gve: handle overflow when reporting TX consumed descriptors

When the tx tail is less than the head (in cases of wraparound), the TX
consumed descriptor statistic in DQ will be reported as
UINT32_MAX - head + tail, which is incorrect. Mask the difference of
head and tail according to the ring size when reporting the statistic.

Cc: stable@vger.kernel.org
Fixes: 2c9198356d56 ("gve: Add consumed counts to ethtool stats")
Signed-off-by: Joshua Washington <joshwash@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250402001037.2717315-1-hramamurthy@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/google/gve/gve_ethtool.c b/drivers/net/ethernet/google/gve/gve_ethtool.c
index 31a21ccf486348c4d1ba72e1b822993031220b13..4dea1fdce748cf4b30113452f58b9fa3aefa7297 100644 (file)
--- a/drivers/net/ethernet/google/gve/gve_ethtool.c
+++ b/drivers/net/ethernet/google/gve/gve_ethtool.c
@@ -392,7 +392,9 @@ gve_get_ethtool_stats(struct net_device *netdev,
                                 */
                                data[i++] = 0;
                                data[i++] = 0;
-                               data[i++] = tx->dqo_tx.tail - tx->dqo_tx.head;
+                               data[i++] =
+                                       (tx->dqo_tx.tail - tx->dqo_tx.head) &
+                                       tx->mask;
                        }
                        do {
                                start =