwtstamps *hwtstamps,
 				      u64 systim)
 {
@@ -147,8 +149,9 @@ static void igc_ptp_systim_to_hwtstamp(struct igc_adapter *adapter,
 						systim & 0xFFFFFFFF);
 		break;
 	default:
-		break;
+		return -EINVAL;
 	}
+	return 0;
 }
 
 /**
@@ -372,7 +375,8 @@ static void igc_ptp_tx_hwtstamp(struct igc_adapter *adapter)
 
 	regval = rd32(IGC_TXSTMPL);
 	regval |= (u64)rd32(IGC_TXSTMPH) << 32;
-	igc_ptp_systim_to_hwtstamp(adapter, &shhwtstamps, regval);
+	if (igc_ptp_systim_to_hwtstamp(adapter, &shhwtstamps, regval))
+		return;
 
 	switch (adapter->link_speed) {
 	case SPEED_10: