[PATCH 4.19 013/191] ravb: Fix bit fields checking in ravb_hwtstamp_get()

[Greg Kroah-Hartman]

From: Andrew Gabbasov <andrew_gabbasov@xxxxxxxxxx>

[ Upstream commit 68b9f0865b1ef545da180c57d54b82c94cb464a4 ]

In the function ravb_hwtstamp_get() in ravb_main.c with the existing
values for RAVB_RXTSTAMP_TYPE_V2_L2_EVENT (0x2) and RAVB_RXTSTAMP_TYPE_ALL
(0x6)

if (priv->tstamp_rx_ctrl & RAVB_RXTSTAMP_TYPE_V2_L2_EVENT)
	config.rx_filter = HWTSTAMP_FILTER_PTP_V2_L2_EVENT;
else if (priv->tstamp_rx_ctrl & RAVB_RXTSTAMP_TYPE_ALL)
	config.rx_filter = HWTSTAMP_FILTER_ALL;

if the test on RAVB_RXTSTAMP_TYPE_ALL should be true,
it will never be reached.

This issue can be verified with 'hwtstamp_config' testing program
(tools/testing/selftests/net/hwtstamp_config.c). Setting filter type
to ALL and subsequent retrieving it gives incorrect value:

$ hwtstamp_config eth0 OFF ALL
flags = 0
tx_type = OFF
rx_filter = ALL
$ hwtstamp_config eth0
flags = 0
tx_type = OFF
rx_filter = PTP_V2_L2_EVENT

Correct this by converting if-else's to switch.

Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
Reported-by: Julia Lawall <julia.lawall@xxxxxxxx>
Signed-off-by: Andrew Gabbasov <andrew_gabbasov@xxxxxxxxxx>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxx>
Link: https://lore.kernel.org/r/20201026102130.29368-1-andrew_gabbasov@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/renesas/ravb_main.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -1732,12 +1732,16 @@ static int ravb_hwtstamp_get(struct net_
 	config.flags = 0;
 	config.tx_type = priv->tstamp_tx_ctrl ? HWTSTAMP_TX_ON :
 						HWTSTAMP_TX_OFF;
-	if (priv->tstamp_rx_ctrl & RAVB_RXTSTAMP_TYPE_V2_L2_EVENT)
+	switch (priv->tstamp_rx_ctrl & RAVB_RXTSTAMP_TYPE) {
+	case RAVB_RXTSTAMP_TYPE_V2_L2_EVENT:
 		config.rx_filter = HWTSTAMP_FILTER_PTP_V2_L2_EVENT;
-	else if (priv->tstamp_rx_ctrl & RAVB_RXTSTAMP_TYPE_ALL)
+		break;
+	case RAVB_RXTSTAMP_TYPE_ALL:
 		config.rx_filter = HWTSTAMP_FILTER_ALL;
-	else
+		break;
+	default:
 		config.rx_filter = HWTSTAMP_FILTER_NONE;
+	}
 
 	return copy_to_user(req->ifr_data, &config, sizeof(config)) ?
 		-EFAULT : 0;