[PATCH net 3/4] gve: Use default min ring size when device option values are 0

[Harshitha Ramamurthy <hramamurthy@google.com>]

From: Pin-yen Lin <treapking@google.com>

On gvnic devices that support reporting minimum ring sizes, the device
option always includes the min_(rx|tx)_ring_size fields, and the values
will be 0 if they are not configured to be exposed. This makes the
driver allow unexpected small ring size configurations from the
userspace.

Use the default ring size in the driver if the min ring sizes from the
device option are 0.

This was discovered by drivers/net/ring_reconfig.py selftest.

Cc: stable@vger.kernel.org
Fixes: ed4fb326947d ("gve: add support to read ring size ranges from the device")
Reviewed-by: Joshua Washington <joshwash@google.com>
Reviewed-by: Jordan Rhee <jordanrhee@google.com>
Signed-off-by: Pin-yen Lin <treapking@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
---
 drivers/net/ethernet/google/gve/gve_adminq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/google/gve/gve_adminq.c b/drivers/net/ethernet/google/gve/gve_adminq.c
index b72cc0fa2ba2..57d898f6fa82 100644
--- a/drivers/net/ethernet/google/gve/gve_adminq.c
+++ b/drivers/net/ethernet/google/gve/gve_adminq.c
@@ -189,7 +189,9 @@ void gve_parse_device_option(struct gve_priv *priv,
 		*dev_op_modify_ring = (void *)(option + 1);
 
 		/* device has not provided min ring size */
-		if (option_length == GVE_DEVICE_OPTION_NO_MIN_RING_SIZE)
+		if (option_length == GVE_DEVICE_OPTION_NO_MIN_RING_SIZE ||
+		    be16_to_cpu((*dev_op_modify_ring)->min_rx_ring_size) == 0 ||
+		    be16_to_cpu((*dev_op_modify_ring)->min_tx_ring_size) == 0)
 			priv->default_min_ring_size = true;
 		break;
 	case GVE_DEV_OPT_ID_FLOW_STEERING:
-- 
2.54.0.rc0.605.g598a273b03-goog